/* ============================================================
   南京洲丽达机械科技 · 全站样式 main.css
   T1 首页基础版（T2 任务将精修并抽取复用组件）
   ============================================================ */

/* ------------------- 1. 设计令牌 ------------------- */
:root {
  /* 配色 */
  --c-bg:        #0B1524;   /* 主背景 */
  --c-bg-2:      #0E1A2E;   /* 次级背景 */
  --c-card:      #12203A;   /* 卡片背景 */
  --c-card-2:    #16294A;   /* 卡片次级 */
  --c-border:    #1E3252;   /* 边框 */
  --c-text:      #FFFFFF;   /* 主文字 */
  --c-text-sub:  #8FA3BF;   /* 副文字 */
  --c-text-mute:#5C6E8A;   /* 弱文字 */
  --c-accent:    #FF6B1A;   /* 强调橙 */
  --c-accent-2:  #FF8A4A;   /* 强调橙亮 */
  --c-accent-d:  #C9510F;   /* 强调橙暗 */

  /* 字体 */
  --ff-sans: "Noto Sans SC", "思源黑体", "Source Han Sans SC",
             "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;

  /* 圆角 */
  --r-card: 12px;
  --r-btn:  6px;
  --r-pill: 999px;

  /* 节奏 */
  --maxw: 1200px;
  --gutter: 24px;

  /* 动效 */
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur: 300ms;

  /* 阴影 */
  --shadow-card: 0 8px 24px rgba(0,0,0,.35);
  --shadow-pop: 0 18px 60px rgba(0,0,0,.45);
}

/* ------------------- 2. 重置 ------------------- */
*,*::before,*::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--ff-sans);
  font-size: 16px;
  line-height: 1.8;
  color: var(--c-text);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}
img,svg,video { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; transition: color var(--dur) var(--ease); }
a:hover { color: var(--c-accent-2); }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
ul,ol { margin: 0; padding: 0; list-style: none; }
h1,h2,h3,h4,h5,h6 { margin: 0; font-weight: 700; line-height: 1.25; }
p { margin: 0; }

/* ------------------- 3. 布局容器 ------------------- */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
}
section { position: relative; }

/* ------------------- 4. 按钮 ------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: var(--r-btn);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: .02em;
  transition: all var(--dur) var(--ease);
  white-space: nowrap;
  border: 1px solid transparent;
}
.btn-lg { padding: 16px 36px; font-size: 16px; }
.btn-primary {
  background: linear-gradient(135deg, var(--c-accent), var(--c-accent-d));
  color: #fff;
  box-shadow: 0 6px 18px rgba(255,107,26,.25);
}
.btn-primary:hover {
  background: linear-gradient(135deg, var(--c-accent-2), var(--c-accent));
  color: #fff;
  transform: translateY(-2px);
  box-shadow: 0 10px 26px rgba(255,107,26,.4);
}
.btn-ghost {
  color: var(--c-text);
  border-color: var(--c-border);
  background: rgba(255,255,255,.02);
}
.btn-ghost:hover {
  color: var(--c-accent-2);
  border-color: var(--c-accent);
  background: rgba(255,107,26,.08);
}

/* ------------------- 5. 章节通用 ------------------- */
.section-head {
  max-width: 760px;
  margin: 0 auto 56px;
  text-align: center;
}
.section-eyebrow {
  display: inline-block;
  font-size: 12px;
  letter-spacing: .25em;
  color: var(--c-accent);
  font-weight: 500;
  margin-bottom: 14px;
}
.section-title {
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  margin-bottom: 16px;
}
.section-desc {
  color: var(--c-text-sub);
  font-size: 16px;
}
.section-foot {
  text-align: center;
  margin-top: 48px;
}

