/* iOS 26 Liquid Glass — 暖屿科技在线技术学习平台 */
:root {
  --bg-0: #f5f5f7;
  --bg-1: #ffffff;
  --ink: #1d1d1f;
  --ink-2: #424247;
  --muted: #86868b;
  --line: rgba(0, 0, 0, 0.08);
  --brand: #ff7a18;
  --brand-2: #ff3b9a;
  --brand-3: #5856d6;
  --accent: #007aff;
  --good: #34c759;
  --warn: #ff9f0a;
  --glass: rgba(255, 255, 255, 0.62);
  --glass-strong: rgba(255, 255, 255, 0.78);
  --glass-line: rgba(255, 255, 255, 0.45);
  --shadow-1: 0 6px 24px rgba(20, 20, 40, 0.08);
  --shadow-2: 0 14px 50px rgba(20, 20, 60, 0.14);
  --radius-1: 16px;
  --radius-2: 22px;
  --radius-3: 28px;
  --radius-pill: 999px;
  --maxw: 1180px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-0: #0b0b0f;
    --bg-1: #15151c;
    --ink: #f5f5f7;
    --ink-2: #d2d2d7;
    --muted: #a1a1a6;
    --line: rgba(255, 255, 255, 0.10);
    --glass: rgba(28, 28, 36, 0.58);
    --glass-strong: rgba(28, 28, 36, 0.82);
    --glass-line: rgba(255, 255, 255, 0.10);
    --shadow-1: 0 6px 24px rgba(0, 0, 0, 0.45);
    --shadow-2: 0 14px 50px rgba(0, 0, 0, 0.55);
  }
}

* { box-sizing: border-box; }
html, body { padding: 0; margin: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1200px 700px at 12% -10%, rgba(255,122,24,0.18), transparent 60%),
    radial-gradient(900px 600px at 90% 10%, rgba(88,86,214,0.18), transparent 55%),
    radial-gradient(1100px 800px at 50% 110%, rgba(0,122,255,0.14), transparent 60%),
    var(--bg-0);
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  line-height: 1.55;
  letter-spacing: 0.01em;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
button { font: inherit; cursor: pointer; }

/* Layout container — 居中自适应 */
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

/* ===== Top Nav ===== */
.nav {
  position: sticky; top: 14px; z-index: 60;
  margin: 14px auto 0; max-width: var(--maxw);
  padding: 10px 18px;
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  background: var(--glass);
  backdrop-filter: blur(28px) saturate(180%);
  -webkit-backdrop-filter: blur(28px) saturate(180%);
  border: 1px solid var(--glass-line);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-1);
}
.nav-brand {
  display: flex; align-items: center; gap: 10px; font-weight: 700; letter-spacing: 0.02em;
}
.nav-brand .logo {
  width: 30px; height: 30px; border-radius: 9px;
  background: conic-gradient(from 220deg, var(--brand), var(--brand-2), var(--brand-3), var(--brand));
  box-shadow: inset 0 0 0 1px rgba(255,255,255,0.35), 0 6px 18px rgba(255,122,24,0.35);
  position: relative;
}
.nav-brand .logo::after {
  content: "暖"; color: #fff; font-weight: 800; font-size: 14px;
  position: absolute; inset: 0; display: grid; place-items: center;
  text-shadow: 0 1px 2px rgba(0,0,0,0.25);
}
.nav-links { display: flex; gap: 4px; }
.nav-links a {
  padding: 8px 14px; border-radius: var(--radius-pill); color: var(--ink-2);
  font-size: 14.5px; transition: background .25s, color .25s;
}
.nav-links a:hover, .nav-links a.active { background: rgba(0,0,0,0.06); color: var(--ink); }
@media (prefers-color-scheme: dark) {
  .nav-links a:hover, .nav-links a.active { background: rgba(255,255,255,0.10); }
}
.nav-cta {
  padding: 9px 18px; border-radius: var(--radius-pill);
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  color: #fff; font-weight: 600; font-size: 14px; box-shadow: 0 8px 22px rgba(255,59,154,0.32);
  border: none;
}
.nav-burger { display: none; background: none; border: none; padding: 6px; }
.nav-burger span { display: block; width: 22px; height: 2px; margin: 5px 0; background: var(--ink); border-radius: 2px; }

@media (max-width: 760px) {
  .nav { padding: 8px 12px; }
  .nav-links { display: none; position: absolute; top: 60px; right: 12px; left: 12px;
    background: var(--glass-strong); backdrop-filter: blur(24px); border: 1px solid var(--glass-line);
    border-radius: var(--radius-2); padding: 10px; flex-direction: column; gap: 0; box-shadow: var(--shadow-2); }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 14px; }
  .nav-cta { display: none; }
  .nav-burger { display: block; }
}

