/* =====================================================
   Henry's Blog — Apple-inspired Design System
   v2.0 (dark mode, covers, toc, progress, search, code)
   ===================================================== */

:root {
  --bg: #ffffff;
  --bg-subtle: #f5f5f7;
  --bg-elev: #ffffff;
  --text: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #a1a1a6;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --accent-soft: rgba(0, 113, 227, 0.1);
  --border: rgba(0, 0, 0, 0.08);
  --card-border: rgba(0, 0, 0, 0.04);
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.06);
  --shadow-hover: 0 14px 40px rgba(0, 0, 0, 0.12);
  --code-bg: #f6f6f8;
  --code-text: #1d1d1f;
  --scrollbar: rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] {
  --bg: #000000;
  --bg-subtle: #161617;
  --bg-elev: #1c1c1e;
  --text: #f5f5f7;
  --text-secondary: #a1a1a6;
  --text-tertiary: #6e6e73;
  --accent: #2997ff;
  --accent-hover: #47a6ff;
  --accent-soft: rgba(41, 151, 255, 0.16);
  --border: rgba(255, 255, 255, 0.12);
  --card-border: rgba(255, 255, 255, 0.06);
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.5);
  --shadow-hover: 0 16px 44px rgba(0, 0, 0, 0.7);
  --code-bg: #1c1c1e;
  --code-text: #f5f5f7;
  --scrollbar: rgba(255, 255, 255, 0.2);
}

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

html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; scroll-padding-top: 70px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text",
    "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  letter-spacing: -0.01em;
  transition: background 0.3s ease, color 0.3s ease;
}

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

.container { max-width: 1080px; margin: 0 auto; padding: 0 32px; }

/* ---------- Reading progress bar ---------- */
.progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), #6aa9ff);
  z-index: 200;
  transition: width 0.1s linear;
}

/* ---------- Navigation (frosted glass) ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 75%, transparent);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 12px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text);
}
.brand span { color: var(--accent); }

.nav-links { display: flex; gap: 4px; list-style: none; align-items: center; }

.nav-links a {
  display: block;
  padding: 8px 14px;
  border-radius: 980px;
  font-size: 15px;
  color: var(--text);
  transition: background 0.25s ease, color 0.25s ease;
}
.nav-links a:hover { background: var(--bg-subtle); }
.nav-links a.active { background: var(--bg-subtle); color: var(--text); }

.nav-actions { display: flex; gap: 8px; align-items: center; }

.icon-btn {
  background: transparent;
  border: none;
  color: var(--text);
  cursor: pointer;
  width: 36px; height: 36px;
  border-radius: 980px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s ease;
}
.icon-btn:hover { background: var(--bg-subtle); }
.icon-btn svg { width: 18px; height: 18px; }

/* ---------- Hero ---------- */
.hero { padding: 88px 0 56px; text-align: center; }

.hero .eyebrow {
  display: inline-block;
  padding: 6px 14px;
  border-radius: 980px;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  margin-bottom: 24px;
}

.hero h1 {
  font-size: clamp(42px, 7vw, 74px);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.06;
  margin-bottom: 18px;
}

.hero p {
  font-size: clamp(18px, 2.5vw, 24px);
  color: var(--text-secondary);
  max-width: 660px;
  margin: 0 auto;
}

/* ---------- Sections ---------- */
.section { padding: 32px 0 60px; }
.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 28px; flex-wrap: wrap; gap: 12px; }
.section-head h2 { font-size: 30px; font-weight: 700; letter-spacing: -0.02em; }

/* ---------- Category filter ---------- */
.filters { display: flex; gap: 8px; flex-wrap: wrap; }
.filter-chip {
  padding: 8px 16px;
  border-radius: 980px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.filter-chip:hover { border-color: var(--accent); color: var(--accent); }
.filter-chip.active { background: var(--accent); border-color: var(--accent); color: #fff; }

/* ---------- Cards ---------- */
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 24px; }