/* ------------------- 6. 顶部导航 ------------------- */
.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 100;
  background: rgba(11, 21, 36, .55);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid transparent;
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.site-header.is-scrolled {
  background: rgba(11, 21, 36, .92);
  border-bottom-color: var(--c-border);
}
.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}
.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px; height: 40px;
  border-radius: var(--r-btn);
  background: linear-gradient(135deg, var(--c-accent), var(--c-accent-d));
  color: #fff;
  font-weight: 900;
  font-size: 14px;
  letter-spacing: .04em;
}
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-cn { font-size: 16px; font-weight: 700; color: var(--c-text); }
.brand-en { font-size: 10px; letter-spacing: .18em; color: var(--c-text-sub); }

.nav-menu { display: flex; align-items: center; gap: 4px; }
.nav-link {
  padding: 10px 16px;
  font-size: 15px;
  color: var(--c-text-sub);
  border-radius: var(--r-btn);
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.nav-link:hover { color: var(--c-text); background: rgba(255,255,255,.04); }
.nav-link.active { color: var(--c-text); }
.nav-link.active::after {
  content: "";
  display: block;
  width: 18px; height: 2px;
  margin: 4px auto 0;
  background: var(--c-accent);
  border-radius: 2px;
}
.nav-cta {
  background: var(--c-accent);
  color: #fff;
  padding: 10px 20px;
}
.nav-cta:hover { background: var(--c-accent-2); color: #fff; }

.nav-toggle {
  display: none;
  width: 44px; height: 44px;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  border-radius: var(--r-btn);
  border: 1px solid var(--c-border);
}
.nav-toggle span {
  width: 20px; height: 2px;
  background: var(--c-text);
  border-radius: 2px;
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ------------------- 7. Hero ------------------- */
.hero {
  position: relative;
  min-height: 100svh;
  display: flex;
  align-items: center;
  padding: 120px 0 80px;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}
.hero-bg img {
  width: 100%; height: 100%;
  object-fit: cover;
  transform: scale(1.05);
  will-change: transform;
}
.hero-bg-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, rgba(11,21,36,.65) 0%, rgba(11,21,36,.85) 60%, var(--c-bg) 100%),
    radial-gradient(60% 80% at 30% 50%, rgba(255,107,26,.18), transparent 70%);
}
.hero-content {
  position: relative;
  z-index: 2;
  max-width: 860px;
}
.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--c-text-sub);
  letter-spacing: .04em;
  margin-bottom: 22px;
  padding: 8px 14px;
  background: rgba(255,255,255,.04);
  border: 1px solid var(--c-border);
  border-radius: var(--r-pill);
}
.hero-eyebrow .dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--c-accent);
  box-shadow: 0 0 12px var(--c-accent);
}
.hero-title {
  font-size: clamp(32px, 5vw, 64px);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -.01em;
  margin-bottom: 24px;
  background: linear-gradient(180deg, #fff, #C7D6EA);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-sub {
  font-size: clamp(15px, 1.8vw, 19px);
  color: var(--c-text-sub);
  line-height: 1.8;
  margin-bottom: 36px;
}
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-bottom: 40px; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 12px; }
.hero-tags li {
  padding: 6px 14px;
  font-size: 13px;
  color: var(--c-text-sub);
  border: 1px solid var(--c-border);
  border-radius: var(--r-pill);
  background: rgba(255,255,255,.02);
}
.hero-scroll {
  position: absolute;
  right: 24px; bottom: 32px;
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  color: var(--c-text-mute);
  font-size: 10px;
  letter-spacing: .25em;
}
.hero-scroll-line {
  width: 1px; height: 48px;
  background: linear-gradient(180deg, transparent, var(--c-accent));
  position: relative;
  overflow: hidden;
}
.hero-scroll-line::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, var(--c-accent), transparent);
  animation: scrollLine 2.2s var(--ease) infinite;
}
@keyframes scrollLine {
  0%   { transform: translateY(-100%); }
  100% { transform: translateY(100%);  }
}

/* ------------------- 8. 数据计数 ------------------- */
.stats {
  padding: 64px 0;
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
  background: var(--c-bg-2);
}
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}
.stat-item { padding: 16px 8px; }
.stat-num {
  display: block;
  font-size: clamp(36px, 5vw, 56px);
  font-weight: 900;
  line-height: 1;
  background: linear-gradient(180deg, var(--c-accent-2), var(--c-accent-d));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 10px;
}
.stat-label {
  font-size: 14px;
  color: var(--c-text-sub);
  letter-spacing: .04em;
}

/* ------------------- 9. 产品系列 ------------------- */
.products { padding: 96px 0; }
.product-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.product-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.product-card:hover {
  transform: translateY(-4px);
  border-color: var(--c-accent);
  box-shadow: var(--shadow-card);
}
.product-card-media {
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: var(--c-bg-2);
}
.product-card-media img {
  width: 100%; height: 100%;
  object-fit: cover;
  object-position: center 20%;
  /* 放大 104% 并向下偏移 4%，把右下角水印裁出可视区 */
  transform: scale(1.04) translateY(4%);
  transition: transform 600ms var(--ease);
}
.product-card:hover .product-card-media img {
  transform: scale(1.10) translateY(4%);
}
.product-card-body { padding: 22px 20px 24px; display: flex; flex-direction: column; gap: 8px; }
.product-tag {
  display: inline-block;
  font-size: 11px;
  letter-spacing: .2em;
  color: var(--c-accent);
  font-weight: 500;
}
.product-name { font-size: 18px; font-weight: 700; }
.product-desc { font-size: 13px; color: var(--c-text-sub); line-height: 1.7; flex: 1; }
.product-link {
  margin-top: 8px;
  font-size: 13px;
  font-weight: 500;
  color: var(--c-accent-2);
}

/* ------------------- 10. 应用行业 ------------------- */
.industries {
  padding: 96px 0;
  background: var(--c-bg-2);
  border-top: 1px solid var(--c-border);
  border-bottom: 1px solid var(--c-border);
}
.industry-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.industry-card {
  position: relative;
  border-radius: var(--r-card);
  overflow: hidden;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.industry-card:hover {
  transform: translateY(-3px);
  border-color: var(--c-accent);
}
.industry-media { aspect-ratio: 1 / 1; overflow: hidden; position: relative; }
.industry-media img {
  width: 100%; height: 100%;
  object-fit: cover;
  transition: transform 600ms var(--ease);
}
.industry-card:hover .industry-media img { transform: scale(1.08); }
.industry-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 40%, rgba(11,21,36,.92) 100%);
}
.industry-body {
  position: absolute;
  inset: auto 0 0 0;
  padding: 20px 22px;
  z-index: 2;
}
.industry-num {
  font-size: 11px;
  color: var(--c-accent);
  letter-spacing: .15em;
  font-weight: 500;
}
.industry-name {
  font-size: 22px;
  font-weight: 700;
  margin: 4px 0 6px;
}
.industry-desc {
  font-size: 13px;
  color: var(--c-text-sub);
}

/* ------------------- 11. 关于简述 ------------------- */
.about-brief { padding: 96px 0; }
.about-grid {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: 56px;
  align-items: center;
}
.about-media {
  border-radius: var(--r-card);
  overflow: hidden;
  border: 1px solid var(--c-border);
  aspect-ratio: 4 / 3;
  position: relative;
}
.about-media img { width: 100%; height: 100%; object-fit: cover; }
.about-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, transparent 60%, rgba(255,107,26,.12));
}
.about-content .section-eyebrow { margin-bottom: 14px; }
.about-content .section-title { text-align: left; margin-bottom: 18px; }
.about-lead {
  color: var(--c-text-sub);
  margin-bottom: 24px;
  line-height: 1.85;
}
.about-list { display: grid; gap: 12px; margin-bottom: 28px; }
.about-list li {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  color: var(--c-text);
  font-size: 15px;
}
.about-list .ic {
  flex: none;
  width: 18px; height: 18px;
  margin-top: 6px;
  border-radius: 50%;
  background: var(--c-accent);
  position: relative;
}
.about-list .ic::after {
  content: "";
  position: absolute;
  inset: 4px;
  background: var(--c-bg);
  border-radius: 50%;
}
.about-actions { display: flex; flex-wrap: wrap; gap: 12px; }

