:root {
  --bg: #f6f7fb;
  --surface: #ffffff;
  --border: #e4e7ee;
  --text: #1a1d26;
  --text-dim: #6b7280;
  --primary: #4f46e5;
  --primary-hover: #4338ca;
  --primary-soft: #eef2ff;
  --success: #059669;
  --success-soft: #ecfdf5;
  --warn: #d97706;
  --danger: #dc2626;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(0,0,0,.06), 0 8px 24px rgba(0,0,0,.05);
  --shadow-lg: 0 4px 12px rgba(0,0,0,.08), 0 20px 48px rgba(0,0,0,.08);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary); text-decoration: none; }
a:hover { text-decoration: underline; }

button { font-family: inherit; cursor: pointer; border: none; background: none; }
input, select, textarea { font-family: inherit; font-size: 15px; }

/* ---------- 布局 ---------- */
.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }
.row { display: flex; gap: 16px; }
.col { flex: 1; }

/* ---------- 顶栏 ---------- */
.header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,.92);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; gap: 24px; height: 64px; }
.logo { display: flex; align-items: center; gap: 8px; font-size: 18px; font-weight: 700; color: var(--text); text-decoration: none; }
.logo:hover { text-decoration: none; }
.logo-icon { font-size: 22px; }
.nav { display: flex; gap: 4px; margin-left: 8px; }
.nav a {
  padding: 7px 14px; border-radius: 8px; color: var(--text-dim);
  font-size: 14.5px; font-weight: 500; text-decoration: none; transition: .15s;
}
.nav a:hover { background: var(--bg); color: var(--text); text-decoration: none; }
.nav a.active { background: var(--primary-soft); color: var(--primary); }
.header-right { margin-left: auto; display: flex; align-items: center; gap: 12px; }

.avatar {
  width: 32px; height: 32px; border-radius: 50%;
  background: linear-gradient(135deg, #6366f1, #a855f7);
  color: #fff; display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 600; flex-shrink: 0;
}
.user-chip { display: flex; align-items: center; gap: 8px; font-size: 14px; color: var(--text-dim); }
.user-chip b { color: var(--text); font-weight: 600; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  padding: 9px 18px; border-radius: 9px; font-size: 14.5px; font-weight: 600;
  transition: .15s; white-space: nowrap; border: 1px solid transparent;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover:not(:disabled) { background: var(--primary-hover); }
.btn-ghost { background: transparent; color: var(--text-dim); border-color: var(--border); }
.btn-ghost:hover:not(:disabled) { background: var(--bg); color: var(--text); }
.btn-soft { background: var(--primary-soft); color: var(--primary); }
.btn-soft:hover:not(:disabled) { background: #e0e7ff; }
.btn-success { background: var(--success); color: #fff; }
/* 课程卡片上的生成者署名（AI 课程是全站共享的） */
.byline { font-size:12.5px; color:var(--text-dim); margin:-6px 0 12px; }

/* AI 工作台的额度提示条 */
.quota-bar { display:flex; align-items:center; gap:10px; flex-wrap:wrap; font-size:13.5px;
  background:var(--surface-2, #f4f5fa); border:1px solid var(--border); border-radius:10px;
  padding:11px 14px; margin-top:16px; }
.quota-bar.ok { border-color:rgba(16,185,129,.4); background:rgba(16,185,129,.08); }
.quota-bar.warn { border-color:rgba(245,158,11,.45); background:rgba(245,158,11,.09); }
.quota-bar .btn { margin-left:auto; }
.quota-bar .btn + .btn { margin-left:0; }
/* 付费墙与会员 */
.tag-price { background:rgba(99,102,241,.12); border-color:var(--primary); color:var(--primary); }

