/* =====================================================================
   sultanops — main stylesheet
   Colours, fonts, radii and spring easings come from tokens.css, which is
   generated from src/_data/brand.js. Nothing here hard-codes a brand value.
   Direction-aware: logical properties keep one rule set for Arabic and English.
   ===================================================================== */

@layer reset, base, layout, components, pages, utilities, responsive;

/* ---------- Reset ---------- */
@layer reset {
    *,
    *::before,
    *::after {
        box-sizing: border-box;
    }

    * {
        margin: 0;
    }

    ul,
    ol {
        padding: 0;
    }

    img,
    svg {
        display: block;
        max-width: 100%;
    }

    img {
        height: auto;
    }

    input,
    button {
        font: inherit;
        color: inherit;
    }

    button {
        cursor: pointer;
        background: none;
        border: 0;
    }

    [hidden] {
        display: none !important;
    }
}

/* ---------- Base ---------- */
@layer base {
    html {
        -webkit-text-size-adjust: 100%;
        text-size-adjust: 100%;
        scroll-padding-top: 88px;
    }

    body {
        min-height: 100vh;
        display: flex;
        flex-direction: column;
        background: var(--color-bg);
        color: var(--color-ink);
        font-family: var(--font-sans);
        font-size: 1.0625rem;
        line-height: 1.75;
        -webkit-font-smoothing: antialiased;
        text-rendering: optimizeLegibility;
    }

    :lang(en) body,
    body:lang(en) {
        line-height: 1.65;
    }

    h1,
    h2,
    h3,
    h4 {
        line-height: 1.3;
        font-weight: 600;
        text-wrap: balance;
    }

    /* Latin text gets slight tightening; Arabic is never letter-spaced (it breaks joining). */
    :lang(en) h1,
    :lang(en) h2 {
        letter-spacing: -0.015em;
    }

    p {
        text-wrap: pretty;
    }

    a {
        color: inherit;
        text-decoration: none;
    }

    ::selection {
        background: var(--color-accent-soft);
        color: var(--color-ink);
    }

    :focus-visible {
        outline: 2px solid var(--color-accent);
        outline-offset: 2px;
        border-radius: 4px;
    }

    code,
    kbd,
    pre,
    samp {
        font-family: var(--font-mono);
    }

    .icon {
        width: 1.15em;
        height: 1.15em;
        flex-shrink: 0;
    }

    [dir="rtl"] .flip-rtl,
    [dir="ltr"] .flip-ltr {
        transform: scaleX(-1);
    }
}

/* ---------- Layout ---------- */
@layer layout {
    .container {
        width: 100%;
        max-width: 1120px;
        margin-inline: auto;
        padding-inline: clamp(16px, 4vw, 32px);
    }

    .site-main {
        flex: 1 0 auto;
    }

    .section {
        padding-block: clamp(2.5rem, 6vw, 4.5rem);
    }

    .section + .section {
        padding-top: 0;
    }

    .section-head {
        display: flex;
        align-items: end;
        justify-content: space-between;
        gap: 1rem;
        margin-bottom: 1.5rem;
    }

    .section-title {
        font-size: 1.4rem;
    }

    .section-text {
        margin-top: 0.35rem;
        color: var(--color-muted);
        font-size: 0.98rem;
    }

    /* Header */
    .site-header {
        position: sticky;
        top: 0;
        z-index: 50;
        border-bottom: 1px solid var(--color-line);
        transition: transform var(--dur-soft) var(--ease-soft);
    }

    /* The blur lives on a pseudo-element: a backdrop-filter on the header itself would make it
       the containing block for the fixed mobile menu and collapse that panel to the header's size. */
    .site-header::before {
        content: '';
        position: absolute;
        inset: 0;
        z-index: -1;
        background: color-mix(in srgb, var(--color-bg) 88%, transparent);
        backdrop-filter: saturate(1.4) blur(12px);
        -webkit-backdrop-filter: saturate(1.4) blur(12px);
    }

    .site-header.is-hidden {
        transform: translateY(-100%);
    }

    .header-bar {
        display: flex;
        align-items: center;
        gap: 1.5rem;
        height: 64px;
    }

    .brand {
        display: inline-flex;
        align-items: center;
        gap: 0.6rem;
        color: var(--color-ink);
    }

    .brand-word {
        font-family: var(--font-mono);
        font-size: 1.05rem;
        font-weight: 600;
        letter-spacing: -0.01em;
        direction: ltr;
    }

    .logo-mark {
        width: 28px;
        height: 28px;
    }

    .site-nav {
        margin-inline-start: auto;
    }

    .nav-links {
        position: relative;
        display: flex;
        align-items: center;
        gap: 0.25rem;
        list-style: none;
    }

    .nav-link {
        position: relative;
        z-index: 1;
        display: block;
        padding: 0.35rem 0.85rem;
        border-radius: var(--radius-sm);
        color: var(--color-muted);
        font-size: 0.95rem;
        font-weight: 600;
        transition: color 150ms ease;
    }

    .nav-link:hover,
    .nav-link[aria-current="page"] {
        color: var(--color-ink);
    }

    /* Without JavaScript the current link carries its own background. */
    .nav-links:not(.has-indicator) .nav-link[aria-current="page"] {
        background: var(--color-sunken);
    }

    /* The indicator's two edges move on different springs, so it stretches and settles. */
    .nav-indicator {
        position: absolute;
        top: 0;
        bottom: 0;
        left: var(--indicator-left, 0);
        right: var(--indicator-right, 100%);
        border-radius: var(--radius-sm);
        background: var(--color-sunken);
        opacity: 0;
        pointer-events: none;
    }

    .nav-links.has-indicator .nav-indicator {
        opacity: 1;
    }

    .nav-indicator.is-ready.moves-right {
        transition:
            right var(--dur-snappy) var(--ease-snappy),
            left var(--dur-soft) var(--ease-soft);
    }

    .nav-indicator.is-ready.moves-left {
        transition:
            left var(--dur-snappy) var(--ease-snappy),
            right var(--dur-soft) var(--ease-soft);
    }

    .header-actions {
        display: flex;
        align-items: center;
        gap: 0.4rem;
    }

    .reading-progress {
        position: fixed;
        inset-inline: 0;
        top: 0;
        z-index: 60;
        height: 2px;
        background: var(--color-accent);
        transform: scaleX(var(--progress, 0));
        transform-origin: left;
        display: none;
    }

    [dir="rtl"] .reading-progress {
        transform-origin: right;
    }

    .page-post .reading-progress {
        display: block;
    }

    /* Footer */
    .site-footer {
        margin-top: clamp(4rem, 8vw, 6rem);
        border-top: 1px solid var(--color-line);
        background: var(--color-sunken);
        padding-block: 3rem 1.5rem;
        font-size: 0.92rem;
    }

    .footer-grid {
        display: grid;
        grid-template-columns: 2fr repeat(3, 1fr);
        gap: 2rem;
    }

    .footer-brand p {
        margin-top: 0.85rem;
        max-width: 22rem;
        color: var(--color-muted);
    }

    .footer-col h2 {
        margin-bottom: 0.75rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        font-weight: 400;
        letter-spacing: 0.06em;
        text-transform: uppercase;
    }

    .footer-col ul {
        display: grid;
        gap: 0.45rem;
        list-style: none;
    }

    .footer-col a {
        display: inline-flex;
        align-items: center;
        gap: 0.45rem;
        color: var(--color-muted);
        transition: color 150ms ease;
    }

    .footer-col a:hover {
        color: var(--color-ink);
    }

    .footer-col .icon {
        width: 16px;
        height: 16px;
    }

    .footer-bottom {
        display: flex;
        flex-wrap: wrap;
        justify-content: space-between;
        gap: 0.5rem 1.5rem;
        margin-top: 2.5rem;
        padding-top: 1.25rem;
        border-top: 1px solid var(--color-line);
        color: var(--color-faint);
        font-size: 0.82rem;
    }
}

/* ---------- Components ---------- */
@layer components {
    .eyebrow {
        display: inline-flex;
        align-items: center;
        gap: 0.5rem;
        color: var(--color-muted);
        font-family: var(--font-mono);
        font-size: 0.78rem;
        font-weight: 400;
        letter-spacing: 0.04em;
    }