/* ------------------- 12. CTA ------------------- */
.cta {
  padding: 96px 0;
  background:
    radial-gradient(80% 100% at 50% 0%, rgba(255,107,26,.16), transparent 70%),
    var(--c-bg-2);
  border-top: 1px solid var(--c-border);
  text-align: center;
}
.cta-inner { max-width: 760px; margin: 0 auto; }
.cta-title {
  font-size: clamp(26px, 4vw, 40px);
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 18px;
}
.cta-desc { color: var(--c-text-sub); margin-bottom: 32px; }
.cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
  margin-bottom: 24px;
}
.cta-note {
  font-size: 13px;
  color: var(--c-text-mute);
}

/* ------------------- 13. Footer ------------------- */
.site-footer {
  background: var(--c-bg-2);
  border-top: 1px solid var(--c-border);
  padding: 64px 0 0;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 48px;
}
.footer-brand .brand { margin-bottom: 16px; }
.footer-brand .brand-mark { background: rgba(255,107,26,.15); color: var(--c-accent); }
.footer-tagline {
  color: var(--c-text-sub);
  font-size: 14px;
  margin-bottom: 16px;
}
.footer-addr {
  font-size: 13px;
  color: var(--c-text-mute);
  line-height: 1.8;
}
.footer-h {
  font-size: 14px;
  font-weight: 600;
  color: var(--c-text);
  margin-bottom: 18px;
  letter-spacing: .04em;
}
.footer-col ul { display: grid; gap: 10px; }
.footer-col a {
  color: var(--c-text-sub);
  font-size: 14px;
}
.footer-col a:hover { color: var(--c-accent-2); }
.footer-bottom {
  border-top: 1px solid var(--c-border);
  padding: 20px var(--gutter);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  font-size: 13px;
  color: var(--c-text-mute);
  flex-wrap: wrap;
}
.footer-bottom a { color: var(--c-text-sub); }
.footer-sep { margin: 0 8px; color: var(--c-text-mute); }

/* ------------------- 14. 滚动 fade-up 动效 ------------------- */
[data-fade-up] {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 700ms var(--ease), transform 700ms var(--ease);
  will-change: opacity, transform;
}
[data-fade-up].is-in {
  opacity: 1;
  transform: none;
}
/* 连续上扬 */
.product-grid [data-fade-up],
.industry-grid [data-fade-up],
.stats-grid [data-fade-up] {
  transition-delay: var(--stagger, 0ms);
}

/* ------------------- 15. 无障碍 / 动效偏好 ------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
    scroll-behavior: auto !important;
  }
  [data-fade-up] { opacity: 1; transform: none; }
  .hero-bg img { transform: none !important; }
}

/* ------------------- 16. 响应式 — 1200 以下 ------------------- */
@media (max-width: 1200px) {
  .product-grid { grid-template-columns: repeat(2, 1fr); }
}

/* ------------------- 17. 响应式 — 768 以下（手机优先回退） ------------------- */
@media (max-width: 768px) {
  :root { --gutter: 18px; }

  .nav-wrap { height: 60px; }
  .nav-menu {
    position: fixed;
    inset: 60px 0 auto 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 18px 24px;
    background: rgba(11,21,36,.98);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--c-border);
    transform: translateY(-120%);
    opacity: 0;
    pointer-events: none;
    transition: transform 380ms var(--ease), opacity 280ms var(--ease);
  }
  .nav-menu.is-open { transform: none; opacity: 1; pointer-events: auto; }
  .nav-link { padding: 14px 12px; border-bottom: 1px solid var(--c-border); border-radius: 0; }
  .nav-link.active::after { display: none; }
  .nav-cta { margin-top: 12px; text-align: center; border-bottom: 0; }
  .nav-toggle { display: flex; }

