/* Knowledge Hub — article (post-detail) page styles.
   Premium reading surface aligned to the chat overhaul + design-system tokens.
   Calm static background is handled by content_base.html; this file owns the
   reading column, sticky TOC rail, code-block chrome, byline, and related cards.
   Source of truth for the look: static/design-spikes/knowledge-hub-premium-reference.html */

    /* ── Design-system bridge (retarget local token names onto design-system.css) ── */
    :root {
        --color-bg-deep: var(--color-bg-primary);
        --color-bg: var(--color-bg-primary);
        --color-bg-elevated: var(--color-bg-secondary);
        --color-surface: var(--blur-bg);          /* dark translucent surface */
        --color-surface-solid: var(--color-bg-tertiary);
        --color-border-hover: var(--glass-border-hover);
        --color-text: var(--color-text-primary);
        --color-cyan: var(--color-accent-cyan);
        --color-cyan-dim: rgba(0, 242, 254, 0.6);
        --color-purple: #8b5cf6;
        --color-magenta: var(--color-accent-pink);
        --color-orange: var(--color-accent-gold);
        --font-display: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
        --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
        --font-mono: 'JetBrains Mono', monospace;
        --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
        --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
        --kh-ink: rgba(255, 255, 255, 0.92);      /* primary reading ink */
        --radius: 14px;                           /* local card radius (between --radius-lg/xl) */
    }

    /* ===== PAGE WRAPPER (calm background painted by content_base.html) ===== */
    .article-wrapper {
        position: relative;
        min-height: 100vh;
    }

    /* ===== READING PROGRESS ===== */
    .reading-progress {
        position: fixed;
        top: 0; left: 0; right: 0;
        height: 3px;
        z-index: var(--z-tooltip);
        pointer-events: none;
    }
    .reading-progress__bar {
        height: 100%;
        width: 0;
        background: linear-gradient(90deg, var(--color-accent-cyan), var(--color-accent-purple));
        box-shadow: 0 0 12px rgba(0, 242, 254, 0.45);
        transition: width 0.1s linear;
    }

    /* ===== SHELL: centered reading column + sticky TOC rail ===== */
    .article-shell {
        position: relative;
        z-index: 1;
        max-width: 1240px;
        margin: 0 auto;
        padding: 40px 32px 96px;
        display: grid;
        grid-template-columns: 1fr minmax(0, 720px) 1fr;
        column-gap: 0;
        /* NOTE: do NOT set align-items:start here. The grid must keep the default
           `stretch` so .toc-rail spans the full row height (= the article's
           height); that travel room is what lets .toc-rail__inner stay sticky as
           you scroll. align-items:start collapses the rail to content height and
           the sticky TOC scrolls away. Matches the design spike. */
    }
    .article-main { grid-column: 2; min-width: 0; }
    .toc-rail { grid-column: 3; }
    .toc-rail__inner { position: sticky; top: 96px; padding-left: 36px; }

    /* ===== BREADCRUMB ===== */
    .breadcrumb {
        display: flex;
        align-items: center;
        flex-wrap: wrap;
        gap: 10px;
        font-family: var(--font-body);
        font-size: 0.85rem;
        color: var(--color-text-muted);
        margin-bottom: 28px;
    }
    .breadcrumb a { color: var(--color-text-secondary); text-decoration: none; transition: color 0.15s var(--ease-out-expo); }
    .breadcrumb a:hover { color: var(--color-cyan); }
    .breadcrumb-sep { font-size: 0.65rem; color: var(--color-text-muted); }
    .breadcrumb-current { color: var(--color-text-muted); }

    /* ===== ARTICLE HERO (left-aligned) ===== */
    .article-hero { margin-bottom: 36px; }

    .article-eyebrow {
        display: inline-flex;
        align-items: center;
        gap: 8px;
        font-family: var(--font-body);
        font-size: 0.75rem;
        font-weight: 700;
        text-transform: uppercase;
        letter-spacing: 0.12em;
        color: var(--color-cyan);
        margin-bottom: 18px;
    }
    .eyebrow-dot {
        width: 7px; height: 7px;
        border-radius: 50%;
        background: var(--color-cyan);
        box-shadow: 0 0 10px var(--color-cyan);
    }

