:root{--color-bg: #0f1419;--color-surface: #1a2332;--color-surface2: #243044;--color-text: #e8edf4;--color-muted: #94a3b8;--color-accent: #3b82f6;--color-accent-dim: #1d4ed8;--font-en: "Inter", system-ui, sans-serif;--font-zh: "Noto Sans SC", "Microsoft YaHei", sans-serif;--header-h: 56px}*,*:before,*:after{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--color-bg);color:var(--color-text);font-family:var(--font-en);line-height:1.6;-webkit-font-smoothing:antialiased}html[lang=zh-CN] body{font-family:var(--font-zh)}a{color:var(--color-accent);text-decoration:none}a:hover{text-decoration:underline}img{max-width:100%;height:auto;display:block}.container{width:min(1180px,100% - 2rem);margin-inline:auto}.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5rem;padding:.65rem 1.25rem;border:none;border-radius:6px;font-weight:600;font-size:.9rem;cursor:pointer;transition:background .2s,color .2s}.btn-primary{background:var(--color-accent);color:#fff}.btn-primary:hover{background:var(--color-accent-dim)}.btn-ghost{background:transparent;color:var(--color-text);border:1px solid var(--color-surface2)}.btn-ghost:hover{border-color:var(--color-accent);text-decoration:none}.section-title{font-size:1.75rem;font-weight:700;letter-spacing:-.02em;margin:0 0 1rem}.muted{color:var(--color-muted)}.card-grid{display:grid;gap:1.25rem}@media(min-width:768px){.card-grid.cols-2{grid-template-columns:repeat(2,1fr)}.card-grid.cols-4{grid-template-columns:repeat(4,1fr)}}.back-top{position:fixed;right:1.25rem;bottom:1.25rem;z-index:50;width:44px;height:44px;border-radius:50%;border:1px solid var(--color-surface2);background:var(--color-surface);color:var(--color-text);cursor:pointer;box-shadow:0 8px 24px #00000059}.back-top:hover{border-color:var(--color-accent)}