/* ============================================================
   成都通通电气 - 全局样式
   气质：工程蓝图 · 精密仪器 · 焊盘琥珀
============================================================ */

/* ---------- Design Tokens ---------- */
:root {
  --bg-paper: #F5F2EA;
  --bg-card: #FFFFFF;
  --bg-ink: #0F1418;
  --bg-ink-2: #1A1F24;

  --brand: #B8823A;
  --brand-deep: #8A5F26;
  --brand-soft: rgba(184, 130, 58, 0.08);

  --accent-green: #2E5D3E;
  --alert: #C0392B;

  --text-main: #1C2126;
  --text-sub: #5C6470;
  --text-mute: #8A8F97;
  --text-invert: #E8E4D8;

  --border: #D8D2C4;
  --border-strong: #B8B0A0;

  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --dur: 240ms;

  --max-w: 1200px;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Noto Sans SC', 'Inter', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-weight: 400;
  color: var(--text-main);
  background: var(--bg-paper);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  font-feature-settings: 'kern' 1, 'liga' 1;
  /* 工程坐标纸底纹 */
  background-image:
    linear-gradient(to right, rgba(28, 33, 38, 0.035) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(28, 33, 38, 0.035) 1px, transparent 1px);
  background-size: 24px 24px;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; transition: color var(--dur) var(--ease); }
button { font-family: inherit; cursor: pointer; }

.mono, .num {
  font-family: 'JetBrains Mono', 'SFMono-Regular', ui-monospace, Menlo, Consolas, monospace;
  font-feature-settings: 'tnum' 1;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- 顶部导航 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(245, 242, 234, 0.92);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand-mark {
  width: 36px;
  height: 36px;
  border: 1.5px solid var(--text-main);
  position: relative;
  display: grid;
  place-items: center;
  background: var(--bg-card);
}
.brand-mark::before, .brand-mark::after {
  content: '';
  position: absolute;
  background: var(--brand);
}
.brand-mark::before { width: 14px; height: 1.5px; }
.brand-mark::after  { width: 1.5px; height: 14px; }
.brand-mark .dot {
  width: 5px; height: 5px; background: var(--brand); border-radius: 50%;
  z-index: 1;
}
.brand-text {
  display: flex; flex-direction: column; line-height: 1.15;
}
.brand-text .cn { font-weight: 700; font-size: 16px; letter-spacing: 0.02em; }
.brand-text .en {
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px;
  color: var(--text-sub);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  gap: 4px;
  align-items: center;
}
.nav-links a {
  padding: 8px 14px;
  font-size: 14px;
  color: var(--text-sub);
  border: 1px solid transparent;
  transition: all var(--dur) var(--ease);
  position: relative;
}
.nav-links a:hover {
  color: var(--text-main);
  border-color: var(--border);
}
.nav-links a.active {
  color: var(--text-main);
  background: var(--bg-card);
  border-color: var(--border);
}
.nav-links a.active::before {
  content: '';
  position: absolute;
  left: 8px; right: 8px;
  bottom: -1px;
  height: 2px;
  background: var(--brand);
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  background: var(--bg-ink);
  color: var(--text-invert);
  font-size: 13px;
  letter-spacing: 0.06em;
  border: 1px solid var(--bg-ink);
  transition: background var(--dur) var(--ease);
}
.nav-cta:hover { background: var(--brand-deep); border-color: var(--brand-deep); }

.nav-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border);
  width: 42px; height: 42px;
  align-items: center; justify-content: center;
}
.nav-toggle span { display: block; width: 18px; height: 1.5px; background: var(--text-main); position: relative; }
.nav-toggle span::before, .nav-toggle span::after {
  content: ''; position: absolute; left: 0; width: 18px; height: 1.5px; background: var(--text-main);
}
.nav-toggle span::before { top: -6px; }
.nav-toggle span::after { top: 6px; }

/* ---------- 通用区块 ---------- */
section { padding: 96px 0; position: relative; }
.section-tag {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px;
  color: var(--brand);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  margin-bottom: 20px;
}
.section-tag::before {
  content: ''; width: 24px; height: 3px; background: var(--brand);
}
.section-title {
  font-size: clamp(28px, 4vw, 44px);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 0 0 16px;
  color: var(--text-main);
}
.section-subtitle {
  font-size: 16px;
  color: var(--text-sub);
  max-width: 640px;
  margin: 0;
}
.section-head {
  display: flex; justify-content: space-between; align-items: flex-end;
  gap: 32px; margin-bottom: 56px; flex-wrap: wrap;
}
.section-index {
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px; color: var(--text-mute);
  letter-spacing: 0.16em;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  font-size: 14px;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  transition: all var(--dur) var(--ease);
  cursor: pointer;
}
.btn-primary {
  background: var(--bg-ink);
  color: var(--text-invert);
  border-color: var(--bg-ink);
}
.btn-primary:hover { background: var(--brand-deep); border-color: var(--brand-deep); }