    .article-title {
        font-family: var(--font-display);
        color: var(--color-text);
        font-size: clamp(2rem, 4.5vw, 3rem);
        line-height: 1.12;
        margin: 0 0 24px;
        font-weight: 800;
        letter-spacing: -0.025em;
    }

    .article-meta {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 20px;
        font-family: var(--font-body);
        font-size: 0.9rem;
        color: var(--color-text-secondary);
    }
    .byline-chip { display: inline-flex; align-items: center; gap: 10px; }
    .byline-chip__avatar {
        width: 34px; height: 34px;
        border-radius: 50%;
        display: grid; place-items: center;
        font-size: 0.85rem; font-weight: 700;
        color: #03040c;
        background: linear-gradient(135deg, var(--color-cyan), var(--color-purple));
    }
    .byline-chip__name { font-weight: 600; color: var(--color-text); }
    .meta-sep { display: inline-flex; align-items: center; gap: 7px; color: var(--color-text-muted); }
    .meta-sep i { color: var(--color-cyan-dim); }

    /* ===== FEATURED IMAGE ===== */
    .article-featured-image {
        margin: 0 0 44px;
        border-radius: var(--radius-lg);
        overflow: hidden;
        border: 1px solid var(--color-border);
        box-shadow: 0 24px 50px -24px rgba(0, 0, 0, 0.7);
    }
    .featured-hero-image {
        width: 100%;
        height: auto;
        max-height: 460px;
        object-fit: cover;
        display: block;
    }

    /* ===== ARTICLE CONTENT (prose) ===== */
    .article-content {
        font-family: var(--font-body);
        font-size: 1.135rem;
        line-height: 1.78;
        color: var(--kh-ink);
    }
    .article-content > *:first-child { margin-top: 0; }

    .article-content h1,
    .article-content h2,
    .article-content h3,
    .article-content h4 {
        font-family: var(--font-display);
        color: var(--color-text);
        font-weight: 700;
        margin-top: 52px;
        margin-bottom: 22px;
        line-height: 1.3;
        letter-spacing: -0.015em;
        position: relative;
        scroll-margin-top: 90px;
    }
    .article-content h2 { font-size: 1.7rem; padding-left: 18px; }
    .article-content h2::before {
        content: '';
        position: absolute;
        left: 0;
        top: 0.18em;
        bottom: 0.18em;
        width: 4px;
        background: linear-gradient(180deg, var(--color-cyan), var(--color-purple));
        border-radius: 3px;
    }
    .article-content h3 { font-size: 1.34rem; }
    .article-content h4 { font-size: 1.16rem; }

    .article-content p { margin-bottom: 26px; }

    /* Lead paragraph — the opening paragraph reads larger, matching the design
       spike's editorial intro. :first-of-type catches the first prose paragraph
       wherever it lands (after any metadata header / first heading); helper
       blocks like references/disclaimer are nested, so they're never matched. */
    .article-content > p:first-of-type {
        font-size: clamp(1.15rem, 1.04rem + 0.5vw, 1.3rem);
        line-height: 1.62;
        color: var(--color-text-primary);
        margin-bottom: 32px;
    }

    .article-content a {
        color: var(--color-cyan);
        text-decoration: none;
        border-bottom: 1px solid rgba(0, 242, 254, 0.32);
        transition: border-color 0.15s var(--ease-out-expo);
    }
    .article-content a:hover { border-bottom-color: var(--color-cyan); }

    .article-content strong { color: #fff; font-weight: 700; }

    .article-content img {
        max-width: 100%;
        height: auto;
        border-radius: var(--radius-lg);
        margin: 36px 0;
        border: 1px solid var(--color-border);
        box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
    }

    /* blockquote / pull quote */
    .article-content blockquote {
        margin: 36px 0;
        padding: 24px 28px;
        border-left: 3px solid var(--color-cyan);
        border-radius: 0 var(--radius) var(--radius) 0;
        background: linear-gradient(120deg, rgba(0, 242, 254, 0.05), rgba(139, 92, 246, 0.04));
        backdrop-filter: blur(12px);
        font-style: italic;
        color: var(--color-text);
        font-size: 1.2rem;
        line-height: 1.6;
    }
    .article-content blockquote p:last-child { margin-bottom: 0; }