    .eyebrow::before {
        content: '';
        width: 6px;
        height: 6px;
        border-radius: 1px;
        background: var(--color-accent);
    }

    .icon-btn {
        display: inline-grid;
        place-items: center;
        width: 38px;
        height: 38px;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        background: var(--color-surface);
        color: var(--color-muted);
        transition:
            background-color 150ms ease,
            color 150ms ease,
            border-color 150ms ease;
    }

    .icon-btn:hover {
        border-color: var(--color-line-strong);
        color: var(--color-ink);
    }

    .icon-btn .icon {
        width: 18px;
        height: 18px;
        grid-area: 1 / 1;
    }

    .lang-code {
        font-family: var(--font-sans);
        font-size: 0.85rem;
        font-weight: 600;
        line-height: 1;
    }

    /* Theme button: the moon shows in light mode, the sun in dark mode; they cross-fade. */
    .theme-btn .icon {
        transition:
            opacity 200ms ease,
            transform var(--dur-snappy) var(--ease-snappy);
    }

    .theme-btn .icon-sun {
        opacity: 0;
        transform: rotate(-90deg) scale(0.6);
    }

    @media (prefers-color-scheme: dark) {
        :root:not([data-theme="light"]) .theme-btn .icon-sun {
            opacity: 1;
            transform: none;
        }

        :root:not([data-theme="light"]) .theme-btn .icon-moon {
            opacity: 0;
            transform: rotate(90deg) scale(0.6);
        }
    }

    :root[data-theme="dark"] .theme-btn .icon-sun {
        opacity: 1;
        transform: none;
    }

    :root[data-theme="dark"] .theme-btn .icon-moon {
        opacity: 0;
        transform: rotate(90deg) scale(0.6);
    }

    .menu-btn {
        display: none;
    }

    .menu-btn .icon-close,
    .menu-btn[aria-expanded="true"] .icon-menu {
        opacity: 0;
    }

    .menu-btn[aria-expanded="true"] .icon-close {
        opacity: 1;
    }

    .btn {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: 0.5rem;
        min-height: 44px;
        padding: 0.55rem 1.15rem;
        border: 1px solid var(--color-line-strong);
        border-radius: var(--radius-md);
        background: transparent;
        color: var(--color-ink);
        font-size: 0.95rem;
        font-weight: 600;
        line-height: 1.3;
        text-decoration: none;
        transition:
            background-color 150ms ease,
            border-color 150ms ease,
            transform var(--dur-snappy) var(--ease-snappy);
    }

    .btn:hover {
        background: var(--color-sunken);
    }

    .btn:active {
        transform: scale(0.98);
    }

    .btn .icon {
        width: 18px;
        height: 18px;
        transition: transform var(--dur-snappy) var(--ease-snappy);
    }

    .btn-primary {
        border-color: var(--color-ink);
        background: var(--color-ink);
        color: var(--color-bg);
    }

    .btn-primary:hover {
        background: color-mix(in srgb, var(--color-ink) 86%, var(--color-bg));
    }

    .btn-primary:hover .icon {
        transform: translateX(3px);
    }

    [dir="rtl"] .btn-primary:hover .icon {
        transform: scaleX(-1) translateX(3px);
    }

    .text-link {
        display: inline-flex;
        align-items: center;
        gap: 0.35rem;
        color: var(--color-accent);
        font-size: 0.95rem;
        font-weight: 600;
    }

    .text-link .icon {
        width: 16px;
        height: 16px;
        transition: transform var(--dur-snappy) var(--ease-snappy);
    }

    .text-link:hover .icon:not(.flip-rtl) {
        transform: translateX(2px);
    }

    [dir="ltr"] .text-link:hover .flip-rtl {
        transform: translateX(3px);
    }

    [dir="rtl"] .text-link:hover .flip-rtl {
        transform: scaleX(-1) translateX(3px);
    }

    /* Article list rows. The row background moves first; title colour and arrow follow
       a beat later, so the container and its text never animate in lockstep. */
    .post-list {
        list-style: none;
        border-top: 1px solid var(--color-line);
    }

    .post-row {
        position: relative;
        isolation: isolate;
        display: grid;
        grid-template-columns: 8.5rem minmax(0, 1fr) 1.5rem;
        gap: 0.5rem 1.5rem;
        padding-block: 1.4rem;
        border-bottom: 1px solid var(--color-line);
    }

    .post-row::before {
        content: '';
        position: absolute;
        inset-block: -1px;
        inset-inline: -1rem;
        z-index: -1;
        border-radius: var(--radius-md);
        background: var(--color-surface);
        box-shadow: 0 0 0 1px var(--color-line);
        opacity: 0;
        transform: scale(0.985);
        transition:
            opacity 160ms ease,
            transform var(--dur-soft) var(--ease-soft);
    }

    .post-row:hover::before,
    .post-row:focus-within::before {
        opacity: 1;
        transform: none;
    }

    .post-row-date {
        padding-top: 0.2rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.8rem;
        white-space: nowrap;
    }

    .post-row-title {
        font-size: 1.18rem;
        line-height: 1.45;
    }

    .post-row-title a {
        transition: color 150ms ease 60ms;
    }

    .post-row-title a::after {
        content: '';
        position: absolute;
        inset: 0;
    }

    .post-row:hover .post-row-title a {
        color: var(--color-accent);
    }

    .post-row-text {
        margin-top: 0.35rem;
        max-width: 62ch;
        color: var(--color-muted);
        font-size: 0.97rem;
        line-height: 1.7;
        display: -webkit-box;
        -webkit-line-clamp: 2;
        -webkit-box-orient: vertical;
        overflow: hidden;
    }

    .post-row-meta {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 0.35rem 0.9rem;
        margin-top: 0.7rem;
        color: var(--color-faint);
        font-size: 0.82rem;
    }

    .topic-label {
        color: var(--color-muted);
        font-weight: 600;
    }

    .topic-label + .topic-label::before {
        content: '·';
        margin-inline-end: 0.9rem;
        color: var(--color-faint);
    }

    .post-row-time {
        display: inline-flex;
        align-items: center;
        gap: 0.3rem;
    }

    .post-row-time .icon {
        width: 14px;
        height: 14px;
    }

    .post-row-arrow {
        align-self: center;
        color: var(--color-faint);
        opacity: 0;
        transform: translateX(-6px);
        transition:
            opacity 150ms ease 80ms,
            transform var(--dur-snappy) var(--ease-snappy) 80ms,
            color 150ms ease;
    }

    [dir="rtl"] .post-row-arrow {
        transform: scaleX(-1) translateX(-6px);
    }

    .post-row:hover .post-row-arrow {
        opacity: 1;
        transform: none;
        color: var(--color-accent);
    }

    [dir="rtl"] .post-row:hover .post-row-arrow {
        transform: scaleX(-1);
    }

    .post-row-arrow .icon {
        width: 20px;
        height: 20px;
    }

    /* Chips */
    .chips ul {
        display: flex;
        flex-wrap: wrap;
        gap: 0.5rem;
        list-style: none;
    }

    .chip {
        display: inline-flex;
        align-items: center;
        gap: 0.4rem;
        min-height: 34px;
        padding: 0.25rem 0.8rem;
        border: 1px solid var(--color-line);
        border-radius: 999px;
        background: var(--color-surface);
        color: var(--color-ink);
        font-size: 0.88rem;
        font-weight: 600;
        transition:
            border-color 150ms ease,
            background-color 150ms ease;
    }

    .chip:hover {
        border-color: var(--color-line-strong);
        background: var(--color-sunken);
    }

    .chip .icon {
        width: 15px;
        height: 15px;
        color: var(--color-muted);
    }

    .chip-count {
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.72rem;
    }

    .chip[aria-current="page"] {
        border-color: var(--color-ink);
        background: var(--color-ink);
        color: var(--color-bg);
    }

    .chip[aria-current="page"] .icon,
    .chip[aria-current="page"] .chip-count {
        color: inherit;
    }

    /* Topic tiles */
    .topic-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(min(250px, 100%), 1fr));
        gap: 1rem;
        list-style: none;
    }

