* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
  --brand: #2563eb;       /* 蓝 */
  --brand-dark: #1e40af;
  --ink: #1f2937;
  --muted: #6b7280;
  --bg: #f8fafc;
  --card: #ffffff;
  --line: #e5e7eb;
  --ok: #16a34a;
  --warn: #d97706;
  --danger: #dc2626;
}
html { scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.7;
}
a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

/* 顶栏 */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: #ffffff; border-bottom: 1px solid var(--line);
  box-shadow: 0 1px 6px rgba(0,0,0,.04);
}
.topbar-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; gap: 24px; height: 60px;
}
.brand { font-size: 20px; font-weight: 800; color: var(--ink); }
.brand span { color: var(--brand); }
.nav { display: flex; gap: 4px; margin-left: auto; }
.nav a {
  padding: 8px 14px; border-radius: 8px; color: var(--muted);
  font-weight: 600; font-size: 14px;
}
.nav a:hover { background: #eff6ff; color: var(--brand); text-decoration: none; }
.nav a.active { background: var(--brand); color: #fff; }

/* 容器 */
.wrap { max-width: 1100px; margin: 0 auto; padding: 28px 20px 60px; }
.wrap.narrow { max-width: 860px; }

/* 首页 hero */
.hero { text-align: center; padding: 60px 20px 30px; }
.hero h1 { font-size: 40px; font-weight: 800; letter-spacing: -0.5px; }
.hero h1 span { color: var(--brand); }
.hero p { color: var(--muted); max-width: 640px; margin: 16px auto 0; font-size: 17px; }
.hero .cta { margin-top: 26px; display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 12px 26px; border-radius: 10px; font-weight: 700; font-size: 15px;
}
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); text-decoration: none; color:#fff; }
.btn-ghost { border: 1px solid var(--line); color: var(--ink); background: #fff; }
.btn-ghost:hover { border-color: var(--brand); color: var(--brand); text-decoration: none; }

/* 模块入口卡片 */
.grid { display: grid; gap: 18px; }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 900px) { .grid-4,.grid-3 { grid-template-columns: repeat(2,1fr); } }
@media (max-width: 600px) { .grid-4,.grid-3,.grid-2 { grid-template-columns: 1fr; } }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 22px;
  transition: transform .12s, box-shadow .12s;
}
.card:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,.07); }
.card .ico { font-size: 30px; }
.card h3 { margin: 10px 0 6px; font-size: 17px; }
.card p { color: var(--muted); font-size: 14px; }
.card .tag { display:inline-block; font-size: 12px; color: var(--brand); background:#eff6ff; border-radius: 6px; padding: 2px 8px; margin-top: 8px; }

/* 页面标题 */
.page-head { margin-bottom: 24px; }
.page-head h1 { font-size: 28px; }
.page-head .desc { color: var(--muted); margin-top: 6px; }

/* 列表 */
.list-item {
  display: flex; gap: 16px; align-items: flex-start;
  background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px 18px; margin-bottom: 12px;
}
.list-item:hover { border-color: var(--brand); }
.list-item .idx { font-size: 24px; font-weight: 800; color: #d1d5db; min-width: 36px; }
.list-item h3 { font-size: 16px; }
.list-item p { color: var(--muted); font-size: 13px; margin-top: 2px; }
.list-item .meta { font-size: 12px; color: var(--muted); margin-top: 6px; }
.pill {
  display: inline-block; font-size: 12px; font-weight: 600; padding: 2px 10px; border-radius: 999px;
}
.pill.lv1 { background: #ecfdf5; color: #047857; }
.pill.lv2 { background: #eff6ff; color: #2563eb; }
.pill.lv3 { background: #fef3c7; color: #b45309; }
.pill.lv4 { background: #fee2e2; color: #b91c1c; }

/* 教程正文 */
.article { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 34px 40px; }
.article h1 { font-size: 28px; margin-bottom: 6px; }
.article h2 { font-size: 21px; margin: 28px 0 12px; padding-bottom: 8px; border-bottom: 1px solid var(--line); }
.article h3 { font-size: 17px; margin: 20px 0 8px; }
.article p { margin: 10px 0; }
.article ul, .article ol { margin: 10px 0 10px 22px; }
.article li { margin: 4px 0; }
.article blockquote {
  border-left: 4px solid var(--brand); background: #eff6ff; padding: 10px 16px;
  border-radius: 0 8px 8px 0; margin: 14px 0; color: #374151;
}
.article code:not(pre code) {
  background: #f3f4f6; color: #be185d; padding: 2px 6px; border-radius: 5px; font-size: .9em;
}
.article pre {
  background: #f6f8fa; border: 1px solid var(--line); border-radius: 10px; padding: 16px;
  overflow-x: auto; margin: 14px 0;
}
.article pre code { background: none; color: inherit; font-family: "SFMono-Regular", Consolas, monospace; font-size: 14px; }
.article table { border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 14px; }
.article th, .article td { border: 1px solid var(--line); padding: 8px 12px; text-align: left; }
.article th { background: #f8fafc; }
.article a { text-decoration: underline; }
.prevnext { display: flex; justify-content: space-between; gap: 14px; margin-top: 28px; }
.prevnext a { flex:1; border: 1px solid var(--line); background:#fff; border-radius: 10px; padding: 12px 16px; }
.prevnext a:hover { border-color: var(--brand); text-decoration: none; }
.prevnext .pn { font-size: 12px; color: var(--muted); }
.prevnext .t { font-weight: 700; color: var(--ink); }

