/* Design tokens */
:root{
  --color-brand:#2E71FF; /* 主色 */
  --color-accent:#EA584A; /* 副色 */
  --color-text:#0f172a;
  --color-muted:#475569;
  --color-bg:#ffffff;
  --color-surface:#f8fafc;
  --radius:14px;
  --shadow:0 10px 30px rgba(0,0,0,0.08);
}
@media (prefers-color-scheme: dark){
  :root{
    --color-text:#e5e7eb;
    --color-muted:#94a3b8;
    --color-bg:#0b1220;
    --color-surface:#0f172a;
    --shadow:0 10px 30px rgba(0,0,0,0.4);
  }
}

/* Base */
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Noto Sans, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  color:var(--color-text);
  background:var(--color-bg);
  line-height:1.6;
  text-rendering:optimizeLegibility;
}
img{max-width:100%;display:block}
a{color:var(--color-brand);text-decoration:none}
a:hover{text-decoration:underline}

.container{max-width:1100px;margin:0 auto;padding:0 20px}
.section{padding:72px 0}
.section.alt{background:var(--color-surface)}
.section-title{font-size:28px;margin:0 0 24px}

/* Header */
.site-header{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.7);backdrop-filter:saturate(180%) blur(12px);border-bottom:1px solid rgba(0,0,0,.06)}
@media (prefers-color-scheme: dark){
  .site-header{background:rgba(15,23,42,.5);border-bottom-color:rgba(255,255,255,.06)}
}
.header-inner{display:flex;align-items:center;justify-content:space-between;height:64px}
.brand{display:flex;align-items:center;gap:10px;color:inherit;font-weight:700}
.nav-toggle{display:none}
.nav-menu{display:flex;gap:20px;margin:0;padding:0;list-style:none}
.nav-menu a{padding:8px 12px;border-radius:10px}
.nav-menu a.active,.nav-menu a:hover{background:rgba(46,113,255,.1)}
@media (max-width: 760px){
  .nav-toggle{display:inline-flex;align-items:center;gap:6px;padding:8px 12px;border-radius:10px;border:1px solid rgba(0,0,0,.08);background:transparent;color:inherit}
  .nav-menu{position:absolute;right:20px;top:64px;background:var(--color-surface);display:none;flex-direction:column;padding:12px;border-radius:12px;box-shadow:var(--shadow)}
  .nav-menu.open{display:flex}
}

/* Hero */
.hero{padding:80px 0 40px;background:radial-gradient(1200px 600px at 80% -10%, rgba(46,113,255,.25), transparent 60%),
linear-gradient(180deg, rgba(46,113,255,.06), transparent 40%)}
.hero-inner{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:center}
.hero-copy h1{font-size:40px;line-height:1.2;margin:0 0 12px}
.hero-copy p{font-size:18px;color:var(--color-muted);margin:0 0 24px}
.hero-actions{display:flex;gap:12px}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:12px 18px;border-radius:12px;font-weight:600;border:1px solid transparent;transition:transform .05s ease}
.btn:active{transform:translateY(1px)}
.btn-primary{background:var(--color-brand);color:#fff;box-shadow:0 10px 25px rgba(46,113,255,.35)}
.btn-primary:hover{filter:brightness(1.05)}
.btn-secondary{background:transparent;border-color:rgba(46,113,255,.35);color:var(--color-brand)}
.hero-art{position:relative;min-height:320px}
.orb{position:absolute;border-radius:50%;filter:blur(8px);opacity:.8}
.orb-1{width:180px;height:180px;background:var(--color-brand);top:20px;right:20px}
.orb-2{width:120px;height:120px;background:var(--color-accent);bottom:10px;left:10px}
.grid-art{position:absolute;inset:40px;border-radius:16px;background:linear-gradient(135deg, rgba(255,255,255,.15), rgba(255,255,255,.02));border:1px solid rgba(0,0,0,.06)}
@media (prefers-color-scheme: dark){
  .grid-art{border-color:rgba(255,255,255,.08)}
}
@media (max-width: 900px){
  .hero-inner{grid-template-columns:1fr;}
  .hero-art{order:-1}
}

/* Cards */
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.card{background:var(--color-surface);padding:20px;border-radius:var(--radius);box-shadow:var(--shadow);border:1px solid rgba(0,0,0,.05)}
.card h3{margin:0 0 8px}
.card p{margin:0;color:var(--color-muted)}
@media (max-width: 900px){
  .cards{grid-template-columns:1fr}
}

/* Features list */
.feature-list{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;list-style:none;margin:0;padding:0}
.feature-list li{background:var(--color-bg);border:1px solid rgba(0,0,0,.06);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.feature-list h3{margin:0 0 8px}
.feature-list p{margin:0;color:var(--color-muted)}
@media (max-width: 900px){
  .feature-list{grid-template-columns:1fr}
}

/* About */
.grid-2{display:grid;grid-template-columns:1.2fr .8fr;gap:20px}
.about-card{background:var(--color-surface);border:1px solid rgba(0,0,0,.06);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.about-card dl{display:grid;grid-template-columns:100px 1fr;gap:8px 12px;margin:0}
.about-card dt{color:var(--color-muted)}
@media (max-width: 900px){
  .grid-2{grid-template-columns:1fr}
}

/* Footer */
.site-footer{border-top:1px solid rgba(0,0,0,.08);padding:24px 0;background:var(--color-surface)}
.footer-inner{display:flex;align-items:center;justify-content:space-between;gap:16px}
.footer-brand{display:flex;align-items:center;gap:8px;font-weight:600}
.footer-meta{display:flex;align-items:center;gap:12px;color:var(--color-muted)}

/* Accessibility */
.skip-link{position:absolute;left:-999px;top:auto;width:1px;height:1px;overflow:hidden}
.skip-link:focus{left:16px;top:16px;width:auto;height:auto;background:#000;color:#fff;padding:8px 12px;border-radius:8px}