:root {
  --amber-50: #FAEEDA;
  --amber-100: #FAC775;
  --amber-200: #EF9F27;
  --amber-400: #BA7517;
  --amber-600: #854F0B;
  --amber-800: #633806;
  --amber-900: #412402;
  --gray-50: #F1EFE8;
  --gray-100: #D3D1C7;
  --gray-400: #888780;
  --gray-600: #5F5E5A;
  --gray-800: #444441;
  --gray-900: #2C2C2A;
  --white: #FFFFFF;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --shadow: 0 4px 24px rgba(65, 36, 2, 0.08);
}

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

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  color: var(--gray-900);
  background: var(--white);
  font-size: 14px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
input, select, textarea { font-family: inherit; font-size: 14px; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }

/* 顶部导航 */
.nav { position: sticky; top: 0; z-index: 100; background: var(--white); border-bottom: 1px solid var(--gray-100); height: 64px; display: flex; align-items: center; }
.nav .container { display: flex; align-items: center; gap: 40px; }
.nav-brand { display: flex; align-items: center; gap: 10px; font-size: 24px; font-weight: 700; letter-spacing: .5px; color: var(--amber-900); }
.nav-brand .logo { width: 38px; height: 38px; background: var(--amber-200); border-radius: 8px; display: flex; align-items: center; justify-content: center; color: var(--white); font-size: 21px; font-weight: 700; }
.nav-menu { display: flex; gap: 28px; flex: 1; }
.nav-menu a { font-size: 14px; color: var(--gray-600); padding: 4px 0; border-bottom: 2px solid transparent; transition: all .2s; }
.nav-menu a:hover, .nav-menu a.active { color: var(--amber-600); border-bottom-color: var(--amber-200); }
.nav-actions { display: flex; gap: 10px; align-items: center; }
.nav-user { font-size: 13px; color: var(--gray-600); }
.nav-user .name { color: var(--amber-600); font-weight: 500; }

.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; padding: 8px 18px; border-radius: var(--radius-md); font-size: 14px; font-weight: 500; transition: all .2s; border: 1px solid transparent; white-space: nowrap; }
.btn-primary { background: var(--amber-200); color: var(--white); }
.btn-primary:hover { background: var(--amber-400); }
.btn-outline { background: var(--white); color: var(--amber-600); border-color: var(--amber-200); }
.btn-outline:hover { background: var(--amber-50); }
.btn-ghost { background: transparent; color: var(--gray-600); }
.btn-ghost:hover { color: var(--amber-600); }
.btn-block { width: 100%; }
.btn-lg { padding: 12px 24px; font-size: 15px; }
.btn-sm { padding: 5px 12px; font-size: 12px; }

/* 通用区块 */
.section { padding: 64px 0; }
.section-amber { background: var(--amber-50); }
.section-title { font-size: 26px; font-weight: 600; color: var(--gray-900); text-align: center; margin: 0 0 8px; }
.section-sub { font-size: 14px; color: var(--gray-600); text-align: center; margin-bottom: 40px; }

/* 卡片 */
.card { background: var(--white); border: 1px solid var(--gray-100); border-radius: var(--radius-lg); overflow: hidden; transition: box-shadow .2s, transform .2s; }
.card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }

/* 课程卡片 */
.course-card { display: flex; flex-direction: column; }
.course-card .cover { height: 170px; background: var(--amber-100); position: relative; display: flex; align-items: center; justify-content: center; overflow: hidden; }
.course-card .cover img { width: 100%; height: 100%; object-fit: cover; }
.course-card .badge { position: absolute; top: 12px; left: 12px; background: rgba(255,255,255,.92); color: var(--amber-600); font-size: 11px; padding: 3px 10px; border-radius: 12px; font-weight: 500; }
.course-card .badge-hot { background: var(--amber-200); color: var(--white); }
.course-card .body { padding: 16px; flex: 1; display: flex; flex-direction: column; }
.course-card .title { font-size: 15px; font-weight: 600; color: var(--gray-900); margin-bottom: 6px; line-height: 1.4; }
.course-card .subtitle { font-size: 12px; color: var(--gray-600); margin-bottom: 12px; flex: 1; }
.course-card .meta { display: flex; justify-content: space-between; align-items: center; font-size: 12px; color: var(--gray-400); margin-bottom: 10px; }
.course-card .price-row { display: flex; align-items: baseline; gap: 8px; }
.course-card .price { font-size: 18px; font-weight: 600; color: var(--amber-600); }
.course-card .price-old { font-size: 12px; color: var(--gray-400); text-decoration: line-through; }