/* ===== Hero ===== */
.hero { padding: 64px 0 40px; }
.hero-grid { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 38px; align-items: center; }
@media (max-width: 880px) { .hero-grid { grid-template-columns: 1fr; gap: 28px; } }

.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 14px; border-radius: var(--radius-pill);
  background: var(--glass); border: 1px solid var(--glass-line);
  backdrop-filter: blur(18px); -webkit-backdrop-filter: blur(18px);
  font-size: 13px; color: var(--ink-2); margin-bottom: 18px;
}
.eyebrow .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--good); box-shadow: 0 0 10px rgba(52,199,89,0.7); }

h1.h-display {
  font-size: clamp(34px, 5.4vw, 60px);
  line-height: 1.08; letter-spacing: -0.02em; font-weight: 800; margin: 0 0 18px;
  background: linear-gradient(120deg, var(--ink) 35%, var(--brand) 60%, var(--brand-3) 100%);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.h-sub { color: var(--ink-2); font-size: clamp(15px, 1.6vw, 18px); max-width: 540px; margin: 0 0 26px; }
.cta-row { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  padding: 12px 22px; border-radius: var(--radius-pill); font-weight: 600; font-size: 15px;
  border: 1px solid transparent; transition: transform .15s, box-shadow .25s;
}
.btn:active { transform: translateY(1px); }
.btn-primary {
  color: #fff; background: linear-gradient(135deg, var(--brand), var(--brand-2));
  box-shadow: 0 12px 28px rgba(255,59,154,0.32);
}
.btn-primary:hover { box-shadow: 0 16px 36px rgba(255,59,154,0.42); }
.btn-ghost {
  background: var(--glass); color: var(--ink); border: 1px solid var(--glass-line);
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
}

.hero-stats { display: flex; gap: 24px; margin-top: 28px; flex-wrap: wrap; }
.hero-stats .s { background: var(--glass); border: 1px solid var(--glass-line); padding: 12px 16px; border-radius: var(--radius-1); backdrop-filter: blur(18px); }
.hero-stats .s b { font-size: 20px; display: block; }
.hero-stats .s span { color: var(--muted); font-size: 12.5px; }

/* Hero visual — liquid glass stack */
.hero-visual {
  position: relative; aspect-ratio: 4/3; border-radius: var(--radius-3); overflow: hidden;
  box-shadow: var(--shadow-2); border: 1px solid var(--glass-line);
  background: linear-gradient(135deg, rgba(255,122,24,0.18), rgba(88,86,214,0.18));
}
.hero-visual img { width: 100%; height: 100%; object-fit: cover; }
.hero-card-float {
  position: absolute; left: 14px; bottom: 14px; right: 14px;
  background: var(--glass-strong); backdrop-filter: blur(28px); border: 1px solid var(--glass-line);
  border-radius: var(--radius-2); padding: 14px 16px;
  display: flex; align-items: center; gap: 12px;
}
.hero-card-float .ring {
  width: 42px; height: 42px; border-radius: 12px;
  background: conic-gradient(from 90deg, var(--brand), var(--brand-3), var(--brand));
  display: grid; place-items: center; color: #fff; font-weight: 800;
}
.hero-card-float small { color: var(--muted); display: block; font-size: 12px; }

/* ===== Section common ===== */
.section { padding: 56px 0; }
.section-head { text-align: center; max-width: 720px; margin: 0 auto 36px; }
.section-head h2 { font-size: clamp(26px, 3.4vw, 38px); margin: 0 0 10px; letter-spacing: -0.02em; }
.section-head p { color: var(--ink-2); margin: 0; }