/* 题库 */
.quiz-box { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 30px; max-width: 720px; margin: 0 auto; }
.q-progress { display: flex; justify-content: space-between; align-items: center; margin-bottom: 18px; color: var(--muted); font-size: 14px; }
.bar { height: 8px; background: #e5e7eb; border-radius: 999px; overflow: hidden; margin: 12px 0 20px; }
.bar i { display:block; height:100%; background: var(--brand); transition: width .3s; }
.q-text { font-size: 19px; font-weight: 700; margin-bottom: 20px; }
.q-opts { display: flex; flex-direction: column; gap: 10px; }
.opt {
  border: 1.5px solid var(--line); border-radius: 10px; padding: 13px 16px; cursor: pointer;
  transition: border-color .12s, background .12s; font-size: 15px;
}
.opt:hover { border-color: var(--brand); background: #eff6ff; }
.opt.correct { border-color: var(--ok); background: #f0fdf4; }
.opt.wrong { border-color: var(--danger); background: #fef2f2; }
.opt.disabled { pointer-events: none; }
.q-result { text-align: center; padding: 20px 0; }
.q-result .score { font-size: 46px; font-weight: 800; color: var(--brand); }
.q-result .st { color: var(--muted); margin-top: 8px; }
.quiz-actions { display: flex; justify-content: space-between; gap: 12px; margin-top: 24px; }
.quiz-actions .btn { flex: 1; text-align: center; }

/* 代码示例 */
.snippet-box { background: var(--card); border: 1px solid var(--line); border-radius: 12px; overflow: hidden; margin-bottom: 16px; }
.snippet-box .s-head { padding: 12px 16px; border-bottom: 1px solid var(--line); display: flex; justify-content: space-between; align-items: center; }
.snippet-box .s-head h3 { font-size: 15px; }
.snippet-box .s-head .cat { font-size: 12px; color: var(--brand); background:#eff6ff; padding: 2px 8px; border-radius: 6px; }
.snippet-box pre { margin: 0; background: #f6f8fa; padding: 16px; overflow-x: auto; }
.snippet-box pre code { font-family: "SFMono-Regular", Consolas, monospace; font-size: 13.5px; }

/* 类库 */
.lib-tag { display: inline-block; font-size: 12px; background:#eef2ff; color:#4338ca; border-radius:6px; padding:2px 8px; margin:0 4px 4px 0; }

/* footer */
.footer { border-top: 1px solid var(--line); padding: 24px 20px; text-align: center; color: var(--muted); font-size: 13px; }

/* misc */
.empty { text-align:center; color:var(--muted); padding:60px 0; }
.hljs { background: transparent !important; }

/* 付费墙 */
.paywall { border: 2px dashed var(--brand); border-radius: 14px; padding: 30px 24px; text-align: center; margin: 24px 0; background: #f8fafc; }
.paywall .lock { font-size: 44px; }
.paywall h3 { font-size: 19px; margin: 10px 0 8px; }
.paywall p { color: var(--muted); font-size: 14px; margin: 6px 0; }
.paywall .price { font-size: 16px; color: var(--ink); }
.paywall .price b { color: var(--brand); font-size: 20px; }
.paywall .buy b { color: var(--brand); }
.paywall .code-input { display: flex; gap: 8px; justify-content: center; margin: 16px 0 6px; }
.paywall .code-input input { flex: 1; max-width: 340px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 8px; font-size: 14px; }
.paywall .code-input button { padding: 10px 22px; background: var(--brand); color: #fff; border: none; border-radius: 8px; font-size: 14px; cursor: pointer; }
.paywall .tip { font-weight: 600; min-height: 20px; }
.paywall .note { font-size: 12px !important; color: #999 !important; }

/* 付费标签 */
.paid-tag { display: inline-block; font-size: 11px; background: #fef3c7; color: #b45309; border-radius: 5px; padding: 2px 7px; margin-left: 8px; vertical-align: middle; }

/* ===== 商业首页 ===== */
.hero-badge { display: inline-block; background: #eff6ff; color: var(--brand); border: 1px solid #bfdbfe; border-radius: 999px; padding: 6px 16px; font-size: 13px; margin-bottom: 16px; }
.sec-head { margin: 8px 0 20px; }
.sec-head h2 { font-size: 26px; margin: 0 0 4px; }
.sec-head p { color: var(--muted); margin: 0; }
.free-tag { font-size: 11px; background: #dcfce7; color: #16a34a; border-radius: 5px; padding: 2px 7px; margin-left: 6px; vertical-align: middle; }
.pay-block { background: linear-gradient(180deg, #eff6ff 0%, #ffffff 100%); border: 1.5px solid #bfdbfe; border-radius: 18px; padding: 30px 26px; margin: 34px 0; }
.pay-flag { display: inline-block; background: #fef3c7; color: #b45309; border-radius: 999px; padding: 5px 14px; font-size: 13px; font-weight: 700; margin-bottom: 12px; }
.grid-5 { grid-template-columns: repeat(5, 1fr); }
.pay-item { text-align: center; padding: 16px 8px; background: #fff; border: 1px solid var(--line); border-radius: 12px; }
.pay-item .pi-ico { font-size: 28px; }
.pay-item b { display: block; font-size: 14px; margin: 8px 0 4px; }
.pay-item span { font-size: 12px; color: var(--muted); }
.pay-points { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin: 22px 0; }
.pay-points span { font-size: 13px; color: var(--ink); background: #fff; border: 1px solid var(--line); border-radius: 999px; padding: 6px 14px; }
.buy-bar { text-align: center; background: #fff; border: 1px solid #bfdbfe; border-radius: 14px; padding: 20px; }
.buy-price { font-size: 18px; margin-bottom: 8px; }
.buy-price b { color: var(--brand); font-size: 30px; }
.buy-contact { color: var(--muted); font-size: 14px; margin-bottom: 14px; }
.buy-contact b { color: var(--brand); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }