/* ============================================================
   伏达科技 Voda Tech — 全局样式系统
   设计风格：工程厚重风
   主色：深蓝 #1a365d  |  辅色：橙 #e67e22  |  底色：银灰 #EAEEF2
   字体：思源宋体(标题) + 思源黑体(正文)
   ============================================================ */

/* --- CSS Variables / Design Tokens --- */
:root {
  /* Colors */
  --color-primary: #1a365d;
  --color-primary-light: #264b7a;
  --color-primary-dark: #0f2340;
  --color-accent: #e67e22;
  --color-accent-light: #f0a04b;
  --color-accent-dark: #c96a15;

  --color-bg: #F5F3EF;
  --color-bg-white: #ffffff;
  --color-bg-card: #FDFCFA;

  --color-text: #1a202c;
  --color-text-secondary: #2d3748;
  --color-text-muted: #8899aa;
  --color-text-white: #ffffff;

  --color-border: #dde4ea;
  --color-border-light: #eef2f6;

  /* Typography */
  --font-heading: 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC', 'STSong', 'SimSun', 'KaiTi', serif;
  --font-body: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Microsoft YaHei', 'Heiti SC', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Menlo', monospace;

  /* Spacing scale */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

  /* Layout */
  --max-width: 1280px;
  --nav-height: 64px;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.10);

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
}

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
}

/* --- Typography --- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: 600;
  line-height: 1.3;
  color: var(--color-primary);
}

h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); }
h3 { font-size: clamp(1.25rem, 2.5vw, 1.5rem); }
h4 { font-size: 1.125rem; }

p { margin-bottom: var(--space-md); }

.hero-text-link {
  display: inline-block;
  margin-left: var(--space-lg);
  color: var(--color-text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color var(--transition-fast);
}
.hero-text-link:hover { color: var(--color-accent); }

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

/* --- Reference Note --- */

/* --- Skip-to-content link (accessibility) --- */
.skip-link {
  position: absolute;
  top: -100px;
  left: 16px;
  background: var(--color-accent);
  color: #fff;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  z-index: 10000;
  text-decoration: none;
  transition: top var(--transition-fast);
}
.skip-link:focus {
  top: 16px;
}
/* --- Focus visible indicator (keyboard accessibility) --- */
a:focus-visible,
.btn:focus-visible,
.nav-links a:focus-visible,
.card:focus-visible,
.notes-tag:focus-visible,
.nav-toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 2px;
}


/* --- Hero product screenshot --- */
.hero-screenshot {
  display: none;
}
@media (min-width: 900px) {
  .hero .container {
    display: flex;
    align-items: center;
    gap: var(--space-2xl);
  }
  .hero-content {
    text-align: left;
    flex: 1;
  }
  .hero-content h1 { font-size: clamp(1.8rem, 4vw, 2.8rem); }
  .hero-tags { justify-content: flex-start; }
  .hero-screenshot {
    display: block;
    flex: 1;
    max-width: 520px;
  }
  .hero-screenshot img {
    width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
  }
}

.ref-note {
  margin-top: var(--space-lg);
  padding: var(--space-sm) var(--space-md);
  background: var(--color-bg-card);
  border-left: 3px solid var(--color-primary);
  font-size: 0.85rem;
  color: var(--color-text-muted);
  line-height: 1.6;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

/* --- Utility Classes --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl);
}

.section {
  padding: var(--space-4xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--space-sm);
}
.section-subtitle {
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 1.05rem;
  margin-bottom: var(--space-3xl);
  font-weight: 300;
}

.bg-white { background-color: var(--color-bg-white); }
.bg-primary {
  background: linear-gradient(180deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
  color: var(--color-text-white);
  position: relative;
}
.bg-primary::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.03) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
}
.bg-accent { background-color: var(--color-accent); color: var(--color-text-white); }

.text-center { text-align: center; }
.text-muted { color: var(--color-text-secondary); }

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  display: flex;
  align-items: center;
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
}
.nav-logo:hover { color: var(--color-primary); }