  .hero { min-height: 92svh; padding: 100px 0 60px; }
  .hero-scroll { display: none; }
  .hero-actions .btn { flex: 1; min-width: 140px; }

  .stats { padding: 48px 0; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 32px 12px; }

  .products, .industries, .about-brief, .cta { padding: 64px 0; }
  .section-head { margin-bottom: 36px; }

  .product-grid { grid-template-columns: 1fr; gap: 16px; }
  .product-card-body { padding: 18px 18px 20px; }

  .industry-grid { grid-template-columns: 1fr; gap: 14px; }

  .about-grid { grid-template-columns: 1fr; gap: 32px; }
  .about-content .section-title { text-align: left; }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 32px 20px;
    padding-bottom: 36px;
  }
  .footer-brand { grid-column: 1 / -1; }
  .footer-bottom { flex-direction: column; text-align: center; }
}

/* ------------------- 18. 响应式 — 小屏手机进一步优化 ------------------- */
@media (max-width: 420px) {
  .hero-eyebrow { font-size: 12px; padding: 6px 12px; }
  .hero-actions { flex-direction: column; }
  .hero-actions .btn { width: 100%; }
  .about-actions { flex-direction: column; }
  .about-actions .btn { width: 100%; }
  .cta-actions { flex-direction: column; }
  .cta-actions .btn { width: 100%; }
}

/* ============================================================
   19. 全站通用组件（T2 新增，供所有内页复用）
   ============================================================ */

/* ---------- 19.1 noscript 回退导航 ---------- */
.noscript-nav {
  background: var(--c-bg-2);
  border-bottom: 1px solid var(--c-border);
  padding: 10px 16px;
  font-size: 13px;
  text-align: center;
}
.noscript-nav a { color: var(--c-text-sub); margin: 0 6px; }
.noscript-nav a:hover { color: var(--c-accent-2); }

/* ---------- 19.2 内页页头（面包屑 + H1） ---------- */
.page-header {
  position: relative;
  padding: 140px 0 72px;
  background:
    linear-gradient(180deg, rgba(11,21,36,.85), rgba(11,21,36,.95)),
    radial-gradient(60% 100% at 20% 50%, rgba(255,107,26,.12), transparent 70%),
    var(--c-bg-2);
  border-bottom: 1px solid var(--c-border);
  overflow: hidden;
}
.page-header::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,107,26,.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,107,26,.04) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
}
.page-header .container { position: relative; z-index: 2; }
.page-header h1 {
  font-size: clamp(28px, 4.5vw, 48px);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 12px;
  background: linear-gradient(180deg, #fff, #C7D6EA);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.page-header .page-desc {
  color: var(--c-text-sub);
  font-size: clamp(14px, 1.6vw, 17px);
  max-width: 640px;
  line-height: 1.8;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--c-text-mute);
  margin-bottom: 20px;
}
.breadcrumb a { color: var(--c-text-sub); }
.breadcrumb a:hover { color: var(--c-accent-2); }
.breadcrumb .sep { color: var(--c-text-mute); }
.breadcrumb .current { color: var(--c-text); }

/* ---------- 19.3 内页主内容区 ---------- */
.page-body { padding: 64px 0 80px; }

/* 两栏布局（侧边栏 + 内容） */
.layout-sidebar {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 40px;
  align-items: start;
}

/* 侧边栏导航 */
.sidebar {
  position: sticky;
  top: 96px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  padding: 8px;
}
.sidebar-h {
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--c-accent);
  padding: 12px 14px 8px;
}
.sidebar a {
  display: block;
  padding: 10px 14px;
  font-size: 14px;
  color: var(--c-text-sub);
  border-radius: var(--r-btn);
  transition: all var(--dur) var(--ease);
}
.sidebar a:hover { color: var(--c-text); background: rgba(255,255,255,.04); }
.sidebar a.is-active { color: #fff; background: var(--c-accent); }
.sidebar a.is-active:hover { color: #fff; background: var(--c-accent-2); }

