:root {
    --primary: #10b981;
    --primary-dark: #059669;
    --primary-soft: #d1fae5;
    --primary-light: #ecfdf5;
    --slate-900: #0f172a;
    --slate-800: #1e293b;
    --slate-700: #334155;
    --slate-500: #64748b;
    --slate-300: #cbd5e1;
    --slate-100: #f1f5f9;
    --white: #ffffff;
    --radius-lg: 16px;
    --radius-md: 12px;
    --radius-sm: 8px;
    --shadow-card: 0 4px 6px -1px rgba(0,0,0,0.05), 0 2px 4px -2px rgba(0,0,0,0.05);
    --shadow-hover: 0 10px 15px -3px rgba(5,150,105,0.08), 0 4px 6px -4px rgba(5,150,105,0.04);
    --transition: 0.2s ease;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif;
    color: var(--slate-800); line-height: 1.6; background: #fff;
    -webkit-font-smoothing: antialiased;
}

/* ----- 头部导航（复用首页风格） ----- */
header { position: sticky; top: 0; background: rgba(255,255,255,0.92); backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); border-bottom: 1px solid var(--slate-300); z-index: 1000; }
.header-box { max-width: 1200px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; padding: 14px 24px; gap: 20px; }
.brand-logo { display: flex; align-items: center; gap: 10px; text-decoration: none; color: var(--slate-900); font-weight: 700; font-size: 1.35rem; letter-spacing: -0.3px; white-space: nowrap; }
.brand-logo img { width: 36px; height: 36px; }
nav { display: flex; align-items: center; gap: 28px; flex-wrap: wrap; }
nav a { text-decoration: none; color: var(--slate-700); font-size: 0.95rem; font-weight: 500; transition: color var(--transition); white-space: nowrap; }
nav a:hover { color: var(--primary-dark); }
nav a.current-tab { color: var(--primary); font-weight: 600; border-bottom: 2px solid var(--primary); padding-bottom: 4px; }
.nav-accent { background: var(--primary); color: #fff !important; padding: 8px 18px; border-radius: 20px; font-size: 0.9rem; transition: background var(--transition); }
.nav-accent:hover { background: var(--primary-dark); }

/* ----- 下载Hero面板 ----- */
.dl-hero-panel { padding: 60px 24px 40px; text-align: center; background: linear-gradient(180deg, #f8fafc 0%, #fff 100%); }
.dl-hero-panel h1 { font-size: clamp(2rem, 5vw, 2.8rem); color: var(--slate-900); margin-bottom: 16px; letter-spacing: -0.6px; }
.dl-hero-panel p { font-size: 1.1rem; color: var(--slate-500); max-width: 800px; margin: 0 auto 30px; }
.hero-quick-links { display: flex; justify-content: center; gap: 16px; flex-wrap: wrap; }
.quick-link-card { background: var(--white); border: 1px solid var(--slate-300); padding: 10px 24px; border-radius: 30px; text-decoration: none; color: var(--slate-700); font-weight: 600; transition: all var(--transition); }
.quick-link-card:hover { border-color: var(--primary); color: var(--primary); background: var(--primary-light); }

/* ----- 非对称布局容器 ----- */
.asymmetric-layout-container { max-width: 1200px; margin: 30px auto 60px; padding: 0 24px; display: flex; flex-direction: column; gap: 30px; }

/* 桌面双卡片行 */
.desktop-premium-row { display: grid; grid-template-columns: 1.2fr 1fr; gap: 30px; }

/* 移动端双卡片行 */
.mobile-split-row { display: grid; grid-template-columns: repeat(2, 1fr); gap: 30px; }

/* 通用下载卡片 */
.dl-asym-card {
    background: #fff; border: 1px solid var(--slate-300); border-radius: var(--radius-lg);
    padding: 30px; display: flex; flex-direction: column; justify-content: space-between;
    position: relative; overflow: hidden;
}
.dl-asym-card.featured-card { border: 2px solid var(--primary); background-image: radial-gradient(circle at top right, var(--primary-light), transparent 60%); }
.card-badge-top { position: absolute; top: 15px; right: 15px; background: var(--primary); color: #fff; font-size: 0.75rem; font-weight: 700; padding: 4px 10px; border-radius: 20px; text-transform: uppercase; }
.platform-header { display: flex; align-items: center; gap: 14px; margin-bottom: 16px; }
.platform-header svg { width: 36px; height: 36px; fill: var(--primary); }
.platform-header h2 { font-size: 1.4rem; color: var(--slate-900); letter-spacing: -0.3px; }
.platform-intro-text { font-size: 1rem; color: var(--slate-700); margin-bottom: 20px; line-height: 1.6; }
.meta-spec-table { background: var(--slate-100); border-radius: var(--radius-sm); padding: 16px; margin-bottom: 20px; font-size: 0.88rem; border: 1px solid #e2e8f0; }
.meta-spec-item { display: flex; justify-content: space-between; padding: 6px 0; border-bottom: 1px dashed var(--slate-300); }
.meta-spec-item:last-child { border-bottom: none; }
.meta-spec-label { color: var(--slate-500); }
.meta-spec-value { color: var(--slate-800); font-family: ui-monospace, monospace; font-weight: 500; }
.version-highlight { background: #fff; border: 1px solid var(--primary-soft); padding: 12px; border-radius: var(--radius-sm); margin-bottom: 20px; font-size: 0.9rem; color: var(--slate-700); }
.version-highlight strong { color: var(--primary-dark); }

.trigger-download-anchor {
    display: flex; align-items: center; justify-content: center; gap: 8px;
    background: var(--slate-900); color: #fff; text-decoration: none;
    padding: 14px 24px; border-radius: var(--radius-sm); font-weight: 600;
    transition: background var(--transition); margin-bottom: 10px; text-align: center;
}
.featured-card .trigger-download-anchor { background: var(--primary); }
.featured-card .trigger-download-anchor:hover { background: var(--primary-dark); }
.trigger-download-anchor:hover { background: var(--slate-800); }
.mirror-link { font-size: 0.9rem; color: var(--slate-500); text-decoration: none; text-align: center; display: block; }
.mirror-link:hover { color: var(--primary); }
.alt-store-note { font-size: 0.85rem; color: var(--slate-500); margin-top: 10px; text-align: center; }

/* Linux 核心横幅区 */
.standalone-core-belt {
    background: var(--slate-900); color: #fff; border-radius: var(--radius-lg);
    padding: 30px; display: flex; align-items: center; justify-content: space-between;
    gap: 30px; flex-wrap: wrap;
}
.core-belt-text h3 { font-size: 1.3rem; color: #fff; margin-bottom: 6px; }
.core-belt-text p { font-size: 0.95rem; color: #94a3b8; max-width: 500px; }
.core-actions-cluster { display: flex; gap: 16px; flex-wrap: wrap; }
.belt-action-btn {
    background: var(--slate-700); color: #fff; text-decoration: none;
    padding: 10px 20px; border-radius: var(--radius-sm); font-weight: 600;
    font-size: 0.9rem; border: 1px solid var(--slate-500); transition: all var(--transition);
}
.belt-action-btn:hover { background: var(--primary); border-color: var(--primary); }

/* 安装检查清单 */
.install-checklist { background: #fff; border: 1px solid var(--slate-300); border-radius: var(--radius-lg); padding: 40px; }
.install-checklist h2 { font-size: 1.8rem; text-align: center; margin-bottom: 8px; }
.section-sub { text-align: center; color: var(--slate-500); margin-bottom: 30px; }
.checklist-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; }
.checklist-item { display: flex; gap: 12px; background: var(--slate-100); padding: 14px; border-radius: var(--radius-sm); align-items: baseline; font-size: 0.95rem; color: var(--slate-700); }
.check-icon { flex-shrink: 0; }

/* 版本日志预览 */
.changelog-preview { padding: 40px; background: #fff; border: 1px solid var(--slate-300); border-radius: var(--radius-lg); }
.changelog-timeline { margin-bottom: 20px; }
.log-entry { display: flex; flex-wrap: wrap; gap: 12px; align-items: baseline; padding: 14px 0; border-bottom: 1px solid var(--slate-300); }
.log-entry:last-child { border-bottom: none; }
.log-version { font-weight: 700; color: var(--primary-dark); min-width: 90px; }
.log-date { color: var(--slate-500); font-size: 0.9rem; min-width: 80px; }
.log-entry p { flex: 1 1 200px; margin: 0; color: var(--slate-700); }
.text-link { color: var(--primary); font-weight: 600; text-decoration: none; }

/* 安全校验 */
.security-verification { padding: 40px; background: var(--slate-100); border-radius: var(--radius-lg); }
.verify-box { background: #fff; padding: 24px; border-radius: var(--radius-sm); border: 1px solid var(--slate-300); font-size: 0.95rem; }
.hash-example { margin-top: 16px; background: var(--slate-800); color: #e2e8f0; padding: 12px; border-radius: 4px; word-break: break-all; font-family: monospace; }
.hash-example code { background: transparent; color: var(--primary); }

/* 下载FAQ */
.download-faq { padding: 40px; background: #fff; border: 1px solid var(--slate-300); border-radius: var(--radius-lg); }
.faq-accordion details { border: 1px solid var(--slate-300); border-radius: var(--radius-sm); margin-bottom: 12px; padding: 0; }
.faq-accordion summary { padding: 16px 20px; font-weight: 600; cursor: pointer; list-style: none; display: flex; justify-content: space-between; color: var(--slate-800); }
.faq-accordion summary::after { content: '▸'; transition: transform 0.2s; }
.faq-accordion details[open] summary::after { transform: rotate(90deg); }
.faq-answer { padding: 0 20px 16px; font-size: 0.95rem; color: var(--slate-600); }

/* 地理规则模块 */
.geodata-integration-module {
    background: var(--slate-100); border: 1px solid #e2e8f0;
    padding: 30px; border-radius: var(--radius-lg);
}
.geodata-integration-module h4 { font-size: 1.25rem; color: var(--slate-900); margin-bottom: 12px; display: flex; align-items: center; gap: 8px; }
.geodata-integration-module h4 svg { width: 22px; height: 22px; fill: var(--primary); }
.geodata-integration-module > p { font-size: 1rem; color: var(--slate-700); margin-bottom: 20px; line-height: 1.7; }
.tech-params-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.param-meta-card { background: #fff; border: 1px solid var(--slate-300); border-radius: var(--radius-sm); padding: 20px; }
.param-meta-card h5 { font-size: 1.05rem; color: var(--slate-800); margin-bottom: 8px; }
.param-meta-card p { font-size: 0.9rem; color: var(--slate-500); margin-bottom: 10px; }
.inline-dl-link { color: var(--primary); font-weight: 600; text-decoration: none; font-size: 0.9rem; }
.inline-dl-link:hover { text-decoration: underline; }

/* 底部（复用首页） */
footer { background: var(--slate-900); color: #94a3b8; padding: 60px 24px 30px; border-top: 4px solid var(--primary); }
.footer-wrapper { max-width: 1100px; margin: 0 auto; }
.footer-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 36px; border-bottom: 1px solid var(--slate-700); padding-bottom: 36px; margin-bottom: 28px; }
.footer-section h5 { color: #fff; font-size: 1rem; margin-bottom: 20px; font-weight: 600; }
.footer-section ul { list-style: none; }
.footer-section ul li { margin-bottom: 12px; }
.footer-section ul li a { color: #94a3b8; text-decoration: none; font-size: 0.9rem; transition: color var(--transition); }
.footer-section ul li a:hover { color: var(--primary); }
.footer-legal { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 16px; font-size: 0.85rem; color: #64748b; }

/* 响应式 */
@media (max-width: 992px) {
    .desktop-premium-row, .mobile-split-row, .tech-params-grid { grid-template-columns: 1fr; }
    .standalone-core-belt { flex-direction: column; align-items: flex-start; }
    .core-actions-cluster { width: 100%; flex-direction: column; }
    .belt-action-btn { text-align: center; }
    .footer-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
    .header-box { flex-direction: column; gap: 16px; }
    nav { justify-content: center; gap: 20px; }
    .footer-grid { grid-template-columns: 1fr; }
    .dl-hero-panel h1 { font-size: 1.8rem; }
    .log-entry { flex-direction: column; gap: 4px; }
}