.btn-ghost {
  background: transparent;
  color: var(--text-main);
  border-color: var(--border-strong);
}
.btn-ghost:hover { border-color: var(--text-main); background: var(--bg-card); }

.btn-arrow { width: 14px; height: 10px; position: relative; }
.btn-arrow::before, .btn-arrow::after {
  content: ''; position: absolute; background: currentColor;
}
.btn-arrow::before { top: 50%; left: 0; width: 14px; height: 1.5px; transform: translateY(-50%); }
.btn-arrow::after {
  right: 0; top: 50%; width: 7px; height: 7px;
  border-top: 1.5px solid currentColor; border-right: 1.5px solid currentColor;
  transform: translateY(-50%) rotate(45deg);
  background: transparent;
}

/* ---------- 卡片 ---------- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  padding: 32px;
  transition: border-color var(--dur) var(--ease);
  position: relative;
}
.card::before {
  content: '';
  position: absolute; top: -1px; left: -1px;
  width: 12px; height: 12px;
  border-top: 1.5px solid transparent;
  border-left: 1.5px solid transparent;
  transition: border-color var(--dur) var(--ease);
}
.card:hover { border-color: var(--brand); }
.card:hover::before { border-color: var(--brand); }

/* 索引编号 */
.card-index {
  font-family: 'JetBrains Mono', monospace;
  font-size: 11px;
  color: var(--text-mute);
  letter-spacing: 0.18em;
  margin-bottom: 20px;
}

/* ---------- Grid Helpers ---------- */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* ---------- Reveal 动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 500ms var(--ease), transform 500ms var(--ease);
}
.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Footer ---------- */
.site-footer {
  background: var(--bg-ink);
  color: var(--text-invert);
  padding: 72px 0 32px;
  border-top: 4px solid var(--brand);
}
.site-footer .container { max-width: var(--max-w); }
.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: 48px;
  margin-bottom: 56px;
}
.footer-brand .brand-mark { background: transparent; border-color: var(--text-invert); }
.footer-brand .brand-mark::before, .footer-brand .brand-mark::after { background: var(--brand); }
.footer-brand .brand-text .cn { color: var(--text-invert); }
.footer-brand .brand-text .en { color: var(--text-mute); }
.footer-brand p {
  color: var(--text-mute);
  font-size: 13px;
  margin: 20px 0 0;
  line-height: 1.8;
  max-width: 300px;
}
.footer-col h4 {
  color: var(--text-invert);
  font-size: 12px;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  margin: 0 0 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
}
.footer-col ul { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 10px; }
.footer-col a { color: var(--text-mute); font-size: 13px; transition: color var(--dur) var(--ease); }
.footer-col a:hover { color: var(--brand); }
.footer-col p { color: var(--text-mute); font-size: 13px; margin: 0 0 10px; line-height: 1.7; }
.footer-col .mono { color: var(--text-invert); font-size: 14px; }

.footer-bottom {
  display: flex; justify-content: space-between; align-items: center;
  padding-top: 28px;
  border-top: 1px solid rgba(255,255,255,0.08);
  font-size: 12px;
  color: var(--text-mute);
  font-family: 'JetBrains Mono', monospace;
  letter-spacing: 0.06em;
}

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  section { padding: 72px 0; }
}
@media (max-width: 768px) {
  .nav-links, .nav-cta { display: none; }
  .nav-toggle { display: inline-flex; }
  .site-header.open .nav-links {
    display: flex;
    position: absolute;
    top: 72px; left: 0; right: 0;
    background: var(--bg-card);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px 24px;
    gap: 0;
  }
  .site-header.open .nav-links a {
    padding: 14px 8px;
    border-bottom: 1px solid var(--border);
    width: 100%;
  }
  .site-header.open .nav-links a.active::before { display: none; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
  .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }
  section { padding: 56px 0; }
  .section-head { flex-direction: column; align-items: flex-start; }
}