:root {
  --bg: #0a0e14;
  --bg-elev: #131820;
  --panel: #1a212c;
  --panel-2: #232c3a;
  --text: #e8eef5;
  --text-soft: #b8c4d4;
  --muted: #6e7d92;
  --accent: #f0b90b;
  --accent-2: #f8d147;
  --accent-soft: rgba(240, 185, 11, 0.12);
  --success: #00c896;
  --danger: #f6465d;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --radius: 12px;
  --radius-sm: 8px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Roboto, sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--accent); text-decoration: none; transition: color .15s; }
a:hover { color: var(--accent-2); }

.wrap { max-width: 1100px; margin: 0 auto; padding: 0 1.25rem; }
.wrap-narrow { max-width: 760px; margin: 0 auto; padding: 0 1.25rem; }

/* ============ HEADER ============ */
.site-header {
  background: rgba(10, 14, 20, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0.9rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
}
.site-header .wrap { display: flex; align-items: center; gap: 2rem; }
.brand {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text);
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.brand::before {
  content: "";
  width: 28px; height: 28px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-radius: 6px;
  display: inline-block;
}
.site-header nav { display: flex; gap: 1.5rem; flex: 1; }
.site-header nav a { color: var(--text-soft); font-weight: 500; font-size: 0.95rem; }
.site-header nav a:hover { color: var(--text); }
.lang-switch { display: flex; gap: 0.25rem; }
.lang-switch a {
  color: var(--muted);
  padding: 0.35rem 0.7rem;
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 600;
}
.lang-switch a.active { color: var(--accent); background: var(--accent-soft); }

/* ============ HERO ============ */
.hero {
  position: relative;
  padding: 5rem 0 4rem;
  background:
    radial-gradient(ellipse at top right, rgba(240, 185, 11, 0.15), transparent 50%),
    radial-gradient(ellipse at bottom left, rgba(0, 200, 150, 0.08), transparent 50%);
  border-bottom: 1px solid var(--border);
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: linear-gradient(var(--border) 1px, transparent 1px), linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 60px 60px;
  opacity: 0.4;
  mask-image: radial-gradient(ellipse at center, black 30%, transparent 70%);
}
.hero > .wrap { position: relative; }
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1.15;
  margin: 0 0 1.25rem;
  font-weight: 800;
  letter-spacing: -0.025em;
  background: linear-gradient(135deg, #fff 0%, #b8c4d4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  max-width: 850px;
}
.hero .lead {
  color: var(--text-soft);
  font-size: 1.15rem;
  max-width: 700px;
  margin: 0 0 2rem;
}
.hero-stats {
  display: flex;
  gap: 2.5rem;
  margin-top: 3rem;
  flex-wrap: wrap;
}
.hero-stats .stat { display: flex; flex-direction: column; gap: 0.25rem; }
.hero-stats .num {
  font-size: 1.75rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-stats .lbl { color: var(--muted); font-size: 0.85rem; text-transform: uppercase; letter-spacing: 0.05em; }

/* ============ CTA ============ */
.cta, .cta-primary {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #0a0e14 !important;
  padding: 0.9rem 1.75rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 1rem;
  text-decoration: none !important;
  box-shadow: 0 4px 20px rgba(240, 185, 11, 0.3);
  transition: transform .15s, box-shadow .15s;
}
.cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 24px rgba(240, 185, 11, 0.4);
}
.cta::after { content: "→"; font-size: 1.1em; }

.cta-ghost {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: transparent;
  color: var(--text);
  padding: 0.9rem 1.5rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-weight: 600;
  text-decoration: none;
}
.cta-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* Discount badge */
.discount-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: linear-gradient(135deg, rgba(0, 200, 150, 0.2), rgba(0, 200, 150, 0.05));
  border: 1px solid rgba(0, 200, 150, 0.4);
  color: #5eead4;
  padding: 0.5rem 0.9rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}
.discount-badge::before {
  content: "★";
  color: var(--success);
  font-size: 1em;
}
.discount-inline {
  display: inline-block;
  background: var(--accent-soft);
  color: var(--accent);
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8em;
  font-weight: 700;
  margin-left: 0.4rem;
  vertical-align: middle;
}

