*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

        :root {
            --bg: #fafaf9;
            --surface: #ffffff;
            --text: #1c1917;
            --text-secondary: #57534e;
            --text-muted: #a8a29e;
            --primary: #4f46e5;
            --primary-hover: #4338ca;
            --accent: #d97706;
            --border: #e7e5e4;
            --radius: 10px;
            --shadow-sm: 0 1px 3px rgba(0,0,0,.06);
            --shadow-md: 0 4px 16px rgba(0,0,0,.08);
            --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
            --font-mono: "SF Mono", "Fira Code", "Cascadia Code", Consolas, monospace;
        }

        html { font-size: 16px; scroll-behavior: smooth; }

        body {
            font-family: var(--font-sans);
            background: var(--bg);
            color: var(--text);
            line-height: 1.7;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            -webkit-font-smoothing: antialiased;
            -moz-osx-font-smoothing: grayscale;
        }

        /* ── Inline Back ── */
        .top-bar {
            max-width: 960px;
            width: 100%;
            margin: 0 auto;
            padding: 20px 20px 0;
            display: flex;
            align-items: center;
            gap: 12px;
        }
        .back-link {
            display: inline-flex;
            align-items: center;
            gap: 6px;
            padding: 6px 14px;
            font-size: .82rem;
            font-weight: 500;
            color: var(--text-secondary);
            text-decoration: none;
            border-radius: 20px;
            border: 1px solid var(--border);
            transition: all .15s ease;
            font-family: var(--font-mono);
            white-space: nowrap;
        }
        .back-link:hover {
            color: var(--primary);
            border-color: var(--primary);
            background: rgba(79,70,229,.04);
        }
        .top-title {
            font-size: .85rem;
            color: var(--text-muted);
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
            font-family: var(--font-mono);
        }

        /* ── Article Header ── */
        .article-header {
            max-width: 960px;
            width: 100%;
            margin: 28px auto 24px;
            padding: 0 20px;
        }
        .article-title {
            font-size: 1.85rem;
            font-weight: 800;
            color: var(--text);
            line-height: 1.35;
            letter-spacing: -.02em;
            margin-bottom: 14px;
        }
        .article-meta {
            display: flex;
            gap: 8px;
            flex-wrap: wrap;
            align-items: center;
        }
        .meta-tag {
            display: inline-block;
            padding: 4px 12px;
            font-size: .78rem;
            color: var(--text-secondary);
            background: var(--surface);
            border: 1px solid var(--border);
            border-radius: 20px;
            font-family: var(--font-mono);
        }
        .meta-download {
            display: inline-flex;
            align-items: center;
            gap: 4px;
            padding: 4px 14px;
            font-size: .78rem;
            font-weight: 600;
            color: #fff;
            background: var(--primary);
            border: none;
            border-radius: 20px;
            font-family: var(--font-mono);
            text-decoration: none;
            transition: background .15s;
            margin-left: auto;
        }
        .meta-download:hover { background: var(--primary-hover); color: #fff; }

        /* ── Content ── */
        .article-body {
            max-width: 960px;
            width: 100%;
            margin: 0 auto;
            padding: 0 20px 60px;
            flex: 1;
        }
        .content-card {
            background: var(--surface);
            border: 1px solid var(--border);
            border-radius: var(--radius);
            padding: 36px 40px;
            box-shadow: var(--shadow-sm);
            overflow-wrap: break-word;
            word-break: break-word;
        }

        /* ── Markdown Typography ── */
        .content-card h1 { font-size: 1.7rem; font-weight: 800; margin: 32px 0 16px; padding-bottom: 10px; border-bottom: 2px solid var(--border); letter-spacing: -.01em; scroll-margin-top: 20px; }
        .content-card h2 { font-size: 1.4rem; font-weight: 700; margin: 28px 0 14px; padding-bottom: 8px; border-bottom: 1px solid var(--border); scroll-margin-top: 20px; }
        .content-card h3 { font-size: 1.2rem; font-weight: 700; margin: 24px 0 12px; scroll-margin-top: 20px; }
        .content-card h4 { font-size: 1.05rem; font-weight: 700; margin: 20px 0 10px; scroll-margin-top: 20px; }
        .content-card h5, .content-card h6 { font-size: .95rem; font-weight: 700; margin: 16px 0 8px; color: var(--text-secondary); scroll-margin-top: 20px; }
        .content-card p { margin: 14px 0; line-height: 1.85; }
        .content-card ul, .content-card ol { margin: 14px 0; padding-left: 24px; }
        .content-card li { margin: 5px 0; line-height: 1.8; }
        .content-card blockquote { border-left: 3px solid var(--accent); padding: 12px 20px; margin: 18px 0; background: rgba(217,119,6,.04); color: var(--text-secondary); border-radius: 0 var(--radius) var(--radius) 0; }
        .content-card blockquote p { margin: 4px 0; }
        .content-card pre { padding: 18px 20px; margin: 18px 0; border-radius: var(--radius); overflow-x: auto; font-family: var(--font-mono); font-size: .9rem; line-height: 1.7; -webkit-overflow-scrolling: touch; position: relative; background: #282c34; color: #abb2bf; box-shadow: 0 2px 8px rgba(0,0,0,.08); }
        .code-copy-btn { position: absolute; top: 8px; right: 8px; padding: 4px 12px; font-size: .75rem; font-family: var(--font-mono); color: #9da5b4; background: rgba(255,255,255,.08); border: 1px solid #3e4451; border-radius: 5px; cursor: pointer; transition: all .15s; opacity: 0; z-index: 2; }
        .content-card pre:hover .code-copy-btn { opacity: 1; }
        .code-copy-btn:hover { color: #fff; background: rgba(255,255,255,.15); border-color: #5c6370; }
        .code-copy-btn.copied { color: #98c379; border-color: #98c379; }
        .content-card pre code { background: none; padding: 0; color: inherit; font-size: inherit; }
        .content-card pre code.hljs { padding: 0; background: transparent; }
        .content-card code { background: rgba(79,70,229,.08); padding: 2px 8px; border-radius: 4px; font-family: var(--font-mono); font-size: .88rem; color: var(--primary); }
        .content-card img { max-width: 100%; height: auto; margin: 18px 0; border-radius: var(--radius); border: 1px solid var(--border); }
        .content-card a { color: var(--primary); text-decoration: none; border-bottom: 1px solid transparent; transition: border-color .15s; }
        .content-card a:hover { border-bottom-color: var(--primary); }
        .content-card hr { border: none; border-top: 1px solid var(--border); margin: 32px 0; }
        .content-card strong { font-weight: 700; }
        .content-card del { color: var(--text-muted); }
        .content-card table { border-collapse: collapse; width: 100%; margin: 18px 0; font-size: .9rem; }
        .content-card th, .content-card td { border: 1px solid var(--border); padding: 10px 14px; text-align: left; }
        .content-card th { background: var(--bg); font-weight: 600; }
        .content-card .task-list { list-style: none; padding-left: 4px; }
        .content-card .task-list-item { display: flex; align-items: flex-start; gap: 8px; margin: 5px 0; line-height: 1.8; }
        .content-card .task-list-item input[type="checkbox"] { margin-top: 5px; width: 16px; height: 16px; accent-color: var(--primary); cursor: default; flex-shrink: 0; }
        .content-card .footnotes { margin-top: 32px; padding-top: 16px; border-top: 1px solid var(--border); font-size: .88rem; color: var(--text-secondary); }
        .content-card .footnotes ol { padding-left: 24px; }
        .content-card .footnotes li { margin: 6px 0; line-height: 1.7; }
        .content-card .footnote-ref { font-size: .78em; vertical-align: super; color: var(--primary); text-decoration: none; font-weight: 600; }
        .content-card .footnote-backref { color: var(--text-muted); text-decoration: none; font-size: .85em; }
        .content-card .footnote-backref:hover { color: var(--primary); }