    .topic-card {
        position: relative;
        display: flex;
        flex-direction: column;
        gap: 0.35rem;
        padding: 1.25rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-lg);
        background: var(--color-surface);
        transition:
            border-color 150ms ease,
            transform var(--dur-soft) var(--ease-soft);
    }

    .topic-card:hover {
        border-color: var(--color-line-strong);
        transform: translateY(-2px);
    }

    .topic-icon {
        display: grid;
        place-items: center;
        width: 38px;
        height: 38px;
        margin-bottom: 0.6rem;
        border-radius: var(--radius-md);
        background: var(--color-accent-soft);
        color: var(--color-accent);
        transition:
            background-color 200ms ease 60ms,
            color 200ms ease 60ms;
    }

    .topic-icon .icon {
        width: 20px;
        height: 20px;
    }

    .topic-card:hover .topic-icon {
        background: var(--color-accent);
        color: var(--color-accent-ink);
    }

    .topic-name {
        font-size: 1.05rem;
    }

    .topic-name a::after {
        content: '';
        position: absolute;
        inset: 0;
        border-radius: inherit;
    }

    .topic-text {
        color: var(--color-muted);
        font-size: 0.92rem;
        line-height: 1.65;
    }

    .topic-count {
        margin-top: auto;
        padding-top: 0.6rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
    }

    /* Author */
    .author-card {
        display: flex;
        gap: 1.25rem;
        align-items: flex-start;
        padding: clamp(1.25rem, 3vw, 2rem);
        border: 1px solid var(--color-line);
        border-radius: var(--radius-lg);
        background: var(--color-surface);
    }

    .author-avatar {
        display: grid;
        place-items: center;
        flex-shrink: 0;
        width: 56px;
        height: 56px;
        border-radius: 50%;
        background: var(--color-ink);
        color: var(--color-bg);
        font-size: 1.4rem;
        font-weight: 700;
    }

    .author-text {
        margin-block: 0.5rem 0.85rem;
        max-width: 60ch;
        font-size: 1.05rem;
    }

    /* Terminal (hero, 404) — always dark */
    .terminal {
        overflow: hidden;
        border: 1px solid var(--code-line);
        border-radius: var(--radius-lg);
        background: var(--code-bg);
        color: var(--code-ink);
        box-shadow: 0 24px 48px -28px rgb(0 0 0 / 0.45);
        text-align: left;
    }

    .terminal-bar {
        display: flex;
        align-items: center;
        gap: 0.75rem;
        height: 38px;
        padding-inline: 0.9rem;
        border-bottom: 1px solid var(--code-line);
        background: var(--code-bar);
    }

    .terminal-dots {
        display: flex;
        gap: 6px;
    }

    .terminal-dots i {
        width: 10px;
        height: 10px;
        border-radius: 50%;
        background: var(--code-line);
    }

    .terminal-title {
        flex: 1;
        margin-inline-end: 42px;
        color: var(--code-muted);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        text-align: center;
    }

    .terminal-body {
        height: calc(11 * 1.7em + 2.25rem);
        margin: 0;
        padding: 1rem 1.15rem 1.25rem;
        overflow: hidden;
        font-size: 0.82rem;
        line-height: 1.7;
        white-space: pre;
    }

    .terminal-compact .terminal-body {
        height: auto;
        white-space: pre-wrap;
        word-break: break-all;
    }

    .t-prompt {
        color: var(--code-accent);
        font-weight: 600;
    }

    .t-out {
        color: var(--code-muted);
    }

    .t-ok {
        color: var(--code-accent);
    }

    .t-error {
        color: var(--code-danger);
    }

    .t-path {
        color: var(--code-ink);
    }

    .t-caret {
        display: inline-block;
        width: 0.55em;
        height: 1.15em;
        vertical-align: -0.2em;
        background: var(--code-accent);
        animation: caret-blink 1.1s steps(1) infinite;
    }

    /* When main.js drives the terminal, seek(t) decides the caret state. */
    .terminal.is-driven .t-caret {
        animation: none;
    }

    .t-caret.is-off {
        opacity: 0;
    }

    @keyframes caret-blink {
        50% {
            opacity: 0;
        }
    }

    /* Search */
    .search-field {
        position: relative;
        max-width: 34rem;
    }

    .search-field > .icon {
        position: absolute;
        top: 50%;
        inset-inline-start: 0.95rem;
        width: 18px;
        height: 18px;
        color: var(--color-faint);
        transform: translateY(-50%);
        pointer-events: none;
    }

    .search-input {
        width: 100%;
        height: 48px;
        padding-inline: 2.75rem 1rem;
        border: 1px solid var(--color-line-strong);
        border-radius: var(--radius-md);
        background: var(--color-surface);
        font-size: 1rem;
        transition:
            border-color 150ms ease,
            box-shadow 150ms ease;
    }

    .search-input::placeholder {
        color: var(--color-faint);
    }

    .search-input:focus {
        outline: none;
        border-color: var(--color-accent);
        box-shadow: 0 0 0 3px var(--color-accent-soft);
    }

    .empty-state {
        padding: 3rem 1rem;
        color: var(--color-muted);
        text-align: center;
    }

    .back-to-top {
        position: fixed;
        bottom: 24px;
        inset-inline-end: 24px;
        z-index: 40;
        opacity: 0;
        transform: translateY(8px);
        pointer-events: none;
        transition:
            opacity 200ms ease,
            transform var(--dur-soft) var(--ease-soft);
    }

    .back-to-top.is-visible {
        opacity: 1;
        transform: none;
        pointer-events: auto;
    }

    .skip-link {
        position: absolute;
        top: 0.75rem;
        inset-inline-start: 0.75rem;
        z-index: 100;
        padding: 0.5rem 1rem;
        border-radius: var(--radius-sm);
        background: var(--color-ink);
        color: var(--color-bg);
        transform: translateY(-200%);
    }

    .skip-link:focus {
        transform: none;
    }
}

/* ---------- Pages ---------- */
@layer pages {
    /* Home */
    .hero {
        position: relative;
        isolation: isolate;
        padding-block: clamp(3rem, 8vw, 6rem) clamp(2.5rem, 6vw, 4.5rem);
        overflow: hidden;
    }

    /* A faint dot grid — texture without decoration. */
    .hero::before {
        content: '';
        position: absolute;
        inset: 0;
        z-index: -1;
        background-image: radial-gradient(var(--color-line-strong) 1px, transparent 1.2px);
        background-size: 22px 22px;
        -webkit-mask-image: linear-gradient(to bottom, #000 0%, transparent 85%);
        mask-image: linear-gradient(to bottom, #000 0%, transparent 85%);
        opacity: 0.6;
    }

    .hero-grid {
        display: grid;
        grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
        gap: clamp(2rem, 5vw, 4rem);
        align-items: center;
    }

    .hero-title {
        margin-top: 1rem;
        font-size: clamp(2rem, 4.4vw, 3.3rem);
        font-weight: 700;
        line-height: 1.25;
    }

    :lang(en) .hero-title {
        line-height: 1.12;
    }

    .hero-text {
        margin-top: 1.25rem;
        max-width: 36em;
        color: var(--color-muted);
        font-size: 1.12rem;
        line-height: 1.8;
    }

    .hero-actions {
        display: flex;
        flex-wrap: wrap;
        gap: 0.75rem;
        margin-top: 2rem;
    }

    /* Page header (blog, tags, about) */
    .page-head {
        padding-block: clamp(2.5rem, 6vw, 4rem) 2rem;
        max-width: 46rem;
    }

    .page-title {
        margin-top: 0.75rem;
        font-size: clamp(1.9rem, 3.6vw, 2.6rem);
        font-weight: 700;
    }

    .page-lead {
        margin-top: 0.85rem;
        color: var(--color-muted);
        font-size: 1.1rem;
    }

    .topic-head .topic-icon {
        margin-bottom: 1rem;
    }

    .topic-icon-lg {
        width: 48px;
        height: 48px;
    }

    .topic-icon-lg .icon {
        width: 24px;
        height: 24px;
    }

    .page-prose {
        max-width: 46rem;
    }

    /* Blog */
    .blog-tools {
        display: grid;
        gap: 1rem;
        margin-bottom: 1rem;
    }

    .year-label {
        margin-block: 2.5rem 0.75rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.85rem;
        font-weight: 400;
    }

    .chips-footer {
        margin-top: 3rem;
    }

    .chips-title {
        margin-bottom: 0.75rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        letter-spacing: 0.06em;
        text-transform: uppercase;
    }

    /* Post */
    .post-head {
        padding-block: clamp(2rem, 5vw, 3.5rem) 2rem;
    }

    .post-head > * {
        max-width: 46rem;
    }

    .breadcrumb {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 0.5rem;
        color: var(--color-muted);
        font-size: 0.88rem;
    }

    .breadcrumb a {
        padding-block: 0.25rem;
    }

    .breadcrumb a:hover {
        color: var(--color-accent);
    }

    .breadcrumb-sep {
        color: var(--color-faint);
    }

    .post-title {
        margin-top: 1rem;
        font-size: clamp(1.85rem, 4vw, 2.7rem);
        font-weight: 700;
        line-height: 1.3;
    }

    :lang(en) .post-title {
        line-height: 1.18;
    }

    .post-lead {
        margin-top: 1rem;
        color: var(--color-muted);
        font-size: 1.12rem;
        line-height: 1.75;
    }

    .post-meta {
        display: flex;
        flex-wrap: wrap;
        gap: 0.5rem 1.4rem;
        margin-top: 1.5rem;
        padding-top: 1.25rem;
        border-top: 1px solid var(--color-line);
        color: var(--color-muted);
        font-size: 0.88rem;
        list-style: none;
    }

    .post-meta li {
        display: inline-flex;
        align-items: center;
        gap: 0.4rem;
    }

    .post-meta .icon {
        width: 16px;
        height: 16px;
        color: var(--color-faint);
    }

    .post-layout {
        display: grid;
        grid-template-columns: minmax(0, 46rem);
    }

    .post-main {
        min-width: 0;
    }

    .post-aside {
        display: none;
    }

    /* Table of contents */
    .toc-title {
        display: flex;
        align-items: center;
        gap: 0.5rem;
        margin-bottom: 0.75rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        letter-spacing: 0.06em;
        text-transform: uppercase;
    }

    .toc-title .icon {
        width: 15px;
        height: 15px;
    }

    .toc-count {
        margin-inline-start: auto;
        color: var(--color-accent);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        font-weight: 600;
        letter-spacing: 0;
    }

    .toc-list {
        list-style: none;
        border-inline-start: 1px solid var(--color-line);
        counter-reset: toc;
    }

    .toc-list li {
        counter-increment: toc;
    }

    .toc-list a {
        position: relative;
        display: flex;
        gap: 0.6rem;
        padding-block: 0.32rem;
        padding-inline-start: 0.9rem;
        color: var(--color-muted);
        font-size: 0.86rem;
        line-height: 1.5;
        transition: color 150ms ease;
    }

    .toc-list.is-numbered a::before {
        content: counter(toc, decimal-leading-zero);
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        line-height: 1.95;
    }

    .toc-list a::after {
        content: '';
        position: absolute;
        inset-block: 0.3rem;
        inset-inline-start: -1px;
        width: 2px;
        border-radius: 2px;
        background: var(--color-accent);
        transform: scaleY(0);
        transition: transform var(--dur-snappy) var(--ease-snappy);
    }

    /* A tick takes the place of the number for what's been read. */
    :root {
        --mask-check: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='black' stroke-width='3' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M5 12.5l4.5 4.5L19 7.5'/%3E%3C/svg%3E");
    }

    .toc-list a.is-read::before {
        content: '';
        flex-shrink: 0;
        width: 0.95rem;
        height: 1.29rem;
        background: var(--color-accent);
        -webkit-mask: var(--mask-check) center / contain no-repeat;
        mask: var(--mask-check) center / contain no-repeat;
    }

    .toc-list a:hover,
    .toc-list a.is-active {
        color: var(--color-ink);
    }

    .toc-list a.is-active::after {
        transform: scaleY(1);
    }

    .toc-inline {
        margin-bottom: 2rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        background: var(--color-surface);
    }

    .toc-inline summary {
        display: flex;
        align-items: center;
        gap: 0.5rem;
        padding: 0.8rem 1rem;
        color: var(--color-muted);
        font-size: 0.92rem;
        font-weight: 600;
        cursor: pointer;
        list-style: none;
    }

    .toc-inline summary::-webkit-details-marker {
        display: none;
    }

    .toc-inline summary .icon {
        width: 16px;
        height: 16px;
    }

    .toc-inline .toc-list {
        margin: 0 1rem 1rem;
    }

    @media (min-width: 1100px) {
        .post-layout.has-toc {
            grid-template-columns: minmax(0, 46rem) 15rem;
            justify-content: space-between;
            gap: 4rem;
        }

        .post-aside {
            display: block;
            order: 2;
        }

        .toc {
            position: sticky;
            top: 96px;
            max-height: calc(100vh - 120px);
            overflow-y: auto;
        }

        .toc-inline {
            display: none;
        }
    }

    .post-foot {
        margin-top: 3.5rem;
        padding-top: 2rem;
        border-top: 1px solid var(--color-line);
    }

    .post-nav {
        display: grid;
        grid-template-columns: 1fr 1fr;
        gap: 1rem;
        margin-top: 2rem;
    }

    .post-nav-link {
        display: flex;
        flex-direction: column;
        gap: 0.35rem;
        padding: 1rem 1.15rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        transition:
            border-color 150ms ease,
            background-color 150ms ease;
    }

    .post-nav-link:hover {
        border-color: var(--color-line-strong);
        background: var(--color-surface);
    }

    .post-nav-link.is-newer {
        grid-column: 2;
        align-items: flex-end;
        text-align: end;
    }

    .post-nav-label {
        display: inline-flex;
        align-items: center;
        gap: 0.4rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
    }

    .post-nav-label .icon {
        width: 14px;
        height: 14px;
    }

    .post-nav-title {
        font-weight: 600;
        font-size: 0.98rem;
        line-height: 1.5;
    }

    /* 404 */
    .not-found {
        max-width: 40rem;
        padding-block: clamp(3rem, 8vw, 5rem);
        text-align: center;
    }

    .not-found .terminal {
        margin-bottom: 2.5rem;
    }

    .not-found-en {
        font-size: 0.98rem;
    }

    .not-found .hero-actions {
        justify-content: center;
    }

    /* ---------- Prose: article body ---------- */
    .prose {
        font-size: 1.0625rem;
        line-height: 1.9;
        counter-reset: section;
        overflow-wrap: break-word;
    }

    :lang(en) .prose {
        line-height: 1.75;
    }

    .prose > * + * {
        margin-top: 1.15em;
    }

    .prose h2 {
        margin-top: 2.4em;
        font-size: 1.45rem;
        line-height: 1.4;
        scroll-margin-top: 88px;
    }

    .prose h2:first-child {
        margin-top: 0;
    }

    .prose.is-numbered h2 {
        counter-increment: section;
    }

    .prose.is-numbered h2::before {
        content: counter(section, decimal-leading-zero);
        display: block;
        margin-bottom: 0.2rem;
        color: var(--color-accent);
        font-family: var(--font-mono);
        font-size: 0.8rem;
        font-weight: 400;
    }

    .prose h3 {
        margin-top: 2em;
        font-size: 1.15rem;
        scroll-margin-top: 88px;
    }

    .prose h2 + *,
    .prose h3 + * {
        margin-top: 0.75em;
    }

    .heading-anchor {
        margin-inline-start: 0.4em;
        color: var(--color-faint);
        font-weight: 400;
        opacity: 0;
        transition: opacity 150ms ease;
    }

    .prose :is(h2, h3):hover .heading-anchor,
    .heading-anchor:focus-visible {
        opacity: 1;
    }

    /* Nothing reveals these on a touch screen, so they'd be invisible things to tap by accident. */
    @media (hover: none) {
        .heading-anchor {
            display: none;
        }
    }