/* 首页搜索框：做成页面上最显眼的一个控件（之前太素，用户压根没注意到） */
.hero-search-wrap { max-width:660px; margin:26px 0 16px; }
.hero-search {
  display:flex; align-items:stretch;
  background:var(--card);
  border:2px solid var(--primary);
  border-radius:14px;
  padding:5px 5px 5px 0;
  box-shadow:0 8px 28px rgba(99,102,241,.18);
  transition:box-shadow .15s, border-color .15s;
}
.hero-search:focus-within { box-shadow:0 10px 34px rgba(99,102,241,.30); }
.hero-search .search-ico {
  display:flex; align-items:center; padding:0 8px 0 16px;
  font-size:17px; opacity:.65; pointer-events:none;
}
.hero-search input {
  flex:1; min-width:0; border:0; outline:none; background:transparent;
  font-size:16.5px; color:var(--text); padding:14px 4px; border-radius:10px;
  -webkit-appearance:none; appearance:none;
}
.hero-search input::placeholder { color:var(--text-dim); }
.hero-search input::-webkit-search-cancel-button { -webkit-appearance:none; appearance:none; }
.hero-search .search-clear {
  display:none; border:0; background:transparent; cursor:pointer;
  font-size:20px; line-height:1; color:var(--text-dim); padding:0 10px; border-radius:8px;
}
.hero-search.has-text .search-clear { display:block; }
.hero-search .search-clear:hover { color:var(--text); background:var(--primary-soft); }
.hero-search .search-go { border-radius:10px; padding:0 26px; font-size:15.5px; font-weight:600; }
.search-hints {
  display:flex; flex-wrap:wrap; gap:8px; align-items:center;
  margin-top:12px; font-size:13px; color:var(--text-dim);
}
.search-hints .hint-label { flex:0 0 auto; }
.search-hints button {
  background:transparent; border:1px solid var(--border); border-radius:999px;
  padding:4px 13px; font-size:13px; color:var(--text-dim); cursor:pointer;
  transition:border-color .15s, color .15s;
}
.search-hints button:hover { border-color:var(--primary); color:var(--primary); }

/* 搜索结果里把命中的词标出来 */
mark { background:rgba(250,204,21,.32); color:inherit; padding:0 2px; border-radius:3px; font-weight:600; }
.course-card h3 a { color:inherit; text-decoration:none; }
.course-card h3 a:hover { color:var(--primary); }

@media (max-width:640px) {
  .hero-search { flex-wrap:wrap; padding:5px; border-radius:12px; }
  .hero-search .search-ico { padding-left:10px; }
  .hero-search .search-go { width:100%; margin-top:4px; padding:12px 0; }
}
.quota-bar .btn { margin-left:auto; }

/* 收藏按钮：未收藏是描边，已收藏是实心星 */
.btn-fav { background: transparent; border: 1px solid var(--border); color: var(--text-dim);
  white-space: nowrap; }
.btn-fav:hover { border-color: var(--warning, #f59e0b); color: var(--warning, #f59e0b); }
.btn-fav[data-on="1"] { background: #fffbeb; border-color: #fcd34d; color: #b45309; font-weight: 600; }
.btn-sm { padding: 5px 12px; font-size: 13px; border-radius: 7px; }
.btn-lg { padding: 13px 28px; font-size: 16px; border-radius: 10px; }
.btn-block { width: 100%; }
.btn:disabled { opacity: .55; cursor: not-allowed; }

/* ---------- 卡片 ---------- */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow);
}
.card-hover { transition: .2s; }
.card-hover:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); border-color: #d5d9e6; }