        /* ── Source Link ── */
        .source-bar { max-width: 960px; width: 100%; margin: 0 auto 40px; padding: 0 20px; }
        .source-link { display: inline-flex; align-items: center; gap: 6px; padding: 10px 18px; font-size: .85rem; font-family: var(--font-mono); background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); color: var(--primary); text-decoration: none; transition: all .15s; }
        .source-link:hover { border-color: var(--primary); background: rgba(79,70,229,.04); }

        /* ── Back to Top ── */
        .back-top { position: fixed; bottom: 24px; right: 24px; width: 44px; height: 44px; background: var(--surface); border: 1px solid var(--border); border-radius: 10px; color: var(--text-secondary); display: none; align-items: center; justify-content: center; cursor: pointer; font-size: 1.1rem; transition: all .2s ease; z-index: 50; box-shadow: var(--shadow-sm); }
        .back-top.visible { display: flex; }
        .back-top:hover { border-color: var(--primary); color: var(--primary); background: rgba(79,70,229,.04); transform: translateY(-2px); }

        /* ── Footer ── */
        .site-footer { text-align: center; padding: 22px 20px; font-size: .78rem; color: var(--text-muted); border-top: 1px solid var(--border); font-family: var(--font-mono); margin-top: auto; }
        .footer-meta { display: flex; flex-wrap: wrap; justify-content: center; align-items: center; gap: 6px 16px; line-height: 1.8; }
        .site-footer a { color: var(--text-secondary); text-decoration: none; transition: color .15s; }
        .site-footer a:hover { color: var(--primary); }

        /* ── Responsive ── */
        @media (max-width: 640px) {
            html { font-size: 15px; }
            .top-bar { padding: 16px 16px 0; }
            .back-link { padding: 6px 12px; font-size: .85rem; }
            .top-title { max-width: 160px; font-size: .85rem; }
            .article-header { margin: 20px auto 18px; padding: 0 16px; }
            .article-title { font-size: 1.5rem; }
            .article-meta { gap: 6px; }
            .meta-tag { padding: 4px 10px; font-size: .8rem; }
            .meta-download { padding: 4px 12px; font-size: .78rem; }
            .article-body { padding: 0 16px 40px; }
            .content-card { padding: 24px 18px; }
            .content-card h1 { font-size: 1.4rem; }
            .content-card h2 { font-size: 1.2rem; }
            .content-card h3 { font-size: 1.1rem; }
            .content-card p { font-size: 1rem; line-height: 1.9; }
            .content-card pre { padding: 14px 16px; font-size: .85rem; }
            .content-card code { font-size: .85rem; }
            .content-card table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }
            .content-card th, .content-card td { white-space: nowrap; padding: 9px 12px; }
            .content-card ul, .content-card ol { padding-left: 20px; }
            .content-card blockquote { padding: 10px 14px; }
            .source-bar { padding: 0 16px; }
            .source-link { padding: 10px 14px; font-size: .85rem; }
            .back-top { width: 40px; height: 40px; bottom: 20px; right: 20px; }
        }

        @media (min-width: 641px) and (max-width: 1024px) {
            .article-header, .article-body, .source-bar { padding-left: 24px; padding-right: 24px; }
            .content-card { padding: 32px 32px; }
        }

        @media print {
            .top-bar, .back-top, .source-bar, .site-footer { display: none; }
            .content-card { border: none; box-shadow: none; padding: 0; }
            .article-header { margin-top: 0; }
            body { background: #fff; }
        }

        @media (prefers-reduced-motion: reduce) {
            *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
            html { scroll-behavior: auto; }
        }