/* 网格 */
.grid { display: grid; gap: 20px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }

@media (max-width: 900px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .nav-menu { display: none; }
}
@media (max-width: 600px) {
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .section { padding: 40px 0; }
  .section-title { font-size: 22px; }
}

/* 表单 */
.form-group { margin-bottom: 18px; }
.form-label { display: block; font-size: 13px; color: var(--gray-800); margin-bottom: 6px; font-weight: 500; }
.form-control { width: 100%; padding: 11px 14px; border: 1px solid var(--gray-100); border-radius: var(--radius-md); font-size: 14px; color: var(--gray-900); background: var(--white); transition: border-color .2s, box-shadow .2s; }
.form-control:focus { outline: none; border-color: var(--amber-200); box-shadow: 0 0 0 3px rgba(239,159,39,.12); }
.form-control:disabled { background: var(--gray-50); color: var(--gray-400); }
.form-hint { font-size: 12px; color: var(--gray-400); margin-top: 6px; }
.form-error { font-size: 12px; color: #c0392b; margin-top: 6px; }

.input-group { display: flex; gap: 10px; }
.input-group .form-control { flex: 1; }

/* 标签 chip */
.chip { display: inline-flex; align-items: center; padding: 4px 12px; border-radius: 14px; font-size: 12px; background: var(--amber-50); color: var(--amber-600); border: 1px solid var(--amber-100); }
.chip.active { background: var(--amber-200); color: var(--white); border-color: var(--amber-200); }

/* 页脚 */
.footer { background: var(--amber-900); color: var(--amber-100); padding: 32px 0 20px; }
.footer .container { display: flex; flex-wrap: wrap; gap: 24px; justify-content: space-between; }
.footer h4 { font-size: 15px; color: var(--white); margin-bottom: 12px; font-weight: 600; }
.footer p, .footer a { font-size: 13px; color: var(--amber-100); opacity: .85; line-height: 1.8; }
.footer a:hover { opacity: 1; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.12); margin-top: 24px; padding-top: 16px; text-align: center; font-size: 12px; opacity: .7; }
.footer-beian { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; margin-top: 8px; }

/* 空状态 */
.empty { text-align: center; padding: 60px 20px; color: var(--gray-400); }
.empty .icon { font-size: 40px; margin-bottom: 12px; opacity: .5; }

/* 访问统计条 */
.visit-bar { background: var(--amber-50); border-top: 1px solid var(--amber-100); padding: 10px 0; font-size: 12px; color: var(--amber-600); }
.visit-bar .container { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; }

/* 提示 toast */
.toast { position: fixed; top: 80px; left: 50%; transform: translateX(-50%); background: var(--gray-900); color: var(--white); padding: 10px 20px; border-radius: var(--radius-md); font-size: 13px; z-index: 9999; opacity: 0; pointer-events: none; transition: opacity .25s, top .25s; }
.toast.show { opacity: 1; top: 90px; }
.toast.error { background: #c0392b; }
.toast.success { background: var(--amber-600); }

/* 标题小工具 */
.flex { display: flex; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.flex-center { display: flex; align-items: center; }
.gap-8 { gap: 8px; } .gap-12 { gap: 12px; } .gap-16 { gap: 16px; } .gap-24 { gap: 24px; }
.mt-8 { margin-top: 8px; } .mt-16 { margin-top: 16px; } .mt-24 { margin-top: 24px; } .mt-40 { margin-top: 40px; }
.mb-8 { margin-bottom: 8px; } .mb-16 { margin-bottom: 16px; } .mb-24 { margin-bottom: 24px; } .mb-40 { margin-bottom: 40px; }
.text-center { text-align: center; }
.text-muted { color: var(--gray-400); }
.text-amber { color: var(--amber-600); }
.text-sm { font-size: 12px; } .text-lg { font-size: 16px; } .text-xl { font-size: 20px; }
.fw-500 { font-weight: 500; } .fw-600 { font-weight: 600; }