    .prose a:not(.btn, .heading-anchor) {
        color: var(--color-accent);
        text-decoration: underline;
        text-decoration-thickness: 1px;
        text-underline-offset: 0.25em;
    }

    .prose a:not(.btn, .heading-anchor):hover {
        text-decoration-thickness: 2px;
    }

    .prose strong {
        font-weight: 600;
    }

    .prose ul {
        padding-inline-start: 1.3rem;
    }

    .prose ul > li::marker {
        color: var(--color-faint);
    }

    .prose li + li {
        margin-top: 0.4em;
    }

    /* Numbered lists are steps: a mono counter in a small square. */
    .prose ol {
        list-style: none;
        counter-reset: step;
    }

    .prose ol > li {
        position: relative;
        min-height: 1.9rem;
        padding-inline-start: 2.75rem;
        counter-increment: step;
    }

    .prose ol > li + li {
        margin-top: 0.9em;
    }

    .prose ol > li::before {
        content: counter(step, decimal-leading-zero);
        position: absolute;
        top: 0.2em;
        inset-inline-start: 0;
        display: grid;
        place-items: center;
        width: 1.9rem;
        height: 1.9rem;
        border: 1px solid var(--color-line-strong);
        border-radius: 7px;
        background: var(--color-surface);
        color: var(--color-ink);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        font-weight: 400;
        line-height: 1;
    }

    .prose img {
        margin-block: 1.75em;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
    }

    .prose :not(pre) > code {
        padding: 0.1em 0.38em;
        border: 1px solid var(--color-line);
        border-radius: 5px;
        background: var(--color-sunken);
        font-size: 0.86em;
        direction: ltr;
        unicode-bidi: isolate;
        /* Long URLs and paths wrap instead of widening the page on phones. */
        overflow-wrap: anywhere;
    }

    .prose blockquote {
        padding-inline-start: 1.1rem;
        border-inline-start: 3px solid var(--color-accent);
        color: var(--color-muted);
    }

    .prose hr {
        margin-block: 2.5em;
        border: 0;
        border-top: 1px solid var(--color-line);
    }

    .prose table {
        display: block;
        overflow-x: auto;
        border-collapse: collapse;
        font-size: 0.95rem;
    }

    .prose th,
    .prose td {
        padding: 0.55rem 0.75rem;
        border-bottom: 1px solid var(--color-line);
        text-align: start;
    }

    .prose th {
        color: var(--color-muted);
        font-weight: 600;
    }

    /* Callouts */
    .callout {
        padding: 1rem 1.15rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        background: var(--color-sunken);
        font-size: 0.98rem;
        line-height: 1.8;
    }

    .callout > * + * {
        margin-top: 0.4em;
    }

    .callout-title {
        display: flex;
        align-items: center;
        gap: 0.5rem;
        font-weight: 600;
    }

    .callout-title .icon {
        width: 18px;
        height: 18px;
        color: var(--color-muted);
    }

    .callout-tip {
        border-color: color-mix(in srgb, var(--color-accent) 28%, transparent);
        background: var(--color-accent-soft);
    }

    .callout-tip .callout-title .icon {
        color: var(--color-accent);
    }

    .callout-security {
        border-color: color-mix(in srgb, var(--color-warn) 30%, transparent);
        background: var(--color-warn-soft);
    }

    .callout-security .callout-title .icon {
        color: var(--color-warn);
    }

    .callout-warning {
        border-color: color-mix(in srgb, var(--color-danger) 30%, transparent);
        background: var(--color-danger-soft);
    }

    .callout-warning .callout-title .icon {
        color: var(--color-danger);
    }

    /* Self-test questions: one box. main.js shows one question at a time; without it they're all listed. */
    .quiz-deck {
        padding: 1.1rem 1.15rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        background: var(--color-surface);
        font-size: 1rem;
        line-height: 1.8;
        scroll-margin-top: 88px;
    }

    .quiz + .quiz {
        margin-top: 1.25rem;
        padding-top: 1.25rem;
        border-top: 1px solid var(--color-line);
    }

    .quiz-deck.is-stepped .quiz + .quiz {
        margin-top: 0;
        padding-top: 0;
        border-top: 0;
    }

    .quiz:focus {
        outline: none;
    }

    .quiz > * + * {
        margin-top: 0.75em;
    }

    .quiz-number {
        color: var(--color-muted);
        font-size: 0.82rem;
        font-weight: 600;
    }

    .prose .quiz-options {
        display: grid;
        gap: 0.5rem;
        padding: 0;
        list-style: none;
    }

    .prose .quiz-options > li {
        margin: 0;
    }

    .quiz-option {
        display: flex;
        align-items: flex-start;
        gap: 0.7rem;
        width: 100%;
        padding: 0.6rem 0.75rem;
        border: 1px solid var(--color-line-strong);
        border-radius: var(--radius-md);
        color: inherit;
        font: inherit;
        line-height: 1.7;
        text-align: start;
        cursor: pointer;
        transition: border-color var(--dur-snappy) var(--ease-snappy), background-color var(--dur-snappy) var(--ease-snappy);
    }

    .quiz-option:hover:not(:disabled, [aria-disabled="true"]) {
        border-color: var(--color-accent);
    }

    .quiz-option:disabled,
    .quiz-option[aria-disabled="true"] {
        color: inherit;
        cursor: default;
    }

    .quiz-option[aria-pressed="true"],
    .quiz-option.is-correct {
        border-color: var(--color-accent);
        background: var(--color-accent-soft);
    }

    .quiz-option.is-wrong {
        border-color: var(--color-danger);
        background: var(--color-danger-soft);
    }

    /* A mark beside the colour, so the result doesn't rely on colour alone. */
    .quiz-option.is-correct::after,
    .quiz-option.is-wrong::after {
        margin-inline-start: auto;
        padding-inline-start: 0.5rem;
        font-weight: 700;
    }

    .quiz-option.is-correct::after {
        content: "\2713";
        color: var(--color-accent);
    }

    .quiz-option.is-wrong::after {
        content: "\2715";
        color: var(--color-danger);
    }

    .quiz-letter {
        display: grid;
        flex: none;
        place-items: center;
        width: 1.7rem;
        height: 1.7rem;
        border-radius: 50%;
        background: var(--color-sunken);
        font-family: var(--font-mono);
        font-size: 0.78rem;
        font-weight: 600;
    }

    .quiz-option.is-correct .quiz-letter {
        background: var(--color-accent);
        color: var(--color-bg);
    }

    .quiz-option.is-wrong .quiz-letter {
        background: var(--color-danger);
        color: var(--color-bg);
    }

    .quiz > .quiz-result:empty {
        margin: 0;
    }

    .quiz-result {
        font-weight: 600;
    }

    .quiz-result.is-right {
        color: var(--color-accent);
    }

    .quiz-result.is-wrong {
        color: var(--color-danger);
    }

    .quiz-answer > summary {
        color: var(--color-accent);
        font-size: 0.95rem;
        font-weight: 600;
        cursor: pointer;
    }

    /* With the steps running, answering is what opens the explanation. */
    .quiz-deck.is-stepped .quiz-answer > summary {
        display: none;
    }

    .quiz-answer > * + * {
        margin-top: 0.6em;
    }

    .quiz-nav {
        display: flex;
        flex-wrap: wrap;
        justify-content: space-between;
        gap: 0.6rem;
        margin-top: 1.1rem;
        padding-top: 1rem;
        border-top: 1px solid var(--color-line);
    }

    .quiz-nav .btn-primary {
        margin-inline-start: auto;
    }

    .quiz-nav .btn:disabled {
        opacity: 0.45;
        cursor: not-allowed;
    }

    .quiz-summary {
        display: grid;
        justify-items: center;
        gap: 1rem;
        padding-block: 1.5rem;
        font-size: 1.15rem;
        font-weight: 600;
        text-align: center;
    }

    .quiz-deck.is-waiting > .quiz {
        display: none;
    }

    .quiz-start {
        display: grid;
        justify-items: center;
        gap: 1rem;
        padding-block: 1.5rem;
        text-align: center;
    }

    .quiz-start-title {
        font-size: 1.15rem;
        font-weight: 600;
    }

    .quiz-start-sizes {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 0.6rem;
    }