/* Course grid */
.cards {
  display: grid; gap: 20px;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
}
.card {
  background: var(--glass-strong); backdrop-filter: blur(24px) saturate(170%);
  -webkit-backdrop-filter: blur(24px) saturate(170%);
  border: 1px solid var(--glass-line);
  border-radius: var(--radius-3); overflow: hidden;
  box-shadow: var(--shadow-1);
  transition: transform .35s cubic-bezier(.2,.8,.2,1), box-shadow .35s;
  display: flex; flex-direction: column;
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-2); }
.card .cover { aspect-ratio: 16/10; overflow: hidden; position: relative; }
.card .cover img { width: 100%; height: 100%; object-fit: cover; transition: transform .8s; }
.card:hover .cover img { transform: scale(1.04); }
.card .tag {
  position: absolute; top: 12px; left: 12px; padding: 6px 10px; border-radius: var(--radius-pill);
  background: var(--glass-strong); backdrop-filter: blur(18px); font-size: 12px; color: var(--ink);
  border: 1px solid var(--glass-line);
}
.card .body { padding: 18px 18px 20px; display: flex; flex-direction: column; gap: 10px; flex: 1; }
.card h3 { margin: 0; font-size: 18px; letter-spacing: -0.01em; }
.card .desc { color: var(--ink-2); font-size: 14px; min-height: 42px; }
.card .meta { display: flex; align-items: center; justify-content: space-between; margin-top: auto; padding-top: 8px; }
.card .price { font-weight: 700; font-size: 20px; color: var(--brand); }
.card .price .o { font-size: 12px; color: var(--muted); text-decoration: line-through; margin-left: 6px; font-weight: 500; }
.card .stars { color: #ffb000; font-size: 13px; }
.card .stars .num { color: var(--muted); margin-left: 4px; }

/* Features */
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 18px; }
.feat {
  background: var(--glass); border: 1px solid var(--glass-line); padding: 22px;
  border-radius: var(--radius-2); backdrop-filter: blur(20px);
}
.feat .ico {
  width: 44px; height: 44px; border-radius: 14px; display: grid; place-items: center;
  background: linear-gradient(135deg, var(--brand), var(--brand-2)); color: #fff; font-weight: 800; margin-bottom: 12px;
  box-shadow: 0 8px 22px rgba(255,59,154,0.25);
}
.feat h4 { margin: 0 0 6px; font-size: 17px; }
.feat p { margin: 0; color: var(--ink-2); font-size: 14px; }

/* Teachers */
.teachers { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 18px; }
.teacher {
  background: var(--glass-strong); border: 1px solid var(--glass-line); border-radius: var(--radius-2);
  padding: 22px; text-align: center; backdrop-filter: blur(20px);
}
.teacher img { width: 96px; height: 96px; border-radius: 50%; object-fit: cover; margin: 0 auto 12px; box-shadow: var(--shadow-1); }
.teacher h4 { margin: 0 0 4px; }
.teacher .role { color: var(--brand); font-size: 13px; }
.teacher p { color: var(--ink-2); font-size: 13.5px; margin: 10px 0 0; }

/* Reviews */
.reviews { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 18px; }
.review {
  background: var(--glass); border: 1px solid var(--glass-line); border-radius: var(--radius-2);
  padding: 20px; backdrop-filter: blur(20px);
}
.review header { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
.review .avatar { width: 40px; height: 40px; border-radius: 50%; background: linear-gradient(135deg, var(--brand-3), var(--accent)); color: #fff; display: grid; place-items: center; font-weight: 700; }
.review .who b { display: block; }
.review .who small { color: var(--muted); }
.review .stars { color: #ffb000; }
.review p { color: var(--ink-2); margin: 6px 0 0; font-size: 14.5px; }

/* Detail page */
.detail-grid { display: grid; grid-template-columns: 1.4fr 0.9fr; gap: 32px; }
@media (max-width: 880px) { .detail-grid { grid-template-columns: 1fr; } }
.detail-cover { border-radius: var(--radius-3); overflow: hidden; box-shadow: var(--shadow-2); aspect-ratio: 16/9; background: var(--bg-1); }
.detail-cover img { width: 100%; height: 100%; object-fit: cover; }
.detail-side {
  position: sticky; top: 110px;
  background: var(--glass-strong); border: 1px solid var(--glass-line);
  border-radius: var(--radius-3); padding: 24px; backdrop-filter: blur(28px);
  box-shadow: var(--shadow-1); align-self: start;
}
.detail-side .price { font-size: 30px; font-weight: 800; color: var(--brand); }
.detail-side .price .o { font-size: 14px; color: var(--muted); text-decoration: line-through; margin-left: 8px; font-weight: 500; }
.detail-side .meta { color: var(--ink-2); font-size: 14px; margin-top: 6px; }
.detail-side .buy { display: block; width: 100%; margin-top: 18px; text-align: center; }
.detail-side ul { list-style: none; padding: 0; margin: 18px 0 0; font-size: 14px; color: var(--ink-2); display: grid; gap: 8px; }
.detail-side ul li::before { content: "✓ "; color: var(--good); font-weight: 700; }

.detail h1 { font-size: clamp(24px, 3vw, 34px); margin: 18px 0 8px; letter-spacing: -0.02em; }
.detail .tags { display: flex; gap: 8px; flex-wrap: wrap; }
.detail .tags span { padding: 4px 10px; border-radius: var(--radius-pill); background: rgba(0,122,255,0.10); color: var(--accent); font-size: 12.5px; }
.detail h3 { margin: 28px 0 10px; font-size: 18px; letter-spacing: -0.01em; }
.detail p { color: var(--ink-2); }