    /* inline code */
    .article-content code {
        font-family: var(--font-mono);
        font-size: 0.86em;
        color: var(--color-cyan);
        background: rgba(0, 242, 254, 0.08);
        border: 1px solid rgba(0, 242, 254, 0.16);
        border-radius: 6px;
        padding: 2px 7px;
    }

    /* bare <pre> (graceful look before JS adds window-chrome) */
    .article-content pre {
        background: #0b1020;
        padding: 18px;
        border-radius: var(--radius);
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        margin: 32px 0;
        border: 1px solid var(--color-border);
    }
    .article-content pre code {
        background: none;
        border: none;
        padding: 0;
        color: #d6e1ff;
        font-size: 0.85rem;
        line-height: 1.7;
        display: block;
    }

    /* ===== CODE BLOCK CHROME (knowledge-hub.js wraps <pre> in .code-block) ===== */
    .article-content .code-block {
        margin: 32px 0;
        border: 1px solid var(--color-border);
        border-radius: var(--radius);
        overflow: hidden;
        background: #0b1020;
    }
    .article-content .code-block pre {
        margin: 0;
        border: none;
        border-radius: 0;
        background: transparent;
    }
    .code-block__head {
        display: flex;
        align-items: center;
        gap: 10px;
        padding: 10px 14px;
        background: rgba(255, 255, 255, 0.025);
        border-bottom: 1px solid var(--color-border);
    }
    .code-dots { display: flex; gap: 7px; }
    .code-dots span { width: 11px; height: 11px; border-radius: 50%; }
    .code-dots span:nth-child(1) { background: #ff5f57; }
    .code-dots span:nth-child(2) { background: #febc2e; }
    .code-dots span:nth-child(3) { background: #28c840; }
    .code-lang {
        font-family: var(--font-mono);
        font-size: 11px;
        text-transform: uppercase;
        letter-spacing: 0.08em;
        color: var(--color-text-muted);
    }
    .code-copy {
        margin-left: auto;
        font-family: var(--font-body);
        font-size: 11.5px;
        font-weight: 600;
        color: var(--color-text-secondary);
        background: rgba(255, 255, 255, 0.05);
        border: 1px solid var(--color-border);
        border-radius: 7px;
        padding: 7px 12px;
        cursor: pointer;
        display: inline-flex;
        align-items: center;
        gap: 6px;
        transition: color 0.15s var(--ease-out-expo), background 0.15s var(--ease-out-expo), border-color 0.15s var(--ease-out-expo);
    }
    .code-copy:hover { color: var(--color-cyan); background: rgba(0, 242, 254, 0.08); border-color: var(--color-border-hover); }

    /* ===== SYNTAX HIGHLIGHTING (Prism token colors) =====
       Prism core + autoloader are loaded by article.html and add .token spans to
       `<code class="language-*">`. We deliberately load NO Prism theme stylesheet
       (its pre/code background + padding would fight the .code-block chrome) and
       provide the colors here instead, tuned to the brand palette so highlighted
       code matches the design spike. Unspecified tokens inherit the soft-blue
       (#d6e1ff) code text. Scoped to .article-content so it only touches posts. */
    .article-content .token.comment,
    .article-content .token.prolog,
    .article-content .token.doctype,
    .article-content .token.cdata { color: var(--color-text-muted); font-style: italic; }
    .article-content .token.punctuation { color: #9bb0d8; }
    .article-content .token.keyword,
    .article-content .token.boolean,
    .article-content .token.atrule,
    .article-content .token.important,
    .article-content .token.rule { color: #c792ea; }                 /* purple */
    .article-content .token.function,
    .article-content .token.class-name { color: var(--color-accent-cyan); }  /* cyan */
    .article-content .token.string,
    .article-content .token.char,
    .article-content .token.attr-value,
    .article-content .token.regex,
    .article-content .token.inserted { color: #c3e88d; }             /* green */
    .article-content .token.number,
    .article-content .token.constant,
    .article-content .token.symbol,
    .article-content .token.tag,
    .article-content .token.property,
    .article-content .token.deleted { color: #f78c6c; }              /* orange */
    .article-content .token.operator,
    .article-content .token.entity,
    .article-content .token.url { color: #89ddff; }
    .article-content .token.attr-name,
    .article-content .token.selector,
    .article-content .token.builtin { color: #82aaff; }
    .article-content .token.variable { color: #f07178; }

