/* 1. 默认：浅色主题（Light Mode）变量 */
        :root {
            --primary-color: #4f46e5;
            --text-color: #1f2937;
            --text-secondary: #6b7280;
            --text-muted: #9ca3af;
            --bg-color: #f9fafb;
            --card-bg: #ffffff;
            --border-color: #e5e7eb;
            --warning-bg: #fef2f2;
            --warning-border: #fecaca;
            --warning-text: #991b1b;
        }

        /* 2. 自动跟随系统：暗黑主题（Dark Mode）变量重写 */
        @media (prefers-color-scheme: dark) {
            :root {
                --primary-color: #818cf8;
                --text-color: #f3f4f6;
                --text-secondary: #9ca3af;
                --text-muted: #6b7280;
                --bg-color: #111827;
                --card-bg: #1f2937;
                --border-color: #374151;
                --warning-bg: #451a03;
                --warning-border: #78350f;
                --warning-text: #fcd34d;
            }
        }

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

        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
            color: var(--text-color);
            background-color: var(--bg-color);
            line-height: 1.6;
            padding: 0;
            transition: background-color 0.3s ease, color 0.3s ease;
        }

        [dir="rtl"] body {
            font-family: "Geeza Pro", "Tahoma", "Arial", sans-serif;
        }

        .site-header { border-bottom: 1px solid var(--border-color); }
        .site-header a { display: block; max-width: 880px; margin-inline: auto; padding: 22px 28px; color: var(--text-color); font-size: 12px; font-weight: 650; letter-spacing: .16em; text-decoration: none; }
        .container {
            max-width: 760px;
            margin: 0 auto;
            background: transparent;
            padding: 64px 28px 72px;
            transition: background-color 0.3s ease, border-color 0.3s ease;
        }

        .top-bar {
            display: flex;
            justify-content: space-between;
            align-items: flex-start;
            gap: 20px;
            margin-bottom: 38px;
        }

        .header {
            flex: 1;
            text-align: start;
        }

        .header h1 {
            font-size: clamp(30px, 5vw, 44px);
            line-height: 1.12;
            color: var(--text-color);
            margin-bottom: 8px;
        }

        .header p {
            font-size: 14px;
            color: var(--text-secondary);
        }

        .section {
            margin-bottom: 24px;
        }

        .section h2 {
            font-size: 18px;
            margin-bottom: 12px;
            color: var(--primary-color);
            border-bottom: 2px solid var(--border-color);
            padding-bottom: 6px;
        }

        .section p,
        .section li {
            font-size: 14px;
            color: var(--text-secondary);
            margin-bottom: 8px;
        }

        .section ul,
        .section ol {
            padding-inline-start: 20px;
        }

        .section strong {
            color: var(--text-color);
        }

        .protocol-footer { border-top: 1px solid var(--border-color); color: var(--text-muted); font-size: 12px; }
        .footer-inner { max-width: 880px; margin-inline: auto; padding: 25px 28px 34px; display: flex; align-items: center; justify-content: space-between; gap: 18px; }
        .switcher { position: relative; }
        .switcher summary { list-style: none; cursor: pointer; color: var(--text-secondary); padding: 8px 0; }
        .switcher summary::after { content: "⌄"; margin-inline-start: 7px; }
        .switcher summary::-webkit-details-marker { display: none; }
        .switcher ul { position: absolute; inset-inline-end: 0; bottom: calc(100% + 6px); min-width: 170px; max-height: 280px; overflow: auto; list-style: none; padding: 6px; background: var(--card-bg); border: 1px solid var(--border-color); border-radius: 8px; box-shadow: 0 16px 36px rgba(0,0,0,.14); }
        .switcher a { display: block; padding: 7px 9px; border-radius: 5px; color: var(--text-secondary); text-decoration: none; white-space: nowrap; }
        .switcher a:hover,.switcher a[aria-current] { color: var(--text-color); background: color-mix(in srgb, var(--primary-color) 10%, transparent); }
        .footer-select { max-width: 180px; border: 0; background: transparent; color: var(--text-muted); font: inherit; font-size: 12px; padding: 8px 22px 8px 4px; cursor: pointer; color-scheme: light dark; }
        .footer-select:focus { outline: 1px solid var(--border-color); outline-offset: 4px; border-radius: 3px; }

        @media (max-width: 650px) {
            .container { padding: 42px 20px 56px; }
            .top-bar {
                flex-direction: column-reverse;
                align-items: stretch;
                gap: 15px;
            }
            .footer-inner { padding-inline: 20px; align-items: flex-start; flex-direction: column; }
        }

        .alert-box {
            background-color: var(--warning-bg);
            border: 1px solid var(--warning-border);
            border-radius: 8px;
            padding: 16px;
            margin-bottom: 24px;
            color: var(--warning-text);
            font-size: 14px;
        }