/* Learning OS 官网 · 靛蓝 + 暖纸白 + 玻璃质感（与产品端设计语言一致） */
:root{color-scheme:light;
  --paper:#faf7f2; --ink:#232a35; --muted:#6e7681;
  --indigo:#3a5ba0; --indigo-deep:#2e4a85; --indigo-soft:#eef2fa;
  --amber:#e8a13d; --hairline:rgba(35,42,53,.1);
  --glass:rgba(255,255,255,.62); --glass-line:rgba(255,255,255,.7);
  --shadow:0 10px 40px rgba(58,91,160,.1),0 2px 8px rgba(35,42,53,.04)}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);
  font:16px/1.75 system-ui,-apple-system,"Segoe UI","Microsoft YaHei",sans-serif;
  -webkit-font-smoothing:antialiased;overflow-x:hidden}

/* 背景光斑：靛蓝族 + 暖琥珀，极淡 */
.blooms{position:fixed;inset:0;z-index:-1;pointer-events:none;filter:blur(90px);opacity:.55}
.blooms i{position:absolute;border-radius:50%}
.b1{width:520px;height:520px;left:-140px;top:-120px;background:#3a5ba0;opacity:.16}
.b2{width:420px;height:420px;right:-100px;top:16%;background:#7d95c8;opacity:.2}
.b3{width:460px;height:460px;left:24%;bottom:-180px;background:#e8a13d;opacity:.12}

/* 顶栏：吸顶玻璃 */
header{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;
  max-width:1080px;margin:0 auto;padding:14px 28px;
  background:rgba(250,247,242,.72);backdrop-filter:blur(14px) saturate(1.5);
  -webkit-backdrop-filter:blur(14px) saturate(1.5);border-bottom:1px solid var(--hairline)}
.brand{display:flex;align-items:center;gap:10px;color:var(--indigo);text-decoration:none}
.brand .mark{width:26px;height:25px}
.brand-name{font:600 19px/1 system-ui;letter-spacing:-.01em;color:var(--ink)}
header nav{display:flex;gap:26px}
header nav a{color:var(--muted);text-decoration:none;font-size:15px;transition:color .2s}
header nav a:hover{color:var(--indigo)}

main{max-width:1080px;margin:0 auto;padding:0 28px}

/* Hero */
.hero{padding:96px 0 30px}
.eyebrow{color:var(--indigo);letter-spacing:.2em;font-size:14px;font-weight:600;margin:0}
h1{font-family:Georgia,"Times New Roman",serif;
  font-size:clamp(44px,7.5vw,80px);line-height:1.12;letter-spacing:-.03em;
  margin:22px 0 24px}
h1 br{display:none}
.intro{max-width:660px;font-size:19px;color:var(--muted);margin:0 0 36px}
.cta{display:flex;gap:14px;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:9px;padding:13px 26px;border-radius:14px;
  font-size:16px;font-weight:600;text-decoration:none;transition:transform .15s,box-shadow .2s,background .2s}
.btn svg{width:15px;height:15px}
.btn.primary{background:var(--indigo);color:#fff;
  box-shadow:0 8px 24px rgba(58,91,160,.3)}
.btn.primary:hover{background:var(--indigo-deep);transform:translateY(-1px);box-shadow:0 10px 28px rgba(58,91,160,.36)}
.btn.ghost{color:var(--ink);background:var(--glass);border:1px solid var(--glass-line);
  backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px)}
.btn.ghost:hover{background:rgba(255,255,255,.85)}

/* 功能三卡：玻璃卡 */
.features{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;margin:72px 0}
.features article{padding:30px 28px;border-radius:22px;
  background:var(--glass);border:1px solid var(--glass-line);
  backdrop-filter:blur(14px) saturate(1.4);-webkit-backdrop-filter:blur(14px) saturate(1.4);
  box-shadow:var(--shadow);transition:transform .2s,box-shadow .25s}
.features article:hover{transform:translateY(-3px);box-shadow:0 16px 48px rgba(58,91,160,.14),0 3px 10px rgba(35,42,53,.05)}
.ico{display:grid;place-items:center;width:46px;height:46px;border-radius:14px;margin-bottom:18px;
  background:var(--indigo-soft);color:var(--indigo)}
.ico svg{width:24px;height:24px}
h2{font-size:22px;letter-spacing:-.01em;margin:0 0 10px}
.features p{margin:0;color:var(--muted);font-size:15.5px}

/* 下载区：玻璃面板 */
#download{margin:80px 0 90px;padding:40px;border-radius:26px;
  background:linear-gradient(135deg,rgba(238,242,250,.8),rgba(255,255,255,.55));
  border:1px solid var(--glass-line);
  backdrop-filter:blur(14px) saturate(1.4);-webkit-backdrop-filter:blur(14px) saturate(1.4);
  box-shadow:var(--shadow)}
.panel-head h2{font-size:26px}
.panel-sub{color:var(--muted);margin:6px 0 26px}
.ver{color:var(--indigo);font-weight:600}
.downloads{display:flex;flex-wrap:wrap;gap:14px}
.download{display:inline-flex;align-items:center;gap:14px;padding:14px 22px;border-radius:14px;
  background:var(--indigo);color:#fff;text-decoration:none;
  box-shadow:0 8px 24px rgba(58,91,160,.3);transition:background .2s,transform .15s}
.download:hover{background:var(--indigo-deep);transform:translateY(-1px)}
.download svg{width:15px;height:15px}
.dl-platform{font-weight:700;font-size:15px}
.dl-meta{display:flex;flex-direction:column;line-height:1.35;font-size:13.5px;opacity:.92}
.dl-meta small{opacity:.8}
/* 占位态（无 release 时） */
.dl-empty{display:flex;gap:14px;flex-wrap:wrap}
.dl-item{display:flex;flex-direction:column;gap:2px;padding:14px 22px;border-radius:14px;min-width:190px}
.dl-item .dl-platform{font-weight:700}
.dl-item .dl-meta b{font-size:14px}
.dl-item .dl-meta small{color:var(--muted)}
.dl-item.soon{background:rgba(255,255,255,.8);border:1.5px dashed rgba(58,91,160,.45)}
.dl-item.plan{background:rgba(255,255,255,.45);border:1px solid var(--hairline);color:var(--muted)}
.quiet{font-size:14px;color:var(--muted);margin:18px 0 0}

/* 页脚 */
footer{max-width:1080px;margin:0 auto;padding:26px 28px 40px;
  display:flex;align-items:center;justify-content:space-between;gap:14px;flex-wrap:wrap;
  border-top:1px solid var(--hairline)}
.foot-brand{display:flex;align-items:center;gap:9px;color:var(--ink);font-size:14.5px}
.foot-brand .mark{width:18px;height:17px;color:var(--indigo)}
.foot-meta{display:flex;align-items:center;gap:10px;color:var(--muted);font-size:13.5px}
.foot-meta a{color:var(--muted);text-decoration:none}
.foot-meta a:hover{color:var(--indigo)}
.dot{opacity:.5}

@media(max-width:700px){
  .hero{padding:64px 0 20px}
  h1 br{display:inline}
  .features{grid-template-columns:1fr;margin:52px 0}
  #download{padding:28px 22px}
  footer{flex-direction:column;align-items:flex-start}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{transition:none!important}
  .blooms{filter:blur(80px)}
}