.card {
  display: flex;
  flex-direction: column;
  background: var(--bg-elev);
  border: 1px solid var(--card-border);
  border-radius: 24px;
  overflow: hidden;
  text-decoration: none;
  color: var(--text);
  box-shadow: var(--shadow-card);
  transition: transform 0.35s cubic-bezier(.4,0,.2,1), box-shadow 0.35s cubic-bezier(.4,0,.2,1);
}
.card:hover { transform: translateY(-5px); box-shadow: var(--shadow-hover); }

.cover {
  height: 168px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.02em;
  text-shadow: 0 2px 12px rgba(0,0,0,0.2);
}
.cover.c1 { background: linear-gradient(135deg, #1e3a8a, #3b82f6, #93c5fd); }
.cover.c2 { background: linear-gradient(135deg, #7c3aed, #a855f7, #e9d5ff); }
.cover.c3 { background: linear-gradient(135deg, #0f766e, #14b8a6, #99f6e4); }
.cover.c4 { background: linear-gradient(135deg, #b45309, #f59e0b, #fcd34d); }
.cover.c5 { background: linear-gradient(135deg, #be123c, #f43f5e, #fecdd3); }
.cover.c6 { background: linear-gradient(135deg, #1f2937, #4b5563, #9ca3af); }

.card-body { padding: 22px; display: flex; flex-direction: column; flex: 1; }
.card .tag {
  align-self: flex-start;
  font-size: 12px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 4px 10px;
  border-radius: 980px;
  margin-bottom: 14px;
}
.card h3 { font-size: 20px; font-weight: 600; letter-spacing: -0.02em; line-height: 1.35; margin-bottom: 10px; }
.card p { font-size: 14px; color: var(--text-secondary); flex: 1; margin-bottom: 16px; }
.card .meta { font-size: 12px; color: var(--text-tertiary); display: flex; gap: 8px; align-items: center; }

/* ---------- Article ---------- */
.article-wrap { max-width: 780px; margin: 0 auto; padding: 56px 24px 80px; }

.article .back { display: inline-block; font-size: 14px; color: var(--accent); margin-bottom: 32px; }
.article .back:hover { text-decoration: underline; }

.article header { margin-bottom: 36px; }
.article .tag { font-size: 13px; font-weight: 600; color: var(--accent); }
.article h1 { font-size: clamp(32px, 5vw, 48px); font-weight: 700; letter-spacing: -0.03em; line-height: 1.12; margin: 12px 0 18px; }
.article .lead { font-size: 20px; color: var(--text-secondary); margin-bottom: 20px; }
.article .meta { font-size: 13px; color: var(--text-tertiary); display: flex; flex-wrap: wrap; gap: 12px; align-items: center; padding-bottom: 22px; border-bottom: 1px solid var(--border); margin-bottom: 40px; }

.article h2 { font-size: 27px; font-weight: 700; letter-spacing: -0.02em; margin: 44px 0 16px; scroll-margin-top: 90px; }
.article h3 { font-size: 21px; font-weight: 600; margin: 32px 0 12px; scroll-margin-top: 90px; }
.article p { font-size: 18px; margin-bottom: 1.4em; color: var(--text); }
.article li { font-size: 18px; margin: 4px 0; }
.article ul, .article ol { margin: 0 0 1.4em 24px; }
.article blockquote { border-left: 3px solid var(--accent); padding: 6px 0 6px 20px; margin: 32px 0; font-size: 20px; font-weight: 500; color: var(--text-secondary); }
.article img { max-width: 100%; border-radius: 16px; margin: 24px 0; }
.article code { font-family: "SF Mono", ui-monospace, Menlo, monospace; font-size: 0.9em; background: var(--code-bg); color: var(--accent); padding: 2px 6px; border-radius: 6px; }
.article pre { background: var(--code-bg); color: var(--code-text); border-radius: 14px; padding: 20px; overflow-x: auto; margin: 24px 0; position: relative; font-size: 15px; line-height: 1.55; }
.article pre code { background: none; color: inherit; padding: 0; font-size: 15px; }
.copy-btn {
  position: absolute; top: 12px; right: 12px;
  background: var(--bg-elev); border: 1px solid var(--border);
  color: var(--text-secondary); border-radius: 8px; padding: 4px 10px;
  font-size: 12px; cursor: pointer; transition: all 0.2s ease;
}
.copy-btn:hover { background: var(--bg-subtle); }