/* 文章内容排版 */
.prose { color: var(--c-text-sub); line-height: 1.9; font-size: 16px; }
.prose h2 {
  font-size: clamp(22px, 3vw, 30px);
  color: var(--c-text);
  font-weight: 700;
  margin: 48px 0 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--c-border);
}
.prose h3 {
  font-size: 20px;
  color: var(--c-text);
  font-weight: 600;
  margin: 32px 0 12px;
}
.prose h4 {
  font-size: 16px;
  color: var(--c-text);
  font-weight: 600;
  margin: 24px 0 8px;
}
.prose p { margin: 0 0 16px; }
.prose ul, .prose ol { margin: 0 0 16px; padding-left: 22px; }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: 6px; }
.prose strong { color: var(--c-text); font-weight: 600; }
.prose a { color: var(--c-accent-2); text-decoration: underline; text-underline-offset: 3px; }
.prose blockquote {
  margin: 20px 0;
  padding: 16px 20px;
  background: rgba(255,107,26,.06);
  border-left: 3px solid var(--c-accent);
  border-radius: 0 var(--r-btn) var(--r-btn) 0;
  color: var(--c-text);
}
.prose img { border-radius: var(--r-card); margin: 20px 0; }

/* ---------- 19.4 表格 ---------- */
.table-wrap {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: var(--r-card);
  border: 1px solid var(--c-border);
  margin: 16px 0;
}
.table-wrap table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  min-width: 520px;
}
.table-wrap thead th {
  background: var(--c-card-2);
  color: var(--c-text);
  font-weight: 600;
  text-align: left;
  padding: 14px 16px;
  border-bottom: 1px solid var(--c-border);
  white-space: nowrap;
}
.table-wrap tbody td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--c-border);
  color: var(--c-text-sub);
}
.table-wrap tbody tr:last-child td { border-bottom: 0; }
.table-wrap tbody tr:hover { background: rgba(255,255,255,.02); }
.table-wrap .num { font-variant-numeric: tabular-nums; text-align: right; }
.table-wrap .hl { color: var(--c-accent-2); font-weight: 600; }

/* ---------- 19.5 表单 ---------- */
.form-card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  padding: 32px;
}
.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}
.form-grid .full { grid-column: 1 / -1; }
.form-field { display: flex; flex-direction: column; gap: 8px; }
.form-field label {
  font-size: 14px;
  font-weight: 500;
  color: var(--c-text);
}
.form-field label .req { color: var(--c-accent); margin-left: 4px; }
.form-field input,
.form-field textarea,
.form-field select {
  width: 100%;
  padding: 12px 14px;
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--r-btn);
  color: var(--c-text);
  font-family: inherit;
  font-size: 15px;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.form-field textarea { resize: vertical; min-height: 120px; }
.form-field input::placeholder,
.form-field textarea::placeholder { color: var(--c-text-mute); }
.form-field input:focus,
.form-field textarea:focus,
.form-field select:focus {
  outline: none;
  border-color: var(--c-accent);
  box-shadow: 0 0 0 3px rgba(255,107,26,.15);
}
.form-field input.is-error,
.form-field textarea.is-error,
.form-field select.is-error {
  border-color: #ff4d4f;
  box-shadow: 0 0 0 3px rgba(255,77,79,.12);
}
.form-field .hint { font-size: 12px; color: var(--c-text-mute); }
.form-message {
  margin-top: 16px;
  padding: 12px 16px;
  border-radius: var(--r-btn);
  font-size: 14px;
  display: none;
}
.form-message.form-message--error {
  display: block;
  background: rgba(255,77,79,.1);
  border: 1px solid rgba(255,77,79,.3);
  color: #ff8a8c;
}
.form-message.form-message--success {
  display: block;
  background: rgba(82,196,26,.1);
  border: 1px solid rgba(82,196,26,.3);
  color: #95de64;
}
.form-message.form-message--loading {
  display: block;
  background: rgba(255,107,26,.08);
  border: 1px solid rgba(255,107,26,.25);
  color: var(--c-accent-2);
}

/* ---------- 19.6 标签 / 徽章 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 12px;
  font-size: 12px;
  color: var(--c-accent-2);
  background: rgba(255,107,26,.1);
  border: 1px solid rgba(255,107,26,.25);
  border-radius: var(--r-pill);
  line-height: 1.6;
}
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 10px;
  font-size: 11px;
  font-weight: 600;
  border-radius: var(--r-pill);
}
.badge--accent { color: #fff; background: var(--c-accent); }
.badge--muted  { color: var(--c-text-sub); background: var(--c-card-2); }

/* ---------- 19.7 提示框 ---------- */
.alert {
  padding: 14px 18px;
  border-radius: var(--r-btn);
  border: 1px solid var(--c-border);
  margin: 16px 0;
  font-size: 14px;
  line-height: 1.7;
}
.alert--info    { background: rgba(24,144,255,.08); border-color: rgba(24,144,255,.3); color: #69c0ff; }
.alert--warn    { background: rgba(250,173,20,.08); border-color: rgba(250,173,20,.3); color: #ffc53d; }
.alert--danger  { background: rgba(255,77,79,.08);  border-color: rgba(255,77,79,.3);  color: #ff8a8c; }

/* ---------- 19.8 代码块（公式） ---------- */
pre {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: var(--r-btn);
  padding: 16px 18px;
  overflow-x: auto;
  margin: 16px 0;
  font-size: 14px;
  line-height: 1.7;
}
code {
  font-family: "JetBrains Mono", "Fira Code", Consolas, monospace;
  color: var(--c-accent-2);
  background: rgba(255,107,26,.08);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: .9em;
}
pre code {
  background: none;
  padding: 0;
  color: var(--c-text);
}
.formula {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-left: 3px solid var(--c-accent);
  border-radius: 0 var(--r-btn) var(--r-btn) 0;
  padding: 16px 20px;
  margin: 16px 0;
  font-family: "JetBrains Mono", "Fira Code", Consolas, monospace;
  font-size: 16px;
  color: var(--c-text);
  overflow-x: auto;
}

/* ---------- 19.9 分页 ---------- */
.pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin: 40px 0 0;
}
.pagination a, .pagination span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 38px;
  height: 38px;
  padding: 0 12px;
  border-radius: var(--r-btn);
  font-size: 14px;
  color: var(--c-text-sub);
  border: 1px solid var(--c-border);
  background: var(--c-card);
  transition: all var(--dur) var(--ease);
}
.pagination a:hover { color: var(--c-text); border-color: var(--c-accent); }
.pagination .current {
  color: #fff;
  background: var(--c-accent);
  border-color: var(--c-accent);
}
.pagination .disabled { opacity: .4; pointer-events: none; }

/* ---------- 19.10 选项卡 ---------- */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  border-bottom: 1px solid var(--c-border);
  margin-bottom: 24px;
}
.tab-btn {
  padding: 10px 18px;
  font-size: 14px;
  color: var(--c-text-sub);
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  transition: all var(--dur) var(--ease);
  background: none;
  border-top: 0; border-left: 0; border-right: 0;
}
.tab-btn:hover { color: var(--c-text); }
.tab-btn.is-active {
  color: var(--c-accent-2);
  border-bottom-color: var(--c-accent);
}
.tab-panel { display: none; }
.tab-panel.is-active { display: block; }

/* ---------- 19.11 步骤 / 时间线 ---------- */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  counter-reset: step;
}
.step {
  position: relative;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  padding: 24px 20px 20px;
}
.step::before {
  counter-increment: step;
  content: counter(step, decimal-leading-zero);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px; height: 36px;
  background: var(--c-accent);
  color: #fff;
  border-radius: 50%;
  font-weight: 700;
  font-size: 13px;
  margin-bottom: 14px;
}
.step h4 { font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.step p { font-size: 13px; color: var(--c-text-sub); line-height: 1.7; }

