/* 学员端基础样式（任务 9）。无构建步骤，直接由 Workers assets 提供。 */
:root {
  --fg: #1f2933;
  --muted: #616e7c;
  --line: #e4e7eb;
  --brand: #2563eb;
  --bg: #f7f9fb;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font: 16px/1.6 system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--fg);
  background: var(--bg);
}
a { color: var(--brand); }
.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 20px;
  background: #fff;
  border-bottom: 1px solid var(--line);
}
.site-name { font-weight: 700; font-size: 18px; color: var(--fg); text-decoration: none; }
.site-header nav a { margin-left: 16px; }
.container { max-width: 1000px; margin: 0 auto; padding: 20px; }
.site-intro h1 { margin: 8px 0 4px; }
.site-intro p { color: var(--muted); }
.empty { color: var(--muted); }

.cat-filter { display: flex; gap: 8px; flex-wrap: wrap; margin: 16px 0; }
.cat-filter a {
  padding: 4px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  text-decoration: none;
  color: var(--fg);
  background: #fff;
}
.cat-filter a.active { background: var(--brand); color: #fff; border-color: var(--brand); }

.course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
.course-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  overflow: hidden;
  text-decoration: none;
  color: inherit;
}
.course-card .cover { width: 100%; aspect-ratio: 16 / 9; object-fit: cover; display: block; background: var(--line); }
.course-card-body { padding: 12px; }
.course-card-body h3 { margin: 0 0 6px; }
.price { color: #b91c1c; font-weight: 600; margin: 0; }

.badge {
  display: inline-block;
  margin-left: 8px;
  padding: 1px 8px;
  font-size: 12px;
  border-radius: 999px;
  background: #ecfdf5;
  color: #047857;
  border: 1px solid #a7f3d0;
  white-space: nowrap;
}
.badge.paused { background: #fef3c7; color: #92400e; border-color: #fde68a; }
.chapter-list { list-style: none; padding: 0; margin: 0; }
.chapter-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  padding: 10px 12px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
}
.chapter-list li.locked, .chapter-list li.locked a { color: var(--muted); }
.chapter-list li.current { background: #eff6ff; }
.chapter-list .unlock { margin-left: auto; }

.chapter-layout { display: grid; grid-template-columns: 280px 1fr; gap: 20px; align-items: start; }
.chapter-side, .toc-top {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 8px;
}
.chapter-side h2 { font-size: 15px; margin: 6px 10px; }
.toc-top { display: none; margin-bottom: 16px; }
.chapter-main h1 { margin-top: 0; }
video { width: 100%; max-height: 480px; background: #000; border-radius: 10px; }
.markdown {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 16px 20px;
  margin: 16px 0;
  overflow-wrap: break-word;
}
.markdown img { max-width: 100%; }
.markdown pre { overflow: auto; background: #f3f4f6; padding: 12px; border-radius: 8px; }
.chapter-actions { display: flex; gap: 16px; align-items: center; flex-wrap: wrap; }

.intro-cover { max-width: 480px; width: 100%; border-radius: 10px; display: block; }
.unlocked-note { margin-top: 16px; }
.buy { background: #fff; border: 1px solid var(--line); border-radius: 10px; padding: 16px; margin-top: 24px; }
.buy fieldset { border: 0; padding: 0; margin: 12px 0; display: flex; gap: 16px; }
.buy legend { font-weight: 600; }
.buy button { margin: 0 12px 8px 0; }

button, .button {
  display: inline-block;
  padding: 8px 16px;
  border-radius: 8px;
  border: 1px solid var(--brand);
  background: var(--brand);
  color: #fff;
  font-size: 15px;
  cursor: pointer;
  text-decoration: none;
}
button.secondary, .button.secondary { background: #fff; color: var(--brand); }
button:disabled { opacity: 0.6; cursor: default; }

table { width: 100%; border-collapse: collapse; background: #fff; border: 1px solid var(--line); }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); }

.login-form {
  max-width: 380px;
  margin: 40px auto;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 24px;
  display: grid;
  gap: 16px;
}
.login-form label { display: grid; gap: 6px; }
.login-form input {
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: 16px;
}
.code-row { display: flex; gap: 8px; }
.code-row input { flex: 1; }
.msg { color: #b91c1c; min-height: 1.5em; margin: 0; }

@media (max-width: 720px) {
  .chapter-layout { grid-template-columns: 1fr; }
  .chapter-side { display: none; }
  .toc-top { display: block; }
  .toc-top summary { cursor: pointer; font-weight: 600; }
  .container { padding: 12px; }
}