.outline { background: var(--glass); border: 1px solid var(--glass-line); border-radius: var(--radius-2); padding: 18px 22px; backdrop-filter: blur(18px); }
.outline ol { padding-left: 18px; margin: 0; color: var(--ink-2); display: grid; gap: 8px; }

/* Order page */
.order-grid { display: grid; grid-template-columns: 1.2fr 0.8fr; gap: 28px; align-items: start; }
@media (max-width: 880px) { .order-grid { grid-template-columns: 1fr; } }
.panel {
  background: var(--glass-strong); border: 1px solid var(--glass-line); border-radius: var(--radius-3);
  padding: 26px; backdrop-filter: blur(28px) saturate(170%); box-shadow: var(--shadow-1);
}
.panel h3 { margin: 0 0 16px; }
.field { display: grid; gap: 6px; margin-bottom: 14px; }
.field label { font-size: 13px; color: var(--ink-2); }
.field input, .field textarea, .field select {
  width: 100%; padding: 12px 14px; border-radius: 14px; border: 1px solid var(--line);
  background: var(--bg-1); color: var(--ink); font: inherit;
  transition: border-color .2s, box-shadow .2s;
}
.field input:focus, .field textarea:focus, .field select:focus {
  outline: none; border-color: var(--accent); box-shadow: 0 0 0 4px rgba(0,122,255,0.18);
}
.row-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 520px) { .row-2 { grid-template-columns: 1fr; } }

.order-summary { display: flex; gap: 14px; align-items: center; }
.order-summary img { width: 96px; height: 70px; object-fit: cover; border-radius: 14px; }
.order-summary .info { flex: 1; }
.order-summary h4 { margin: 0 0 4px; }
.order-summary .price { color: var(--brand); font-weight: 700; }
.totals { margin-top: 18px; padding-top: 16px; border-top: 1px dashed var(--line); display: grid; gap: 8px; font-size: 14px; }
.totals .line { display: flex; justify-content: space-between; }
.totals .grand { font-size: 18px; font-weight: 800; color: var(--brand); }
.qty { display: inline-flex; align-items: center; border: 1px solid var(--line); border-radius: var(--radius-pill); overflow: hidden; }
.qty button { width: 34px; height: 34px; border: none; background: transparent; color: var(--ink); font-size: 18px; }
.qty input { width: 44px; text-align: center; border: none; background: transparent; color: var(--ink); font-size: 15px; }

.pay-options { display: grid; grid-template-columns: repeat(auto-fit, minmax(140px,1fr)); gap: 10px; margin-top: 8px; }
.pay { display: flex; align-items: center; gap: 10px; padding: 12px 14px; border-radius: 14px; border: 1px solid var(--line); cursor: pointer; background: var(--bg-1); }
.pay input { accent-color: var(--brand); }
.pay .icn { width: 26px; height: 26px; border-radius: 7px; display: grid; place-items: center; color: #fff; font-weight: 700; font-size: 12px; }
.pay.alipay .icn { background: #1677ff; }
.pay.wxpay .icn { background: #07c160; }
.pay.bank .icn { background: linear-gradient(135deg,#5856d6,#007aff); }

/* About page */
.values { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 18px; margin-top: 24px; }
.timeline { display: grid; gap: 16px; margin-top: 24px; }
.timeline .it { background: var(--glass); border: 1px solid var(--glass-line); padding: 18px 22px; border-radius: var(--radius-2); backdrop-filter: blur(20px); }
.timeline .yr { color: var(--brand); font-weight: 800; font-size: 14px; letter-spacing: 0.04em; }

/* Contact page */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
@media (max-width: 760px) { .contact-grid { grid-template-columns: 1fr; } }
.kv { display: flex; gap: 12px; padding: 14px 0; border-bottom: 1px dashed var(--line); }
.kv:last-child { border-bottom: 0; }
.kv .k { width: 84px; color: var(--muted); font-size: 14px; }
.kv .v { color: var(--ink); font-size: 14.5px; }