/* Top promo bar */
.promo-bar {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  color: #0a0e14;
  text-align: center;
  padding: 0.5rem 1rem;
  font-size: 0.85rem;
  font-weight: 600;
}
.promo-bar a {
  color: #0a0e14;
  text-decoration: underline;
  margin-left: 0.5rem;
}
.promo-bar a:hover { color: #0a0e14; }

/* CTA box benefit list */
.cta-box ul.benefits {
  list-style: none;
  padding: 0;
  margin: 0 0 1.5rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem 1.5rem;
  text-align: left;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}
.cta-box ul.benefits li {
  color: var(--text-soft);
  font-size: 0.95rem;
  position: relative;
  padding-left: 1.5rem;
}
.cta-box ul.benefits li::before {
  content: "✓";
  color: var(--success);
  position: absolute;
  left: 0;
  font-weight: 700;
}

/* ============ FEATURE CARDS ============ */
.section { padding: 4rem 0; }
.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin: 0 0 0.5rem;
  letter-spacing: -0.02em;
}
.section-sub { color: var(--muted); margin: 0 0 2rem; }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
}
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  transition: transform .15s, border-color .15s;
}
.card:hover { transform: translateY(-2px); border-color: var(--border-strong); }
.card .icon {
  width: 44px; height: 44px;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1rem;
}
.card h3 { margin: 0 0 0.5rem; font-size: 1.15rem; }
.card p { color: var(--text-soft); margin: 0; font-size: 0.95rem; }

/* ============ ARTICLE LIST ============ */
.article-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
  list-style: none;
  padding: 0;
}
.article-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform .15s, border-color .15s;
  display: flex;
  flex-direction: column;
}
.article-card:hover { transform: translateY(-3px); border-color: var(--border-strong); }
.article-card a { color: var(--text); text-decoration: none; display: flex; flex-direction: column; height: 100%; }
.article-card .cover {
  aspect-ratio: 16 / 9;
  width: 100%;
  background: var(--panel-2);
  background-size: cover;
  background-position: center;
}
.article-card .cover.placeholder {
  background: linear-gradient(135deg, var(--panel-2), var(--panel));
  display: flex; align-items: center; justify-content: center;
  color: var(--muted);
  font-size: 2rem;
}
.article-card .body { padding: 1.25rem; flex: 1; display: flex; flex-direction: column; }
.article-card .tag {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  margin-bottom: 0.75rem;
  align-self: flex-start;
}
.article-card h3 { margin: 0 0 0.5rem; font-size: 1.1rem; line-height: 1.4; font-weight: 700; }
.article-card p { color: var(--text-soft); margin: 0 0 1rem; font-size: 0.9rem; flex: 1; }
.article-card .meta { color: var(--muted); font-size: 0.8rem; display: flex; gap: 0.75rem; }

/* ============ ARTICLE PAGE ============ */
.post-hero {
  position: relative;
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--border);
}
.post-hero .tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.3rem 0.75rem;
  border-radius: 4px;
  margin-bottom: 1rem;
}
.post-hero h1 {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  line-height: 1.25;
  margin: 0 0 1rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  max-width: 900px;
}
.post-hero .meta {
  color: var(--muted);
  font-size: 0.9rem;
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  align-items: center;
}
.post-hero .meta .author {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-soft);
}
.post-hero .meta .author::before {
  content: "";
  display: inline-block;
  width: 28px; height: 28px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
}

.cover-image {
  width: 100%;
  aspect-ratio: 16 / 8;
  object-fit: cover;
  border-radius: var(--radius);
  margin: 1.5rem 0;
  border: 1px solid var(--border);
}
.cover-image-credit {
  font-size: 0.75rem;
  color: var(--muted);
  text-align: right;
  margin-top: -1rem;
  margin-bottom: 1.5rem;
}

/* TOC */
.post-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2rem;
  padding-top: 2rem;
}
@media (min-width: 1024px) {
  .post-layout { grid-template-columns: minmax(0, 1fr) 240px; }
}
.toc {
  position: sticky;
  top: 80px;
  align-self: flex-start;
  font-size: 0.85rem;
  color: var(--text-soft);
  border-left: 2px solid var(--border);
  padding-left: 1rem;
  display: none;
}
@media (min-width: 1024px) { .toc { display: block; } }
.toc h4 { color: var(--muted); font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.05em; margin: 0 0 0.75rem; }
.toc ul { list-style: none; padding: 0; margin: 0; }
.toc li { margin: 0.4rem 0; }
.toc a { color: var(--text-soft); }
.toc a:hover { color: var(--accent); }