    /* lists */
    .article-content ul,
    .article-content ol { margin: 26px 0; padding-left: 4px; list-style: none; }
    .article-content li { position: relative; padding-left: 28px; margin-bottom: 12px; }
    .article-content ul li::before {
        content: '';
        position: absolute;
        left: 6px; top: 0.62em;
        width: 7px; height: 7px;
        background: var(--color-cyan);
        border-radius: 50%;
        box-shadow: 0 0 8px rgba(0, 242, 254, 0.5);
    }
    .article-content ol { counter-reset: list-counter; }
    .article-content ol li::before {
        counter-increment: list-counter;
        content: counter(list-counter);
        position: absolute;
        left: 0; top: 0.05em;
        width: 20px; height: 20px;
        background: linear-gradient(135deg, var(--color-cyan), var(--color-purple));
        border-radius: 6px;
        font-size: 0.7rem; font-weight: 700;
        color: #03040c;
        display: grid; place-items: center;
    }

    .article-content hr {
        border: none;
        height: 1px;
        background: linear-gradient(90deg, transparent, var(--color-border-hover), transparent);
        margin: 52px 0;
    }

    /* tables */
    .article-content table {
        width: 100%;
        margin: 32px 0;
        border-collapse: collapse;
        font-size: 0.95rem;
        display: block;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }
    .article-content table th {
        background: rgba(0, 242, 254, 0.06);
        color: var(--color-cyan);
        font-weight: 600;
        text-align: left;
        padding: 12px 16px;
        border-bottom: 1px solid var(--color-border);
    }
    .article-content table td { padding: 12px 16px; border-bottom: 1px solid var(--color-border); }
    .article-content table tbody tr:hover { background: rgba(255, 255, 255, 0.02); }
    .article-content table caption {
        caption-side: top;
        text-align: left;
        font-size: 0.9rem;
        color: var(--color-text-muted);
        padding: 8px 0;
        font-style: italic;
    }

    /* citations (render_markdown) */
    .article-content .citation-ref { font-size: 0.75em; line-height: 0; vertical-align: super; }
    .article-content .citation-ref a { color: var(--color-cyan); text-decoration: none; padding: 0 1px; transition: color 0.2s ease; }
    .article-content .citation-ref a:hover { color: var(--color-purple); text-decoration: underline; }

    /* references (render_markdown) */
    .article-content .references-section { margin-top: 52px; padding-top: 28px; border-top: 1px solid var(--color-border); }
    .article-content .references-section h2 { font-size: 1.4rem; margin-bottom: 18px; padding-left: 0; }
    .article-content .references-section h2::before { display: none; }
    .article-content .ref-entry { font-weight: 600; color: var(--color-cyan); margin-right: 4px; }
    .article-content .references-section p { padding-left: 2.5em; text-indent: -2.5em; font-size: 0.95rem; line-height: 1.6; margin-bottom: 8px; }

    /* disclaimer (render_markdown) */
    .article-content .doc-disclaimer { margin-top: 52px; padding: 22px 26px; background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius); font-size: 0.85rem; color: var(--color-text-muted); line-height: 1.6; }
    .article-content .doc-disclaimer h2 { font-size: 0.9rem; text-transform: uppercase; letter-spacing: 0.1em; margin-bottom: 8px; color: var(--color-text-muted); padding-left: 0; }
    .article-content .doc-disclaimer h2::before { display: none; }

    /* metadata header + author byline (render_markdown) */
    .article-content .doc-metadata-header { display: flex; align-items: center; gap: 12px; padding: 14px 22px; background: rgba(0, 242, 254, 0.05); border: 1px solid rgba(0, 242, 254, 0.15); border-radius: var(--radius); margin-bottom: 28px; font-size: 0.9rem; }
    .article-content .doc-brand { font-weight: 700; color: var(--color-cyan); font-family: var(--font-display); }
    .article-content .doc-date { color: var(--color-text-muted); }
    .article-content .doc-author { font-style: italic; color: var(--color-text-muted); margin-bottom: 32px; }

    /* server-side doc TOC (render_markdown [TOC]) — rare; client TOC uses .toc-rail */
    .article-content .doc-toc { background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius); padding: 22px 26px; margin-bottom: 40px; }
    .article-content .doc-toc h2 { font-size: 1.05rem; margin: 0 0 12px; padding-left: 0; }
    .article-content .doc-toc h2::before { display: none; }
    .article-content .doc-toc ol, .article-content .doc-toc ul { list-style: none; padding: 0; margin: 0; }
    .article-content .doc-toc li { padding: 6px 0; margin: 0; }
    .article-content .doc-toc li::before { display: none; }
    .article-content .toc-link { color: var(--color-text-secondary); text-decoration: none; font-size: 0.92rem; transition: color 0.15s var(--ease-out-expo); }
    .article-content .toc-link:hover { color: var(--color-cyan); }

    /* ===== TAGS + SHARE FOOT ===== */
    .article-foot {
        margin-top: 48px;
        padding-top: 28px;
        border-top: 1px solid var(--color-border);
        display: flex;
        flex-wrap: wrap;
        gap: 16px;
        align-items: center;
        justify-content: space-between;
    }
    .article-tags { display: flex; flex-wrap: wrap; gap: 8px; }
    .tag {
        font-family: var(--font-body);
        font-size: 0.82rem;
        color: var(--color-text-secondary);
        background: var(--color-surface);
        border: 1px solid var(--color-border);
        border-radius: 999px;
        padding: 6px 14px;
        text-decoration: none;
        transition: color 0.15s var(--ease-out-expo), border-color 0.15s var(--ease-out-expo);
    }
    .tag:hover { color: var(--color-cyan); border-color: var(--color-border-hover); }

    .article-share { display: flex; gap: 8px; }
    .article-share .share-btn {
        width: 40px; height: 40px;
        border-radius: 10px;
        display: grid; place-items: center;
        color: #fff;
        text-decoration: none;
        font-size: 0.95rem;
        transition: transform 0.15s var(--ease-out-expo), box-shadow 0.15s var(--ease-out-expo);
    }
    .article-share .share-btn:hover { transform: translateY(-3px); box-shadow: 0 12px 24px rgba(0, 0, 0, 0.35); }
    .article-share .share-x { background: #111418; border: 1px solid var(--color-border); }
    .article-share .share-linkedin { background: #0a66c2; }
    .article-share .share-reddit { background: #ff4500; }
    .article-share .share-email { background: var(--color-surface-solid); border: 1px solid var(--color-border); color: var(--color-text-secondary); }

    /* ===== AUTHOR BYLINE ===== */
    .article-byline {
        margin-top: 44px;
        display: flex;
        gap: 18px;
        align-items: flex-start;
        padding: 26px;
        background: var(--color-surface);
        border: 1px solid var(--color-border);
        border-radius: var(--radius-lg);
        backdrop-filter: blur(16px);
    }
    .byline-avatar {
        width: 56px; height: 56px;
        flex-shrink: 0;
        border-radius: 50%;
        display: grid; place-items: center;
        font-size: 1.25rem; font-weight: 700;
        color: #03040c;
        background: linear-gradient(135deg, var(--color-cyan), var(--color-purple));
    }
    .byline-info .byline-name { font-family: var(--font-display); font-size: 1.05rem; font-weight: 700; margin: 0 0 3px; color: var(--color-text); }
    .byline-info .byline-role { font-size: 0.82rem; color: var(--color-cyan); font-weight: 600; margin-bottom: 10px; }
    .byline-info p { font-size: 0.92rem; color: var(--color-text-secondary); line-height: 1.6; margin: 0; }