/* Footer */
.footer {
  margin-top: 64px; padding: 36px 0 28px;
  background: var(--glass); border-top: 1px solid var(--line);
  backdrop-filter: blur(24px);
}
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 26px; }
@media (max-width: 760px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
.footer h5 { margin: 0 0 12px; font-size: 14px; letter-spacing: 0.04em; color: var(--muted); text-transform: uppercase; }
.footer ul { list-style: none; padding: 0; margin: 0; display: grid; gap: 8px; }
.footer a { color: var(--ink-2); font-size: 14px; }
.footer a:hover { color: var(--brand); }
.foot-bar {
  margin-top: 26px; padding-top: 18px; border-top: 1px solid var(--line);
  display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap;
  color: var(--muted); font-size: 13px;
}
.foot-bar a { color: var(--muted); }
.foot-bar a:hover { color: var(--brand); }

/* Floating widgets */
.fab {
  position: fixed; right: 22px; z-index: 80;
  width: 52px; height: 52px; border-radius: 50%;
  border: 1px solid var(--glass-line);
  background: var(--glass-strong); backdrop-filter: blur(24px);
  box-shadow: var(--shadow-2);
  display: grid; place-items: center; color: var(--ink);
  transition: transform .25s, opacity .25s;
}
.fab:hover { transform: translateY(-2px); }
.fab.back-top {
  bottom: 22px;
  opacity: 0; pointer-events: none;
}
.fab.back-top.visible { opacity: 1; pointer-events: auto; }
.fab.chat {
  /* 错开返回顶部 80px，避免重叠 */
  bottom: calc(22px + 52px + 14px);
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
  color: #fff; border: none;
  box-shadow: 0 16px 36px rgba(255,59,154,0.42);
}
.fab.chat .pulse {
  position: absolute; inset: -4px; border-radius: 50%;
  border: 2px solid rgba(255,122,24,0.55); animation: pulse 1.8s ease-out infinite;
}
@keyframes pulse {
  0% { transform: scale(0.85); opacity: 0.9; }
  100% { transform: scale(1.5); opacity: 0; }
}

/* Chat panel */
.chat-panel {
  position: fixed; right: 22px; bottom: calc(22px + 52px + 14px + 52px + 14px);
  width: min(340px, calc(100vw - 44px)); max-height: 70vh;
  background: var(--glass-strong); backdrop-filter: blur(28px) saturate(180%);
  border: 1px solid var(--glass-line); border-radius: var(--radius-3);
  box-shadow: var(--shadow-2); z-index: 81;
  transform: translateY(20px) scale(0.96); opacity: 0; pointer-events: none;
  transition: transform .25s cubic-bezier(.2,.9,.2,1), opacity .25s;
  display: flex; flex-direction: column; overflow: hidden;
}
.chat-panel.open { transform: translateY(0) scale(1); opacity: 1; pointer-events: auto; }
.chat-head {
  padding: 14px 16px; display: flex; align-items: center; gap: 10px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(135deg, rgba(255,122,24,0.10), rgba(88,86,214,0.10));
}
.chat-head .ava { width: 34px; height: 34px; border-radius: 10px; background: linear-gradient(135deg, var(--brand), var(--brand-3)); color: #fff; display: grid; place-items: center; font-weight: 800; }
.chat-head h5 { margin: 0; font-size: 14px; }
.chat-head small { color: var(--good); font-size: 11.5px; }
.chat-body { flex: 1; overflow-y: auto; padding: 14px 14px 6px; display: flex; flex-direction: column; gap: 10px; }
.msg { max-width: 85%; padding: 10px 13px; border-radius: 16px; font-size: 14px; line-height: 1.45; }
.msg.bot { background: var(--bg-1); border: 1px solid var(--line); color: var(--ink); align-self: flex-start; border-top-left-radius: 6px; }
.msg.me { background: linear-gradient(135deg, var(--brand), var(--brand-2)); color: #fff; align-self: flex-end; border-top-right-radius: 6px; }
.chat-input {
  display: flex; gap: 8px; padding: 10px; border-top: 1px solid var(--line);
}
.chat-input input { flex: 1; padding: 10px 12px; border-radius: 12px; border: 1px solid var(--line); background: var(--bg-1); color: var(--ink); font: inherit; outline: none; }
.chat-input button { padding: 10px 14px; border-radius: 12px; border: none; background: linear-gradient(135deg, var(--brand), var(--brand-2)); color: #fff; font-weight: 600; }

/* Toast */
.toast {
  position: fixed; left: 50%; bottom: 36px; transform: translateX(-50%) translateY(40px);
  background: var(--ink); color: var(--bg-0); padding: 12px 18px; border-radius: var(--radius-pill);
  font-size: 14px; opacity: 0; transition: opacity .25s, transform .25s; z-index: 100;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* Utility */
.center { text-align: center; }
.mt-32 { margin-top: 32px; }
.divider { height: 1px; background: var(--line); margin: 32px 0; }