/* Prose */
.prose {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-soft);
  max-width: 760px;
}
.prose h2 {
  margin: 2.5rem 0 1rem;
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.015em;
  scroll-margin-top: 80px;
}
.prose h3 {
  margin: 2rem 0 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  scroll-margin-top: 80px;
}
.prose p { margin: 0 0 1.25rem; }
.prose strong { color: var(--text); font-weight: 700; }
.prose ul, .prose ol { padding-left: 1.5rem; margin: 0 0 1.25rem; }
.prose li { margin: 0.5rem 0; }
.prose code {
  background: var(--panel);
  color: var(--accent);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-size: 0.9em;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}
.prose pre {
  background: var(--panel);
  padding: 1.25rem;
  border-radius: var(--radius-sm);
  overflow-x: auto;
  border: 1px solid var(--border);
  margin: 1.5rem 0;
}
.prose pre code { background: none; color: var(--text-soft); padding: 0; }
.prose blockquote {
  border-left: 3px solid var(--accent);
  padding: 0.75rem 0 0.75rem 1.25rem;
  color: var(--text);
  background: var(--accent-soft);
  margin: 1.5rem 0;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
.prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  background: var(--panel);
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border);
}
.prose th, .prose td {
  padding: 0.85rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--border);
}
.prose th {
  background: var(--panel-2);
  font-weight: 700;
  color: var(--text);
  font-size: 0.95rem;
}
.prose tr:last-child td { border-bottom: none; }

/* Mermaid container */
.prose .mermaid {
  background: var(--panel);
  padding: 1.5rem;
  border-radius: var(--radius-sm);
  margin: 1.5rem 0;
  text-align: center;
  border: 1px solid var(--border);
}

/* Callouts */
.callout {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  margin: 1.5rem 0;
  border-left: 4px solid;
}
.callout-info { background: rgba(0, 132, 255, 0.08); border-color: #0084ff; }
.callout-warn { background: rgba(246, 70, 93, 0.08); border-color: var(--danger); }
.callout-tip  { background: rgba(0, 200, 150, 0.08); border-color: var(--success); }

/* CTA box in articles */
.cta-box {
  margin: 3rem 0 1.5rem;
  background: linear-gradient(135deg, var(--panel) 0%, var(--panel-2) 100%);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.cta-box::before {
  content: "";
  position: absolute; inset: 0;
  background: radial-gradient(ellipse at top, var(--accent-soft), transparent 60%);
  pointer-events: none;
}
.cta-box > * { position: relative; }
.cta-box h3 { margin: 0 0 0.5rem; font-size: 1.4rem; }
.cta-box p { color: var(--text-soft); margin: 0 0 1.5rem; }

/* Related */
.related {
  margin: 3rem 0 1rem;
  padding: 1.5rem;
  background: var(--panel);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.related h3 { margin: 0 0 1rem; font-size: 1.1rem; color: var(--text); }
.related ul { list-style: none; padding: 0; margin: 0; }
.related li { margin: 0.5rem 0; }
.related a { color: var(--text-soft); }
.related a:hover { color: var(--accent); }

/* ============ FOOTER ============ */
.site-footer {
  background: var(--bg-elev);
  border-top: 1px solid var(--border);
  padding: 3rem 0 2rem;
  margin-top: 4rem;
  color: var(--muted);
}
.site-footer .wrap > p { margin: 0.5rem 0; font-size: 0.9rem; }
.site-footer .disclaimer { font-size: 0.8rem; color: var(--muted); max-width: 600px; }

/* ============ RESPONSIVE ============ */
@media (max-width: 720px) {
  .site-header .wrap { gap: 1rem; }
  .site-header nav { display: none; }
  .hero { padding: 3rem 0 2.5rem; }
  .hero-stats { gap: 1.5rem; }
  .section { padding: 2.5rem 0; }
}