/* ===========================================================
   前端学习笔记 · 全站样式
   =========================================================== */

:root {
  --bg: #f6f8fb;
  --surface: #ffffff;
  --text: #1f2933;
  --text-soft: #52606d;
  --text-muted: #7b8794;
  --border: #e4e7eb;
  --primary: #2f6fed;
  --primary-dark: #1c4fbb;
  --primary-soft: #eaf1ff;
  --accent: #16a394;
  --radius: 14px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, .06);
  --shadow-md: 0 8px 24px rgba(15, 23, 42, .08);
  --maxw: 1080px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  --mono: "SFMono-Regular", "JetBrains Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

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

img { max-width: 100%; }

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- 顶部导航 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .88);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 18px;
  color: var(--text);
}
.brand .logo {
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border-radius: 9px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff; font-weight: 800; font-size: 15px;
}
.nav-links {
  display: flex;
  gap: 6px;
  list-style: none;
  margin: 0; padding: 0;
}
.nav-links a {
  display: inline-block;
  padding: 8px 14px;
  border-radius: 9px;
  color: var(--text-soft);
  font-size: 15px;
  transition: background .15s, color .15s;
}
.nav-links a:hover { background: var(--primary-soft); color: var(--primary-dark); }
.nav-links a.active { background: var(--primary); color: #fff; }

.nav-toggle {
  display: none;
  border: 1px solid var(--border);
  background: var(--surface);
  border-radius: 9px;
  width: 40px; height: 40px;
  font-size: 18px;
  cursor: pointer;
}

/* ---------- 通用区块 ---------- */
.section { padding: 56px 0; }
.section-title {
  font-size: 26px;
  margin: 0 0 6px;
}
.section-sub {
  color: var(--text-muted);
  margin: 0 0 28px;
}

/* ---------- Hero ---------- */
.hero {
  padding: 72px 0 60px;
  background:
    radial-gradient(900px 400px at 80% -10%, #dbe7ff 0, transparent 60%),
    radial-gradient(700px 360px at 0% 10%, #d6f5ee 0, transparent 55%);
}
.hero h1 {
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1.2;
  margin: 0 0 16px;
  letter-spacing: -.5px;
}
.hero h1 .grad {
  background: linear-gradient(120deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hero p {
  font-size: 18px;
  color: var(--text-soft);
  max-width: 640px;
  margin: 0 0 28px;
}
.btn-row { display: flex; gap: 12px; flex-wrap: wrap; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform .12s, box-shadow .15s, background .15s;
}
.btn-primary { background: var(--primary); color: #fff; box-shadow: var(--shadow-sm); }
.btn-primary:hover { background: var(--primary-dark); color: #fff; transform: translateY(-1px); }
.btn-ghost { background: var(--surface); color: var(--text); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--primary); color: var(--primary-dark); }

.stats {
  display: flex;
  gap: 34px;
  margin-top: 40px;
  flex-wrap: wrap;
}
.stat b { font-size: 26px; color: var(--text); }
.stat span { display: block; color: var(--text-muted); font-size: 14px; }

/* ---------- 卡片网格 ---------- */
.grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); border-color: #cfe0ff; }
.card .icon {
  width: 46px; height: 46px;
  border-radius: 11px;
  display: grid; place-items: center;
  font-size: 22px;
  background: var(--primary-soft);
  margin-bottom: 14px;
}
.card h3 { margin: 0 0 8px; font-size: 18px; }
.card p { margin: 0; color: var(--text-soft); font-size: 15px; }
.tag-list { margin-top: 14px; display: flex; gap: 8px; flex-wrap: wrap; }
.tag {
  font-size: 12px;
  padding: 3px 10px;
  border-radius: 999px;
  background: #eef2f7;
  color: var(--text-muted);
}

/* ---------- 笔记列表 ---------- */
.note-list { list-style: none; margin: 0; padding: 0; display: grid; gap: 16px; }
.note-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 24px;
  box-shadow: var(--shadow-sm);
  transition: border-color .15s, box-shadow .15s;
}
.note-item:hover { border-color: #cfe0ff; box-shadow: var(--shadow-md); }
.note-item .meta { font-size: 13px; color: var(--text-muted); margin-bottom: 6px; }
.note-item h3 { margin: 0 0 8px; font-size: 19px; }
.note-item p { margin: 0; color: var(--text-soft); }

/* ---------- 文章正文 ---------- */
.article {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px;
  box-shadow: var(--shadow-sm);
}
.article h1 { margin-top: 0; }
.article h2 { margin-top: 34px; border-left: 4px solid var(--primary); padding-left: 12px; }
.article pre {
  background: #0f172a;
  color: #e2e8f0;
  padding: 18px;
  border-radius: 10px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
}
.article code {
  font-family: var(--mono);
  background: #eef2f7;
  padding: 2px 6px;
  border-radius: 5px;
  font-size: .92em;
}
.article pre code { background: none; padding: 0; color: inherit; }

/* ---------- 关于页 ---------- */
.about-grid { display: grid; grid-template-columns: 1fr; gap: 24px; }
.timeline { list-style: none; margin: 0; padding: 0; }
.timeline li {
  position: relative;
  padding: 0 0 22px 26px;
  border-left: 2px solid var(--border);
}
.timeline li::before {
  content: "";
  position: absolute; left: -7px; top: 4px;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--primary);
}
.timeline b { display: block; }
.timeline span { color: var(--text-muted); font-size: 13px; }

/* ---------- 页脚 ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--surface);
  margin-top: 40px;
  padding: 34px 0;
  color: var(--text-muted);
  font-size: 14px;
}
.footer-grid {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}
.footer-grid a { color: var(--text-soft); }
.beian {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px dashed var(--border);
  text-align: center;
  line-height: 2;
}
.beian a { color: var(--text-muted); }
.beian a:hover { color: var(--primary); }

/* ---------- 响应式 ---------- */
@media (max-width: 720px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: absolute;
    top: 64px; left: 0; right: 0;
    flex-direction: column;
    gap: 4px;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 12px 20px;
    display: none;
  }
  .nav-links.open { display: flex; }
  .article { padding: 24px; }
  .footer-grid { flex-direction: column; }
}