/* ---------- Hero ---------- */
.hero { padding: 72px 0 56px; }
.hero-inner { display: flex; align-items: center; gap: 56px; }
.hero-copy { flex: 1; }
.badge {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 5px 13px; border-radius: 100px; font-size: 13px; font-weight: 600;
  background: var(--primary-soft); color: var(--primary); margin-bottom: 18px;
}
.hero h1 { font-size: 44px; line-height: 1.2; font-weight: 800; letter-spacing: -.5px; margin-bottom: 18px; }
.hero h1 em { font-style: normal; color: var(--primary); }
.hero p { font-size: 17px; color: var(--text-dim); margin-bottom: 28px; max-width: 560px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 36px; margin-top: 40px; }
.hero-stat b { display: block; font-size: 27px; font-weight: 800; letter-spacing: -.5px; }
.hero-stat span { font-size: 13.5px; color: var(--text-dim); }
.hero-visual {
  flex: 1; background: linear-gradient(150deg, #eef2ff, #faf5ff);
  border-radius: 18px; padding: 30px; min-height: 330px;
  display: flex; flex-direction: column; justify-content: center; gap: 14px;
}
.hero-visual .vc {
  background: #fff; border: 1px solid var(--border); border-radius: 11px;
  padding: 14px 18px; box-shadow: var(--shadow);
  font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: 13.5px;
}
.hero-visual .vc .c1 { color: #8250df; }
.hero-visual .vc .c2 { color: #1a1d26; }
.hero-visual .vc .c3 { color: #059669; }
.hero-visual .vc.dim { color: var(--text-dim); }

/* ---------- 区块 ---------- */
.section { padding: 56px 0; }
.section-head { margin-bottom: 32px; }
.section-head h2 { font-size: 27px; font-weight: 700; letter-spacing: -.3px; margin-bottom: 8px; }
.section-head p { color: var(--text-dim); font-size: 15px; }

.grid { display: grid; gap: 20px; }
.grid-3 { grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); }
.grid-2 { grid-template-columns: repeat(auto-fill, minmax(400px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fill, minmax(210px, 1fr)); }

/* ---------- 课程卡 ---------- */
.course-card { display: flex; flex-direction: column; height: 100%; }
.course-cover {
  height: 140px; border-radius: 10px; display: flex; align-items: center;
  justify-content: center; font-size: 46px; margin-bottom: 18px;
  background: linear-gradient(135deg, #eef2ff, #e0e7ff);
}
.course-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 7px; line-height: 1.4; }
.course-card .sub { font-size: 14px; color: var(--text-dim); margin-bottom: 16px; flex: 1; }
.course-meta { display: flex; gap: 14px; flex-wrap: wrap; font-size: 13px; color: var(--text-dim); margin-bottom: 16px; }
.course-meta span { display: inline-flex; align-items: center; gap: 4px; }
.tag {
  display: inline-block; padding: 3px 10px; border-radius: 6px;
  font-size: 12.5px; font-weight: 600;
}
.tag-blue { background: var(--primary-soft); color: var(--primary); }
.tag-green { background: var(--success-soft); color: var(--success); }
.tag-gray { background: #f3f4f6; color: var(--text-dim); }
.tag-amber { background: #fffbeb; color: var(--warn); }

/* ---------- 特性 ---------- */
.feature { text-align: center; padding: 28px 20px; }
.feature .ic {
  width: 50px; height: 50px; border-radius: 13px; margin: 0 auto 16px;
  display: flex; align-items: center; justify-content: center; font-size: 24px;
  background: var(--primary-soft);
}
.feature h4 { font-size: 16.5px; font-weight: 700; margin-bottom: 8px; }
.feature p { font-size: 14px; color: var(--text-dim); }

/* ---------- 表单 ---------- */
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 7px; }
.form-group input, .form-group select, .form-group textarea {
  width: 100%; padding: 11px 14px; border: 1px solid var(--border);
  border-radius: 9px; background: #fff; transition: .15s; color: var(--text);
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus {
  outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79,70,229,.1);
}
.form-hint { font-size: 12.5px; color: var(--text-dim); margin-top: 5px; }
.form-error {
  padding: 10px 14px; border-radius: 8px; font-size: 13.5px;
  background: #fef2f2; color: var(--danger); margin-bottom: 16px;
  border: 1px solid #fecaca;
}
.form-success {
  padding: 10px 14px; border-radius: 8px; font-size: 13.5px;
  background: var(--success-soft); color: var(--success); margin-bottom: 16px;
  border: 1px solid #a7f3d0;
}

.auth-wrap { max-width: 420px; margin: 56px auto; }
.auth-tabs { display: flex; gap: 4px; padding: 4px; background: var(--bg); border-radius: 10px; margin-bottom: 24px; }
.auth-tab {
  flex: 1; padding: 9px; border-radius: 7px; font-size: 14.5px; font-weight: 600;
  color: var(--text-dim); transition: .15s;
}
.auth-tab.active { background: #fff; color: var(--text); box-shadow: var(--shadow); }

/* ---------- 课程学习页 ---------- */
.learn-layout { display: grid; grid-template-columns: 270px 1fr; gap: 28px; align-items: start; }

.outline { position: sticky; top: 84px; max-height: calc(100vh - 108px); overflow-y: auto; padding-right: 6px; }
.outline-head { padding: 16px 18px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); margin-bottom: 14px; }
.outline-head h3 { font-size: 15.5px; font-weight: 700; line-height: 1.4; margin-bottom: 8px; }
.progress-bar { height: 6px; background: #e9ecf3; border-radius: 100px; overflow: hidden; margin-top: 10px; }
.progress-fill { height: 100%; background: linear-gradient(90deg, #6366f1, #a855f7); border-radius: 100px; transition: width .4s; }

.outline-day { margin-bottom: 10px; }
.outline-day-label {
  font-size: 12px; font-weight: 700; color: var(--text-dim); text-transform: uppercase;
  letter-spacing: .4px; padding: 0 8px 6px;
}
.outline-item {
  display: flex; align-items: flex-start; gap: 9px; padding: 8px 10px;
  border-radius: 8px; font-size: 13.8px; color: var(--text-dim);
  transition: .13s; text-decoration: none; margin-bottom: 1px;
}
.outline-item:hover { background: #eef0f6; color: var(--text); text-decoration: none; }
.outline-item.active { background: var(--primary-soft); color: var(--primary); font-weight: 600; }
.outline-item .dot {
  width: 18px; height: 18px; border-radius: 50%; flex-shrink: 0; margin-top: 1px;
  border: 1.5px solid var(--border); display: flex; align-items: center;
  justify-content: center; font-size: 11px; color: #fff;
}
.outline-item.done .dot { background: var(--success); border-color: var(--success); }
.outline-item.active .dot { border-color: var(--primary); }

/* ---------- 课时正文 ---------- */
.lesson-content { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 36px 44px; box-shadow: var(--shadow); }
.lesson-header { border-bottom: 1px solid var(--border); padding-bottom: 20px; margin-bottom: 28px; }
.lesson-header h1 { font-size: 27px; font-weight: 700; letter-spacing: -.4px; margin-bottom: 10px; }
.lesson-meta { display: flex; gap: 12px; flex-wrap: wrap; font-size: 13.5px; color: var(--text-dim); }

.prose { font-size: 16px; line-height: 1.85; }
.prose h2 {
  font-size: 22px; font-weight: 700; margin: 36px 0 14px;
  padding-bottom: 9px; border-bottom: 1px solid var(--border); letter-spacing: -.2px;
}
.prose h2:first-child { margin-top: 0; }
.prose h3 { font-size: 18.5px; font-weight: 700; margin: 28px 0 11px; }
.prose p { margin-bottom: 15px; }
.prose ul, .prose ol { margin: 0 0 16px 26px; }
.prose li { margin-bottom: 6px; }
.prose code {
  background: #f3f4f6; padding: 2px 7px; border-radius: 5px;
  font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: .88em; color: #be185d;
}
.prose pre {
  background: #1e2030; color: #e4e7ee; padding: 18px 20px;
  border-radius: 10px; overflow-x: auto; margin-bottom: 18px; font-size: 13.5px; line-height: 1.65;
}
.prose pre code { background: none; color: inherit; padding: 0; font-size: inherit; }
.prose blockquote {
  border-left: 3px solid var(--primary); background: var(--primary-soft);
  padding: 13px 18px; border-radius: 0 8px 8px 0; margin-bottom: 18px; color: var(--text);
}
.prose blockquote p { margin: 0; }
.prose blockquote strong { color: var(--primary); }
.prose table { width: 100%; border-collapse: collapse; margin-bottom: 20px; font-size: 14.5px; }
.prose th, .prose td { padding: 10px 13px; border: 1px solid var(--border); text-align: left; }
.prose th { background: #fafbfd; font-weight: 700; }
.prose strong { font-weight: 700; }
.prose hr { border: none; border-top: 1px solid var(--border); margin: 30px 0; }

/* 警告块 */
.prose .warn, .prose .warning {
  background: #fffbeb; border: 1px solid #fde68a; border-left: 3px solid var(--warn);
  padding: 13px 18px; border-radius: 0 8px 8px 0; margin-bottom: 18px;
}
.prose .warn p, .prose .warning p { margin: 0; }

/* ---------- 沙箱 ---------- */
.demo-block { margin: 26px 0; }
.demo {
  border: 1px solid var(--border); border-radius: 11px; overflow: hidden;
  background: #1e2030; box-shadow: var(--shadow);
}
.demo-head {
  display: flex; align-items: center; gap: 10px; padding: 10px 14px;
  background: #2a2d40; border-bottom: 1px solid #383b52;
}
.demo-title { color: #cbd5e1; font-size: 13.5px; font-weight: 600; flex: 1; display: flex; align-items: center; gap: 7px; }
.demo-lang {
  font-size: 11px; padding: 2px 8px; border-radius: 5px;
  background: #4f46e5; color: #fff; font-weight: 700; text-transform: uppercase;
}
.demo-btn {
  padding: 4px 13px; border-radius: 6px; font-size: 12.5px; font-weight: 700;
  background: #4f46e5; color: #fff; transition: .15s;
}
.demo-btn:hover:not(:disabled) { background: #6366f1; }
.demo-btn:disabled { opacity: .5; cursor: wait; }
.demo-btn.reset { background: transparent; color: #94a3b8; border: 1px solid #4b5069; }
.demo-btn.reset:hover { background: #383b52; color: #cbd5e1; }

.demo-editor {
  display: grid; grid-template-columns: 1fr 1fr; gap: 0; min-height: 200px;
}
.demo-code {
  background: #1e2030; color: #e4e7ee; padding: 15px 17px; overflow-x: auto;
  font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: 13px; line-height: 1.7;
  border-right: 1px solid #383b52;
}
.demo-code textarea {
  width: 100%; min-height: 180px; background: transparent; border: none; outline: none;
  color: #e4e7ee; font-family: inherit; font-size: inherit; line-height: inherit;
  resize: vertical;
}
.demo-output {
  background: #171922; color: #cbd5e1; padding: 15px 17px; overflow-y: auto;
  font-family: ui-monospace, "SF Mono", Menlo, monospace; font-size: 13px; line-height: 1.7;
  white-space: pre-wrap; word-break: break-word; max-height: 420px;
}
.demo-output .err { color: #f87171; }
.demo-output .ok { color: #4ade80; }
.demo-output .info { color: #64748b; font-style: italic; }
.demo-status {
  padding: 6px 14px; background: #2a2d40; border-top: 1px solid #383b52;
  font-size: 12px; color: #94a3b8; display: flex; align-items: center; gap: 8px;
}
.demo-status .spinner {
  width: 11px; height: 11px; border: 2px solid #4b5069; border-top-color: #818cf8;
  border-radius: 50%; animation: spin .7s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 860px) {
  .demo-editor { grid-template-columns: 1fr; }
  .demo-code { border-right: none; border-bottom: 1px solid #383b52; }
}

/* ---------- 底部导航 ---------- */
.lesson-nav { display: flex; justify-content: space-between; gap: 16px; margin-top: 28px; }
.lesson-nav a {
  padding: 13px 20px; border: 1px solid var(--border); border-radius: 10px;
  text-decoration: none; color: var(--text); background: var(--surface);
  transition: .15s; max-width: 46%;
}
.lesson-nav a:hover { border-color: var(--primary); background: var(--primary-soft); text-decoration: none; }
.lesson-nav .dir { font-size: 12px; color: var(--text-dim); margin-bottom: 2px; }
.lesson-nav .ttl { font-size: 14.5px; font-weight: 600; }
.lesson-nav .next { margin-left: auto; text-align: right; }
.lesson-nav .disabled { opacity: .4; pointer-events: none; }