/* Share bar */
.share-bar { display: flex; gap: 10px; align-items: center; margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--border); flex-wrap: wrap; }
.share-bar span { font-size: 14px; color: var(--text-secondary); }
.share-btn { background: var(--bg-subtle); border: none; color: var(--text); border-radius: 980px; padding: 8px 16px; font-size: 14px; font-weight: 600; cursor: pointer; transition: all 0.2s ease; }
.share-btn:hover { background: var(--accent); color: #fff; }

/* Prev / next */
.pn { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 40px; }
.pn a { display: block; background: var(--bg-subtle); border-radius: 18px; padding: 20px; text-decoration: none; color: var(--text); transition: transform 0.25s ease, background 0.25s ease; }
.pn a:hover { transform: translateY(-2px); background: var(--bg-elev); }
.pn .dir { font-size: 12px; color: var(--text-tertiary); display: block; margin-bottom: 6px; }
.pn .t { font-size: 16px; font-weight: 600; }
.pn a.next { text-align: right; }

/* TOC */
.toc { background: var(--bg-subtle); border-radius: 16px; padding: 20px 24px; margin: 32px 0; font-size: 15px; }
.toc strong { display: block; margin-bottom: 10px; font-size: 14px; color: var(--text-secondary); }
.toc a { display: block; color: var(--text-secondary); padding: 3px 0; }
.toc a:hover { color: var(--accent); }
.toc .l2 { padding-left: 16px; }

/* ---------- Archive ---------- */
.archive-list h2 { font-size: 28px; font-weight: 700; margin: 44px 0 12px; }
.archive-list ul { list-style: none; }
.archive-list li { border-bottom: 1px solid var(--border); }
.archive-list a { display: flex; justify-content: space-between; align-items: center; gap: 20px; padding: 14px 4px; color: var(--text); transition: color 0.2s ease; }
.archive-list a:hover { color: var(--accent); }
.archive-list .date { font-size: 13px; color: var(--text-tertiary); flex-shrink: 0; }

/* ---------- Search overlay ---------- */
.search-overlay {
  position: fixed; inset: 0; z-index: 300;
  background: color-mix(in srgb, var(--bg) 60%, transparent);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  display: none; align-items: flex-start; justify-content: center;
  padding: 12vh 20px 0;
}
.search-overlay.open { display: flex; }
.search-box { width: 100%; max-width: 560px; }
.search-input {
  width: 100%; font-size: 22px; padding: 18px 22px;
  border: 1px solid var(--border); border-radius: 16px;
  background: var(--bg-elev); color: var(--text);
  outline: none; box-shadow: var(--shadow-card);
}
.search-results { margin-top: 12px; max-height: 55vh; overflow-y: auto; background: var(--bg-elev); border-radius: 16px; box-shadow: var(--shadow-card); border: 1px solid var(--border); }
.search-results a { display: block; padding: 14px 20px; color: var(--text); border-bottom: 1px solid var(--border); }
.search-results a:last-child { border-bottom: none; }
.search-results a:hover { background: var(--bg-subtle); }
.search-results .t { font-weight: 600; }
.search-results .m { font-size: 13px; color: var(--text-tertiary); }
.empty { padding: 24px 20px; color: var(--text-tertiary); text-align: center; }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--border); padding: 48px 0; text-align: center; color: var(--text-tertiary); font-size: 13px; }
.footer a { color: var(--text-secondary); }
.footer a:hover { color: var(--text); }

/* ---------- Reveal ---------- */
html.js .reveal { opacity: 0; transform: translateY(22px); transition: opacity .7s cubic-bezier(.4,0,.2,1), transform .7s cubic-bezier(.4,0,.2,1); }
html.js .reveal.visible { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  .container { padding: 0 20px; }
  .nav-inner { padding: 10px 20px; }
  .hero { padding: 64px 0 40px; }
  .nav-links a { padding: 8px 9px; font-size: 14px; }
  .pn { grid-template-columns: 1fr; }
  .pn a.next { text-align: left; }
}