    .quiz-start-note {
        color: var(--color-muted);
        font-size: 0.85rem;
    }

    /* Highlighter: colours that follow the theme through their tokens. */
    mark.hl {
        color: inherit;
        -webkit-box-decoration-break: clone;
        box-decoration-break: clone;
    }

    mark[data-highlight] {
        cursor: pointer;
    }

    .hl-yellow {
        background: var(--hl-yellow);
    }

    .hl-green {
        background: var(--hl-green);
    }

    .hl-blue {
        background: var(--hl-blue);
    }

    .hl-pink {
        background: var(--hl-pink);
    }

    /* Links and inline code keep the highlight's contrast instead of their own colours. */
    .prose mark.hl a {
        color: inherit;
    }

    .prose mark.hl code {
        border-color: transparent;
        background: transparent;
    }

    /* Code blocks stay dark in both themes, so their highlights do too. */
    .code-block mark.hl,
    .code-block mark.hl * {
        color: var(--code-ink);
    }

    .code-block .hl-yellow {
        background: var(--code-hl-yellow);
    }

    .code-block .hl-green {
        background: var(--code-hl-green);
    }

    .code-block .hl-blue {
        background: var(--code-hl-blue);
    }

    .code-block .hl-pink {
        background: var(--code-hl-pink);
    }

    .hl-bar {
        position: fixed;
        z-index: 70;
        display: flex;
        align-items: center;
        gap: 0.15rem;
        padding: 0.25rem;
        border: 1px solid var(--color-line-strong);
        border-radius: 999px;
        background: var(--color-surface);
        box-shadow: 0 6px 24px rgb(0 0 0 / 0.2);
        touch-action: manipulation;
    }

    /* A phone shows its own selection menu by the text, so the bar waits at the bottom, clear of the top button. */
    @media (pointer: coarse) {
        .hl-bar {
            bottom: calc(env(safe-area-inset-bottom) + 76px);
            left: 50%;
            transform: translateX(-50%);
        }
    }

    .hl-swatch,
    .hl-remove {
        display: grid;
        place-items: center;
        width: 40px;
        height: 40px;
        border-radius: 50%;
        color: var(--color-muted);
        cursor: pointer;
    }

    .hl-swatch span {
        width: 24px;
        height: 24px;
        border: 1px solid var(--color-line-strong);
        border-radius: 50%;
        transition: transform var(--dur-snappy) var(--ease-snappy);
    }

    .hl-swatch:hover span {
        transform: scale(1.15);
    }

    .hl-swatch[aria-pressed="true"] span {
        outline: 2px solid var(--color-accent);
        outline-offset: 2px;
    }

    .hl-remove:hover {
        background: var(--color-sunken);
        color: var(--color-ink);
    }

    .hl-tools {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 0.6rem;
        margin-top: 1.1rem;
    }

    .hl-tool {
        padding-block: 0.45rem;
        padding-inline: 0.85rem;
        font-size: 0.88rem;
    }

    .hl-tool[aria-pressed="true"] {
        border-color: var(--color-line-strong);
        background: var(--hl-yellow);
        color: var(--color-ink);
    }

    .hl-tool:disabled {
        opacity: 0.5;
        cursor: not-allowed;
    }

    .hl-undo {
        border-color: var(--color-accent);
        color: var(--color-accent);
    }

    .hl-key {
        display: flex;
        flex-basis: 100%;
        flex-wrap: wrap;
        gap: 0.35rem 1.1rem;
        color: var(--color-muted);
        font-size: 0.82rem;
        list-style: none;
    }

    .hl-key li {
        display: inline-flex;
        align-items: center;
        gap: 0.4rem;
    }

    .hl-key span {
        width: 12px;
        height: 12px;
        border: 1px solid var(--color-line-strong);
        border-radius: 50%;
    }

    /* Code blocks — always dark, always left-to-right */
    .code-block {
        overflow: hidden;
        margin-block: 1.5em;
        border: 1px solid var(--code-line);
        border-radius: var(--radius-md);
        background: var(--code-bg);
        text-align: left;
    }

    .prose li > .code-block {
        margin-block: 0.85em 0.25em;
    }

    .code-bar {
        display: flex;
        align-items: center;
        justify-content: space-between;
        min-height: 40px;
        padding: 0.3rem 0.4rem 0.3rem 1rem;
        border-bottom: 1px solid var(--code-line);
        background: var(--code-bar);
    }

    .code-lang {
        color: var(--code-muted);
        font-family: var(--font-mono);
        font-size: 0.72rem;
        letter-spacing: 0.08em;
        text-transform: uppercase;
    }

    .copy-btn {
        display: inline-flex;
        align-items: center;
        gap: 0.35rem;
        height: 28px;
        padding-inline: 0.6rem;
        border-radius: 6px;
        color: var(--code-muted);
        font-family: var(--font-mono);
        font-size: 0.72rem;
        transition:
            color 150ms ease,
            background-color 150ms ease;
    }

    .copy-btn:hover {
        background: rgb(255 255 255 / 0.06);
        color: var(--code-ink);
    }

    .copy-btn .icon {
        width: 14px;
        height: 14px;
    }

    .copy-btn .icon-check,
    .copy-btn.is-copied .icon-copy {
        display: none;
    }

    .copy-btn.is-copied {
        color: var(--code-accent);
    }

    .copy-btn.is-copied .icon-check {
        display: block;
    }

    .code-block pre {
        scrollbar-width: thin;
        scrollbar-color: var(--code-line) transparent;
        margin: 0;
        padding: 1rem 1.15rem;
        overflow-x: auto;
        color: var(--code-ink);
        font-size: 0.85rem;
        line-height: 1.75;
        tab-size: 4;
    }

    .code-block pre:focus-visible {
        outline-offset: -2px;
    }

    .token.comment,
    .token.prolog,
    .token.doctype,
    .token.cdata {
        color: var(--code-comment);
    }

    .token.keyword,
    .token.boolean,
    .token.atrule,
    .token.section {
        color: var(--code-keyword);
    }

    .token.string,
    .token.char,
    .token.attr-value,
    .token.value {
        color: var(--code-string);
    }

    .token.number,
    .token.constant {
        color: var(--code-number);
    }

    .token.function,
    .token.builtin,
    .token.class-name {
        color: var(--code-function);
    }

    .token.variable,
    .token.property,
    .token.key,
    .token.attr-name,
    .token.parameter {
        color: var(--code-variable);
    }

    .token.operator,
    .token.punctuation {
        color: var(--code-operator);
    }
}

/* ---------- Series ---------- */
@layer components {
    .series-cards {
        display: grid;
        gap: 1rem;
    }

    .series-card {
        position: relative;
        display: grid;
        grid-template-columns: auto minmax(0, 1fr) 1.5rem;
        gap: 1.25rem;
        align-items: start;
        padding: clamp(1.25rem, 3vw, 1.75rem);
        border: 1px solid var(--color-line);
        border-radius: var(--radius-lg);
        background: var(--color-surface);
        transition:
            border-color 150ms ease,
            transform var(--dur-soft) var(--ease-soft);
    }

    .series-card:hover {
        border-color: var(--color-line-strong);
        transform: translateY(-2px);
    }

    .series-card .topic-icon {
        margin-bottom: 0;
    }

    .series-card:hover .topic-icon {
        background: var(--color-accent);
        color: var(--color-accent-ink);
    }

    .series-card-title {
        margin-top: 0.4rem;
        font-size: 1.3rem;
    }

    .series-card-title a::after {
        content: '';
        position: absolute;
        inset: 0;
        border-radius: inherit;
    }

    .series-card:hover .series-card-title a {
        color: var(--color-accent);
    }

    .series-card-text {
        margin-top: 0.4rem;
        max-width: 62ch;
        color: var(--color-muted);
        font-size: 0.97rem;
        line-height: 1.75;
    }

    .series-card:hover .post-row-arrow {
        opacity: 1;
        transform: none;
        color: var(--color-accent);
    }

    [dir="rtl"] .series-card:hover .post-row-arrow {
        transform: scaleX(-1);
    }

    .series-progress {
        display: flex;
        gap: 4px;
        margin-top: 1rem;
        max-width: 22rem;
    }

    .series-progress span {
        flex: 1;
        height: 4px;
        border-radius: 2px;
        background: var(--color-line);
    }

    .series-progress span.is-done {
        background: var(--color-accent);
    }

    /* Once a reader has started, the bar shows their own progress rather than what's published. */
    .has-progress .series-progress span.is-done {
        background: var(--color-line-strong);
    }

    .has-progress .series-progress span.is-started {
        background: color-mix(in srgb, var(--color-accent) 45%, var(--color-line));
    }

    .has-progress .series-progress span.is-read {
        background: var(--color-accent);
    }

    .series-status {
        max-width: 22rem;
        margin-top: 1.25rem;
    }

    .series-status .series-progress {
        margin-top: 0;
    }

    .series-status-row {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        justify-content: space-between;
        gap: 0 1rem;
    }

    .series-status-text {
        margin-top: 0.5rem;
        color: var(--color-muted);
        font-size: 0.85rem;
    }

    .series-status-row .series-status-text {
        margin-top: 0;
    }

    .series-status-count {
        color: var(--color-accent);
        font-family: var(--font-mono);
        font-weight: 600;
    }

    .series-status-reset {
        min-height: 44px;
        color: var(--color-faint);
        font-size: 0.82rem;
        cursor: pointer;
    }

    .series-status-reset:hover {
        color: var(--color-ink);
    }

    .series-status-reset.is-undo {
        color: var(--color-accent);
        font-weight: 600;
    }

    .series-label {
        color: var(--color-accent);
        font-weight: 600;
    }

    .series-label + .topic-label::before {
        content: '·';
        margin-inline-end: 0.9rem;
        color: var(--color-faint);
    }

    /* Badge above a series post's title */
    .series-badge {
        display: inline-flex;
        align-items: center;
        gap: 0.5rem;
        margin-top: 1.25rem;
        padding: 0.35rem 0.8rem 0.35rem 0.6rem;
        border: 1px solid color-mix(in srgb, var(--color-accent) 30%, transparent);
        border-radius: 999px;
        background: var(--color-accent-soft);
        color: var(--color-ink);
        font-size: 0.88rem;
        transition: border-color 150ms ease;
    }

    [dir="rtl"] .series-badge {
        padding: 0.35rem 0.6rem 0.35rem 0.8rem;
    }

    .series-badge:hover {
        border-color: var(--color-accent);
    }

    .series-badge .icon {
        width: 16px;
        height: 16px;
        color: var(--color-accent);
    }

    .series-badge strong {
        font-weight: 600;
    }

    .series-badge + .post-title {
        margin-top: 0.85rem;
    }

    /* Panel at the end of a series post */
    .series-panel {
        display: grid;
        gap: 1.25rem;
        margin-bottom: 2.5rem;
        padding: clamp(1.25rem, 3vw, 1.75rem);
        border: 1px solid var(--color-line);
        border-radius: var(--radius-lg);
        background: var(--color-surface);
    }

    .series-panel-title {
        display: block;
        margin-top: 0.35rem;
        font-size: 1.2rem;
        font-weight: 600;
    }

    .series-panel-title:hover {
        color: var(--color-accent);
    }

    .series-next {
        display: grid;
        gap: 0.3rem;
        padding: 1rem 1.15rem;
        border-radius: var(--radius-md);
        background: var(--color-ink);
        color: var(--color-bg);
        transition: transform var(--dur-snappy) var(--ease-snappy);
    }

    a.series-next:hover {
        transform: translateY(-2px);
    }

    .series-next.is-upcoming {
        background: var(--color-sunken);
        color: var(--color-muted);
    }

    .series-next-label {
        display: inline-flex;
        align-items: center;
        gap: 0.4rem;
        font-size: 0.82rem;
        opacity: 0.8;
    }

    .series-next-label .icon {
        width: 15px;
        height: 15px;
    }

    .series-next-title {
        font-size: 1.05rem;
        font-weight: 600;
        line-height: 1.5;
    }

    .series-mini-title {
        margin-bottom: 0.5rem;
        color: var(--color-muted);
        font-size: 0.85rem;
        font-weight: 600;
    }

    .series-mini {
        display: grid;
        gap: 0.15rem;
        list-style: none;
    }

    .series-mini li {
        position: relative;
        display: flex;
        gap: 0.75rem;
        align-items: baseline;
        padding: 0.4rem 0.6rem;
        border-radius: var(--radius-sm);
        font-size: 0.93rem;
        line-height: 1.5;
    }

    .series-mini a {
        color: var(--color-muted);
    }

    /* The whole row is the target, so it's easy to tap. */
    .series-mini a::after {
        content: '';
        position: absolute;
        inset: 0;
        border-radius: inherit;
    }

    .series-mini a:hover {
        color: var(--color-accent);
    }

    .series-mini li.is-current {
        background: var(--color-accent-soft);
        font-weight: 600;
    }

    .series-mini li.is-upcoming {
        color: var(--color-faint);
    }

    .series-mini-num {
        flex-shrink: 0;
        width: 1.5rem;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.78rem;
        text-align: center;
    }

    .series-mini li.is-current .series-mini-num {
        color: var(--color-accent);
    }

    .series-mini li.is-read .series-mini-num {
        align-self: center;
        height: 1rem;
        background: var(--color-accent);
        color: transparent;
        -webkit-mask: var(--mask-check) center / contain no-repeat;
        mask: var(--mask-check) center / contain no-repeat;
    }
}

@layer pages {
    /* Diagrams drawn inline in articles; colours come from the theme tokens. */
    .diagram {
        margin-block: 1.75em;
    }

    .diagram svg {
        width: 100%;
        height: auto;
        font-family: var(--font-sans);
    }

    .diagram figcaption {
        margin-top: 0.6rem;
        color: var(--color-muted);
        font-size: 0.88rem;
        text-align: center;
    }

    .diagram .d-title {
        fill: var(--color-ink);
        font-size: 18px;
        font-weight: 600;
    }

    .diagram .d-label {
        fill: var(--color-ink);
        font-size: 15px;
        font-weight: 600;
    }

    .diagram .d-code {
        fill: var(--color-muted);
        font-family: var(--font-mono);
        font-size: 12px;
    }

    .diagram .d-small {
        fill: var(--color-muted);
        font-size: 13px;
    }

    .blog-series {
        margin-block: 1.5rem 0.5rem;
    }

    /* Series page: jump list of sections, then the parts section by section */
    .series-index {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(min(270px, 100%), 1fr));
        gap: 0.5rem;
        list-style: none;
    }

    .series-index a {
        display: flex;
        align-items: baseline;
        gap: 0.6rem;
        padding: 0.65rem 0.9rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-md);
        background: var(--color-surface);
        font-size: 0.93rem;
        font-weight: 600;
        line-height: 1.5;
        transition: border-color 150ms ease;
    }

    .series-index a:hover {
        border-color: var(--color-accent);
    }

    .series-index-num {
        color: var(--color-accent);
        font-family: var(--font-mono);
        font-size: 0.78rem;
        font-weight: 600;
    }

    .series-index-count {
        margin-inline-start: auto;
        color: var(--color-faint);
        font-family: var(--font-mono);
        font-size: 0.75rem;
        white-space: nowrap;
    }

    .series-index-count.is-read {
        color: var(--color-accent);
        font-weight: 600;
    }

    .series-section {
        margin-top: 3rem;
        scroll-margin-top: 88px;
    }

    .series-section-title {
        display: flex;
        align-items: baseline;
        gap: 0.6rem;
        margin-bottom: 1rem;
        font-size: 1.3rem;
    }

    .series-section-num {
        color: var(--color-accent);
        font-family: var(--font-mono);
        font-size: 0.85rem;
        font-weight: 600;
    }

    .series-list {
        display: grid;
        gap: 0.75rem;
        list-style: none;
    }

    .series-item {
        position: relative;
        display: grid;
        grid-template-columns: 3rem minmax(0, 1fr) 1.5rem;
        gap: 1rem;
        align-items: start;
        padding: 1.25rem;
        border: 1px solid var(--color-line);
        border-radius: var(--radius-lg);
        background: var(--color-surface);
        transition: border-color 150ms ease;
    }

    .series-item:not(.is-upcoming):hover {
        border-color: var(--color-accent);
    }

    .series-item:not(.is-upcoming):hover .post-row-arrow {
        opacity: 1;
        transform: none;
        color: var(--color-accent);
    }

    [dir="rtl"] .series-item:not(.is-upcoming):hover .post-row-arrow {
        transform: scaleX(-1);
    }

    .series-num {
        display: grid;
        place-items: center;
        width: 3rem;
        height: 3rem;
        border-radius: var(--radius-md);
        background: var(--color-accent);
        color: var(--color-accent-ink);
        font-family: var(--font-mono);
        font-size: 1rem;
        font-weight: 600;
    }

    /* Once a reader has started: solid with a tick when finished, soft with the number until then. */
    .has-progress .series-item:not(.is-read, .is-upcoming) .series-num {
        background: var(--color-accent-soft);
        color: var(--color-accent);
    }

    .series-item.is-read .series-num {
        position: relative;
        color: transparent;
    }

    .series-item.is-read .series-num::before {
        content: '';
        position: absolute;
        inset: 0;
        margin: auto;
        width: 1.5rem;
        height: 1.5rem;
        background: var(--color-accent-ink);
        -webkit-mask: var(--mask-check) center / contain no-repeat;
        mask: var(--mask-check) center / contain no-repeat;
    }

    .series-item-status {
        margin-inline-start: 0.5rem;
        color: var(--color-accent);
        font-weight: 600;
    }

    /* Above the row's stretched link, so these don't open the part. */
    .series-item-clear,
    .series-item-confirm {
        display: inline-flex;
        flex-wrap: wrap;
        align-items: center;
    }

    .series-item-clear {
        position: relative;
        z-index: 1;
        margin-block: -0.6rem;
        color: var(--color-muted);
    }

    .series-item-answers {
        display: inline-flex;
    }

    .series-item-clear button {
        min-width: 44px;
        min-height: 44px;
        padding-inline: 0.5rem;
        color: var(--color-muted);
        text-decoration: underline;
        text-underline-offset: 2px;
    }

    .series-item-clear button:hover {
        color: var(--color-ink);
    }

    .series-item-clear button.is-yes {
        color: var(--color-accent);
        font-weight: 600;
    }

    .series-item.is-upcoming {
        border-style: dashed;
        background: transparent;
    }

    .series-item.is-upcoming .series-num {
        background: var(--color-sunken);
        color: var(--color-faint);
    }

    .series-item-title {
        font-size: 1.15rem;
        line-height: 1.5;
    }

    .series-item-title a::after {
        content: '';
        position: absolute;
        inset: 0;
        border-radius: inherit;
    }

    .series-item.is-upcoming .series-item-title {
        color: var(--color-muted);
        font-weight: 400;
    }

    .series-item-text {
        margin-top: 0.35rem;
        color: var(--color-muted);
        font-size: 0.95rem;
        line-height: 1.7;
    }

    .series-item-meta {
        display: inline-flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 0.35rem;
        margin-top: 0.5rem;
        color: var(--color-faint);
        font-size: 0.82rem;
    }

    .series-item-meta .icon {
        width: 14px;
        height: 14px;
    }
}

/* ---------- Utilities ---------- */
@layer utilities {
    /* Arabic labels: the mono face has no Arabic glyphs, and letter-spacing breaks Arabic joining. */
    :lang(ar) :is(.eyebrow, .topic-count, .chips-title, .toc-title, .footer-col h2, .post-nav-label, .copy-btn, .post-row-date, .code-lang, .series-section-num) {
        font-family: var(--font-sans);
        letter-spacing: 0;
        text-transform: none;
    }

    .visually-hidden {
        position: absolute !important;
        width: 1px;
        height: 1px;
        margin: -1px;
        padding: 0;
        overflow: hidden;
        clip: rect(0 0 0 0);
        white-space: nowrap;
        border: 0;
    }

    .center {
        text-align: center;
    }
}

/* ---------- Responsive (last layer, so breakpoints override every component) ---------- */
@layer responsive {
    @media (max-width: 960px) {
        .hero-grid {
            grid-template-columns: minmax(0, 1fr);
        }

        .footer-grid {
            grid-template-columns: repeat(3, 1fr);
        }

        .footer-brand {
            grid-column: 1 / -1;
        }
    }

    /* Below 820px the navigation becomes a panel under the header. The panel moves first;
       its links follow once it has room, and leave before it closes. */
    @media (max-width: 820px) {
        .menu-btn {
            display: inline-grid;
        }

        .site-nav {
            position: fixed;
            inset: 64px 0 0;
            z-index: 49;
            margin: 0;
            padding: 1.25rem clamp(16px, 4vw, 32px);
            background: var(--color-bg);
            border-top: 1px solid var(--color-line);
            visibility: hidden;
            opacity: 0;
            transform: translateY(-12px);
            transition:
                opacity 180ms ease 90ms,
                transform var(--dur-soft) var(--ease-soft) 90ms,
                visibility 0s linear calc(var(--dur-soft) + 90ms);
        }

        .site-nav.is-open {
            visibility: visible;
            opacity: 1;
            transform: none;
            transition:
                opacity 180ms ease,
                transform var(--dur-gentle) var(--ease-gentle),
                visibility 0s;
        }

        .nav-links {
            flex-direction: column;
            align-items: stretch;
            gap: 0;
        }

        .nav-links li {
            border-bottom: 1px solid var(--color-line);
        }

        .nav-link {
            padding: 1rem 0.25rem;
            border-radius: 0;
            color: var(--color-ink);
            font-size: 1.35rem;
            font-weight: 600;
            opacity: 0;
            transform: translateY(8px);
            transition:
                opacity 120ms ease,
                transform 120ms ease;
        }

        .site-nav.is-open .nav-link {
            opacity: 1;
            transform: none;
            transition:
                opacity 200ms ease,
                transform var(--dur-snappy) var(--ease-snappy);
        }

        .site-nav.is-open li:nth-child(1) .nav-link { transition-delay: 140ms; }
        .site-nav.is-open li:nth-child(2) .nav-link { transition-delay: 180ms; }
        .site-nav.is-open li:nth-child(3) .nav-link { transition-delay: 220ms; }
        .site-nav.is-open li:nth-child(4) .nav-link { transition-delay: 260ms; }

        .nav-link[aria-current="page"],
        .nav-links:not(.has-indicator) .nav-link[aria-current="page"] {
            background: none;
            color: var(--color-accent);
        }

        .nav-indicator {
            display: none;
        }

        .header-actions {
            margin-inline-start: auto;
        }
    }

    @media (max-width: 720px) {
        .post-row {
            grid-template-columns: minmax(0, 1fr);
            gap: 0.35rem;
        }

        .post-row-date {
            padding-top: 0;
        }

        .post-row-arrow {
            display: none;
        }

        .post-row::before {
            inset-inline: -0.6rem;
        }

        .post-nav {
            grid-template-columns: 1fr;
        }

        .series-card {
            grid-template-columns: minmax(0, 1fr);
        }

        .series-card .post-row-arrow {
            display: none;
        }

        .series-item {
            grid-template-columns: 2.5rem minmax(0, 1fr);
            padding: 1rem;
        }

        .series-item .post-row-arrow {
            display: none;
        }

        .series-num {
            width: 2.5rem;
            height: 2.5rem;
            font-size: 0.9rem;
        }

        .post-nav-link.is-newer {
            grid-column: auto;
        }

        .footer-grid {
            grid-template-columns: 1fr 1fr;
        }

        .author-card {
            flex-direction: column;
        }

        .section-head {
            flex-direction: column;
            align-items: flex-start;
        }
    }

    @media (max-width: 420px) {
        .header-actions .icon-btn[href*="#search"] {
            display: none;
        }

        .terminal-body {
            font-size: 0.72rem;
        }
    }
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        transition-duration: 0.01ms !important;
        transition-delay: 0s !important;
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        scroll-behavior: auto !important;
    }
}