    /* ===== RELATED ARTICLES ===== */
    .related-articles { margin-top: 56px; }
    .related-heading {
        font-family: var(--font-display);
        font-size: 1.4rem;
        font-weight: 700;
        margin: 0 0 24px;
        display: flex;
        align-items: center;
        gap: 12px;
        color: var(--color-text);
    }
    .related-heading i {
        width: 38px; height: 38px;
        border-radius: 10px;
        display: grid; place-items: center;
        font-size: 0.95rem;
        color: var(--color-cyan);
        background: rgba(0, 242, 254, 0.08);
        border: 1px solid rgba(0, 242, 254, 0.2);
    }
    .related-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
    .related-card {
        background: var(--color-surface);
        border: 1px solid var(--color-border);
        border-radius: var(--radius);
        overflow: hidden;
        text-decoration: none;
        color: inherit;
        transition: transform 0.3s var(--ease-out-expo), border-color 0.3s var(--ease-out-expo), box-shadow 0.3s var(--ease-out-expo);
    }
    .related-card:hover { transform: translateY(-5px); border-color: var(--color-border-hover); box-shadow: 0 22px 44px -22px rgba(0, 0, 0, 0.7); }
    .related-card__thumb {
        height: 120px;
        position: relative;
        overflow: hidden;
        background: linear-gradient(135deg, #182048 0%, #241a44 100%); /* no-image fallback */
        display: grid; place-items: center;
    }
    .related-card__thumb img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
    .related-card__thumb i { font-size: 1.4rem; color: rgba(0, 242, 254, 0.25); }
    .related-card__body { padding: 16px 18px; }
    .related-card h3 { font-family: var(--font-display); font-size: 0.98rem; font-weight: 600; line-height: 1.35; margin: 0 0 8px; color: var(--color-text); transition: color 0.2s var(--ease-out-expo); }
    .related-card:hover h3 { color: var(--color-cyan); }
    .related-card__meta { font-size: 0.78rem; color: var(--color-text-muted); }

    /* ===== BACK TO BLOG ===== */
    .back-to-blog {
        display: inline-flex;
        align-items: center;
        gap: 12px;
        font-family: var(--font-body);
        color: var(--color-text-secondary);
        text-decoration: none;
        font-size: 0.9rem;
        font-weight: 600;
        margin-top: 48px;
        padding: 12px 24px;
        background: var(--color-surface);
        backdrop-filter: blur(10px);
        border-radius: 999px;
        border: 1px solid var(--color-border);
        transition: color 0.18s var(--ease-out-expo), border-color 0.18s var(--ease-out-expo), transform 0.18s var(--ease-out-expo);
    }
    .back-to-blog:hover { color: var(--color-cyan); border-color: var(--color-border-hover); transform: translateX(-4px); }
    .back-to-blog i { transition: transform 0.25s var(--ease-spring); }
    .back-to-blog:hover i { transform: translateX(-4px); }

    /* ===== STICKY TOC RAIL (client-built by knowledge-hub.js) ===== */
    .article-toc__title {
        font-family: var(--font-body);
        font-size: 11px;
        font-weight: 700;
        text-transform: uppercase;
        letter-spacing: 0.1em;
        color: var(--color-text-muted);
        margin: 0 0 14px;
    }
    .article-toc ul { list-style: none; margin: 0; padding: 0; }
    .article-toc li { margin: 0; }
    .article-toc li.toc-h3 a { padding-left: 28px; font-size: 0.82rem; }
    .article-toc a {
        display: block;
        padding: 7px 0 7px 14px;
        font-size: 0.86rem;
        line-height: 1.4;
        color: var(--color-text-secondary);
        text-decoration: none;
        border-left: 2px solid var(--color-border);
        transition: color 0.15s var(--ease-out-expo), border-color 0.15s var(--ease-out-expo);
    }
    .article-toc a:hover { color: var(--color-text); }
    .article-toc a.is-active { color: var(--color-cyan); border-left-color: var(--color-cyan); }

    /* ===== ACCESSIBILITY: keyboard focus ===== */
    .breadcrumb a:focus-visible,
    .article-content a:focus-visible,
    .tag:focus-visible,
    .article-share .share-btn:focus-visible,
    .related-card:focus-visible,
    .back-to-blog:focus-visible,
    .code-copy:focus-visible,
    .article-toc a:focus-visible {
        outline: 2px solid var(--color-accent-cyan);
        outline-offset: 3px;
    }

    /* ===== SHELL COLLAPSE (TOC rail folds away below desktop) ===== */
    @media (max-width: 1100px) {
        .article-shell { grid-template-columns: 1fr; max-width: 760px; }
        .article-main, .toc-rail { grid-column: 1; }
        .toc-rail { display: none; }
    }

    /* ===== ACCESSIBILITY: reduced motion ===== */
    @media (prefers-reduced-motion: reduce) {
        .reading-progress__bar,
        .related-card,
        .article-share .share-btn,
        .back-to-blog,
        .back-to-blog i,
        .tag,
        .code-copy,
        .article-content a {
            transition: none;
        }
        .related-card:hover,
        .article-share .share-btn:hover,
        .back-to-blog:hover,
        .back-to-blog:hover i { transform: none; }
    }