/* ---------- 课时工具条 ---------- */
.lesson-tools {
  display: flex; align-items: center; gap: 12px; flex-wrap: wrap;
  padding: 14px 18px; background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); margin-top: 18px;
}
.lesson-tools .spacer { margin-left: auto; }

/* ---------- 测验 ---------- */
.quiz-wrap { max-width: 720px; margin: 0 auto; }
.quiz-q { padding: 18px 0; border-bottom: 1px solid var(--border); }
.quiz-q:last-child { border: none; }
.quiz-stem { font-size: 15.5px; font-weight: 600; margin-bottom: 13px; line-height: 1.6; }
.quiz-opt {
  display: flex; align-items: center; gap: 11px; padding: 11px 16px;
  border: 1px solid var(--border); border-radius: 9px; margin-bottom: 8px;
  cursor: pointer; transition: .14s; font-size: 14.5px;
}
.quiz-opt:hover { border-color: var(--primary); background: var(--primary-soft); }
.quiz-opt.selected { border-color: var(--primary); background: var(--primary-soft); font-weight: 600; }
.quiz-opt input { margin: 0; accent-color: var(--primary); }
.quiz-blank {
  width: 100%; padding: 10px 14px; border: 1px solid var(--border);
  border-radius: 9px; font-size: 15px;
}
.quiz-blank:focus { outline: none; border-color: var(--primary); }

.quiz-result {
  padding: 26px; border-radius: var(--radius); text-align: center; margin-bottom: 24px;
}
.quiz-result.pass { background: var(--success-soft); border: 1px solid #a7f3d0; }
.quiz-result.fail { background: #fffbeb; border: 1px solid #fde68a; }
.quiz-score { font-size: 46px; font-weight: 800; letter-spacing: -1.5px; margin-bottom: 6px; }
.quiz-result.pass .quiz-score { color: var(--success); }
.quiz-result.fail .quiz-score { color: var(--warn); }
.quiz-explain {
  padding: 13px 16px; background: var(--bg); border-radius: 9px;
  font-size: 14px; margin-top: 9px; text-align: left;
}
.quiz-explain.correct { border-left: 3px solid var(--success); }
.quiz-explain.wrong { border-left: 3px solid var(--danger); }

/* ---------- 表格 ---------- */
.table { width: 100%; border-collapse: collapse; font-size: 14.5px; }
.table th, .table td { padding: 12px 15px; border-bottom: 1px solid var(--border); text-align: left; }
.table th { font-weight: 700; font-size: 13px; color: var(--text-dim); text-transform: uppercase; letter-spacing: .3px; }
.table tbody tr:hover { background: #fafbfd; }

/* ---------- 学习面板 ---------- */
.progress-card { display: flex; align-items: center; gap: 22px; padding: 22px 24px; }
.ring { position: relative; width: 76px; height: 76px; flex-shrink: 0; }
.ring svg { transform: rotate(-90deg); }
.ring circle { fill: none; stroke-width: 8; }
.ring .bg { stroke: #e9ecf3; }
.ring .fg { stroke: url(#ringGrad); stroke-linecap: round; transition: stroke-dashoffset .6s; }
.ring-text {
  position: absolute; inset: 0; display: flex; align-items: center; justify-content: center;
  font-size: 17px; font-weight: 700;
}

/* ---------- 统计块 ---------- */
.stat-box { padding: 20px 22px; }
.stat-box b { display: block; font-size: 29px; font-weight: 800; letter-spacing: -.8px; margin-bottom: 3px; }
.stat-box span { font-size: 13.5px; color: var(--text-dim); }
.stat-box .up { color: var(--success); font-size: 12.5px; font-weight: 600; }

/* ---------- 活动热力 ---------- */
.heatmap { display: grid; grid-auto-flow: column; grid-template-rows: repeat(7, 12px); gap: 3px; }
.heat-cell { width: 12px; height: 12px; border-radius: 3px; background: #eceef4; }
.heat-1 { background: #c7d2fe; }
.heat-2 { background: #a5b4fc; }
.heat-3 { background: #818cf8; }
.heat-4 { background: #4f46e5; }

/* ---------- 空态 ---------- */
.empty { text-align: center; padding: 64px 20px; color: var(--text-dim); }
.empty .ic { font-size: 46px; margin-bottom: 16px; opacity: .5; }
.empty h3 { font-size: 18px; color: var(--text); margin-bottom: 8px; }

/* ---------- 骨架屏 ---------- */
.skeleton { background: linear-gradient(90deg, #eef0f5 25%, #f6f7fa 50%, #eef0f5 75%); background-size: 200% 100%; animation: shimmer 1.4s infinite; border-radius: 8px; }
@keyframes shimmer { 0% { background-position: 200% 0; } 100% { background-position: -200% 0; } }

/* ---------- Toast ---------- */
#toast-root { position: fixed; top: 78px; right: 24px; z-index: 9999; display: flex; flex-direction: column; gap: 10px; }
.toast {
  padding: 13px 20px; border-radius: 10px; font-size: 14.5px; font-weight: 500;
  box-shadow: var(--shadow-lg); background: var(--surface); border: 1px solid var(--border);
  animation: slideIn .25s; max-width: 380px;
}
.toast.success { border-left: 3px solid var(--success); }
.toast.error { border-left: 3px solid var(--danger); }
.toast.info { border-left: 3px solid var(--primary); }
@keyframes slideIn { from { opacity: 0; transform: translateX(24px); } }

/* ---------- 页脚 ---------- */
.footer { padding: 40px 0; border-top: 1px solid var(--border); margin-top: 56px; text-align: center; color: var(--text-dim); font-size: 13.5px; }

/* ---------- 响应式 ---------- */
@media (max-width: 960px) {
  .hero-inner { flex-direction: column; gap: 36px; }
  .hero h1 { font-size: 34px; }
  .learn-layout { grid-template-columns: 1fr; }
  .outline { position: static; max-height: none; margin-bottom: 8px; }
  .lesson-content { padding: 26px 22px; }
  .nav { display: none; }
}
@media (max-width: 560px) {
  .container { padding: 0 16px; }
  .hero { padding: 40px 0 32px; }
  .hero h1 { font-size: 27px; }
  .hero-stats { gap: 22px; }
  .lesson-content { padding: 20px 16px; }
  .card { padding: 18px; }
}
/* ============ AI 课程工作台 ============ */
.table-wrap{overflow-x:auto;-webkit-overflow-scrolling:touch}
.table-wrap .table{min-width:560px}

/* AI 生成输入框 */
#ai-prompt{transition:border-color .2s,box-shadow .2s}
#ai-prompt:focus{outline:none;border-color:var(--primary);box-shadow:0 0 0 3px rgba(99,102,241,.12)}

/* 生成进度条动画 */
@keyframes ai-indeterminate{0%{margin-left:-8%}100%{margin-left:100%}}
#ai-bar{transition:width .4s ease}
#ai-stage{font-weight:600}

/* 示例按钮:hover 时高亮 */
[data-ai-example]{transition:background .15s,border-color .15s}
[data-ai-example]:hover{background:var(--primary);border-color:var(--primary);color:#fff}

/* 表单行内的列（AI 配置页用） */
.form-group.col{flex:1;min-width:0}
.form-group.col label{margin-bottom:5px}
.form-group.col input,.form-group.col select{width:100%}

/* 密钥输入框用等宽字体，避免长密钥难读 */
#ai-apikey{font-family:ui-monospace,Menlo,monospace;font-size:13px}

/* ============================================================
   课程查看器（HTML 单文件课程在线学习）
   ============================================================ */
.player {
  display: flex;
  flex-direction: column;
  height: calc(100vh - 64px);
  background: var(--bg, #f6f7fb);
}
.player-bar {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 10px 18px;
  background: var(--surface, #fff);
  border-bottom: 1px solid var(--border, #e4e7ee);
  flex-wrap: wrap;
}
.player-title {
  font-size: 15px;
  font-weight: 700;
  max-width: 320px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.player-note { flex: 1; min-width: 0; font-size: 12.5px; color: var(--text-dim, #6b7280);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.player-progress { display: flex; align-items: center; gap: 9px; font-size: 13px; color: var(--text-dim, #6b7280); }
.player-progress .progress-bar { margin-top: 0; width: 150px; }
.player-actions { margin-left: auto; display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.player-frame {
  flex: 1;
  width: 100%;
  border: none;
  background: #fff;
  min-height: 0;
}
@media (max-width: 720px) {
  .player-title { max-width: 140px; }
  .player-progress .progress-bar { width: 90px; }
}

/* AI 生成前的「已有相似课程」提醒 */
.dup-warn {
  border:1px solid var(--border); border-radius:14px; padding:20px 22px;
  background:var(--surface); margin-top:18px;
}
.dup-warn.high { border-color:rgba(245,158,11,.5); background:rgba(245,158,11,.06); }
.dup-head { display:flex; gap:12px; align-items:flex-start; margin-bottom:16px; }
.dup-ic { font-size:22px; line-height:1.2; }
.dup-head b { font-size:16px; }
.dup-head p { font-size:13.5px; color:var(--text-dim); margin:5px 0 0; line-height:1.6; }
.dup-list { display:flex; flex-direction:column; gap:10px; }
.dup-item {
  display:flex; gap:14px; align-items:center; text-decoration:none; color:inherit;
  border:1px solid var(--border); border-radius:11px; padding:12px 14px;
  background:var(--card); transition:border-color .15s, transform .15s;
}
.dup-item:hover { border-color:var(--primary); transform:translateX(2px); }
.dup-score {
  flex:0 0 auto; width:56px; text-align:center; font-weight:800; font-size:17px; color:var(--primary);
  line-height:1.1;
}
.dup-score span { display:block; font-size:11px; font-weight:500; color:var(--text-dim); margin-top:2px; }
.dup-body { min-width:0; }
.dup-body b { font-size:14.5px; }
.dup-body p { font-size:13px; color:var(--text-dim); margin:3px 0 4px; }
.dup-meta { font-size:12px; color:var(--text-dim); }
.dup-actions { display:flex; gap:10px; flex-wrap:wrap; margin-top:18px; }
.dup-tip { font-size:12.5px; color:var(--text-dim); margin:12px 0 0; }

/* 内容不明确：给「这样说不行 / 这样说可以」的对照，比一句报错有用 */
.dup-warn.unclear { border-color:rgba(99,102,241,.45); background:rgba(99,102,241,.05); }
.unclear-pair { display:grid; grid-template-columns:1fr 1fr; gap:12px; margin:16px 0 4px; }
.unclear-col { border-radius:10px; padding:12px 14px; font-size:13px; }
.unclear-col b { display:block; font-size:12.5px; margin-bottom:8px; }
.unclear-col p { margin:0 0 5px; color:var(--text-dim); }
.unclear-col.bad { background:rgba(239,68,68,.07); border:1px solid rgba(239,68,68,.25); }
.unclear-col.bad b { color:#b91c1c; }
.unclear-col.good { background:rgba(16,185,129,.07); border:1px solid rgba(16,185,129,.28); }
.unclear-col.good b { color:#047857; }
.unclear-col.good p { color:var(--text); }
.unclear-examples { display:flex; flex-wrap:wrap; gap:8px; align-items:center; margin-top:14px; font-size:13px; color:var(--text-dim); }
@media (max-width:640px) { .unclear-pair { grid-template-columns:1fr; } }