/* ---------- 19.12 产品参数网格 ---------- */
.spec-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 12px;
  margin: 16px 0;
}
.spec-item {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-btn);
  padding: 14px 16px;
}
.spec-item .spec-k {
  font-size: 12px;
  color: var(--c-text-mute);
  letter-spacing: .04em;
  margin-bottom: 4px;
}
.spec-item .spec-v {
  font-size: 18px;
  font-weight: 700;
  color: var(--c-text);
}
.spec-item .spec-u {
  font-size: 12px;
  color: var(--c-text-sub);
  margin-left: 2px;
}

/* ---------- 19.13 通用卡片 ---------- */
.card {
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-card);
  padding: 24px;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}
.card:hover { border-color: var(--c-accent); box-shadow: var(--shadow-card); }

/* ---------- 19.14 联系信息卡片 ---------- */
.contact-list { display: grid; gap: 16px; }
.contact-item {
  display: flex;
  gap: 14px;
  padding: 16px 18px;
  background: var(--c-card);
  border: 1px solid var(--c-border);
  border-radius: var(--r-btn);
}
.contact-item .ci-ic {
  flex: none;
  width: 40px; height: 40px;
  display: flex; align-items: center; justify-content: center;
  background: rgba(255,107,26,.12);
  border-radius: var(--r-btn);
  font-size: 18px;
}
.contact-item .ci-text { font-size: 14px; color: var(--c-text-sub); }
.contact-item .ci-text strong { display: block; color: var(--c-text); font-size: 15px; margin-bottom: 2px; }

/* ---------- 19.15 返回顶部按钮 ---------- */
.back-to-top {
  position: fixed;
  right: 20px;
  bottom: 20px;
  width: 44px; height: 44px;
  display: flex; align-items: center; justify-content: center;
  background: var(--c-accent);
  color: #fff;
  border-radius: 50%;
  font-size: 18px;
  font-weight: 700;
  box-shadow: 0 6px 18px rgba(0,0,0,.3);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--dur) var(--ease);
  z-index: 90;
}
.back-to-top:hover { background: var(--c-accent-2); transform: translateY(-2px); color: #fff; }
.back-to-top.is-visible { opacity: 1; visibility: visible; transform: none; }

/* ---------- 19.16 工具类 ---------- */
.text-center { text-align: center; }
.text-accent { color: var(--c-accent-2); }
.mt-0 { margin-top: 0; } .mt-1 { margin-top: 8px; } .mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; } .mt-4 { margin-top: 32px; } .mt-5 { margin-top: 48px; }
.mb-0 { margin-bottom: 0; } .mb-2 { margin-bottom: 16px; } .mb-3 { margin-bottom: 24px; }
.flex { display: flex; } .flex-wrap { flex-wrap: wrap; }
.gap-2 { gap: 8px; } .gap-3 { gap: 12px; } .gap-4 { gap: 16px; }
.items-center { align-items: center; } .justify-between { justify-content: space-between; }

/* ============================================================
   20. 通用组件响应式
   ============================================================ */
@media (max-width: 1200px) {
  .layout-sidebar { grid-template-columns: 220px 1fr; gap: 28px; }
}

@media (max-width: 768px) {
  .page-header { padding: 110px 0 48px; }
  .page-body { padding: 40px 0 56px; }

  .layout-sidebar { grid-template-columns: 1fr; gap: 24px; }
  .sidebar { position: static; }

  .form-grid { grid-template-columns: 1fr; gap: 16px; }
  .form-card { padding: 20px; }

  .prose h2 { margin-top: 36px; }
  .prose h3 { margin-top: 28px; }

  .steps { grid-template-columns: 1fr; }

  .back-to-top { right: 14px; bottom: 14px; width: 40px; height: 40px; }

  .pagination a, .pagination span { min-width: 34px; height: 34px; font-size: 13px; }
}

@media (max-width: 420px) {
  .contact-item { flex-direction: column; gap: 10px; }
  .spec-grid { grid-template-columns: 1fr; }
}