.nav-logo-img {
  height: 36px;
  width: auto;
  vertical-align: middle;
}

.nav-logo svg {
  height: 36px;
  width: auto;
}

.nav-vodasafer {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--color-accent, #E67E22);
  letter-spacing: 0.5px;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: var(--space-xl);
  align-items: center;
}




.nav-links a {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  font-weight: 500;
  transition: color var(--transition-fast);
  position: relative;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width var(--transition-fast);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
}
.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  flex-direction: column;
  gap: 5px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-primary);
  transition: var(--transition-normal);
}

/* 展开时变为 ✕ 关闭按钮 */
.nav-toggle.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle.open span:nth-child(2) {
  opacity: 0;
}
.nav-toggle.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* --- Hero Section --- */
.hero {
  min-height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  padding-top: var(--nav-height);
  background:
    radial-gradient(ellipse 80% 60% at 50% 30%, #F5F3EF 0%, #E8E4DD 40%, #DFE3E8 100%);
}

/* 几何网格背景 */
.hero-geo-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  background-image:
    linear-gradient(rgba(26,54,93,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(26,54,93,0.04) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 50% 50% at 50% 50%, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 50% 50% at 50% 50%, black 30%, transparent 70%);
}

/* 阻尼振荡曲线 — 品牌视觉核心 */
.hero-curve {
  position: absolute;
  bottom: 2%;
  left: 0;
  width: 100%;
  height: 400px;
  z-index: 0;
  pointer-events: none;
  opacity: 0.4;
}

/* ── 阻尼振荡动画 ── */

/* 安全红线：淡入 */
.curve-redline {
  animation: fadeInLine 4s ease-in-out infinite;
}

/* 主曲线：从左到右绘制 */
.curve-main {
  stroke-dasharray: 2000;
  stroke-dashoffset: 2000;
  animation: drawCurve 4s 0.4s ease-in-out infinite;
}

/* 标签：延迟淡入 */
.curve-label {
  opacity: 0;
}
.curve-label-left  { animation: fadeInLabel 0.6s 1.2s ease-out both; }
.curve-label-mid   { animation: fadeInLabel 0.6s 1.6s ease-out both; }
.curve-label-right { animation: fadeInLabel 0.6s 2.0s ease-out both; }

/* 振荡点：弹出 */
.curve-dot {
  opacity: 0;
  transform-origin: center;
}
.dot-1 { animation: popDot 4s 0.6s ease-in-out infinite; }
.dot-2 { animation: popDot 4s 1.2s ease-in-out infinite; }
.dot-3 { animation: popDot 4s 1.8s ease-in-out infinite; }
.dot-4 { animation: popDot 4s 2.6s ease-in-out infinite; }

/* Keyframes */
@keyframes fadeInLine {
  0%, 100% { opacity: 0.2; }
  50%      { opacity: 0.7; }
}

@keyframes drawCurve {
  0%   { stroke-dashoffset: 2000; }
  50%  { stroke-dashoffset: 0; }
  100% { stroke-dashoffset: 2000; }
}

@keyframes fadeInLabel {
  0%, 100% { opacity: 0; }
  30%, 80% { opacity: 1; }
}

@keyframes popDot {
  0%, 100% { opacity: 0; transform: scale(0); }
  15%, 85% { opacity: 1; transform: scale(1); }
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 720px;
  text-align: center;
}

.hero-label {
  display: inline-block;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--color-accent);
  background: rgba(230,126,34,0.08);
  border: 1px solid rgba(230,126,34,0.2);
  padding: 4px 16px;
  border-radius: 20px;
  margin-bottom: var(--space-lg);
}

.hero-content h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  margin-bottom: var(--space-lg);
  color: var(--color-primary);
  line-height: 1.3;
}

.hero-content .subtitle {
  font-size: clamp(1rem, 2vw, 1.15rem);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xl);
  font-weight: 300;
  line-height: 1.8;
}

.hero-tags {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: var(--space-2xl);
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.85rem;
  color: var(--color-primary);
  background: rgba(26,54,93,0.06);
  padding: var(--space-xs) var(--space-md);
  border-radius: 20px;
  border: 1px solid rgba(26,54,93,0.12);
}

.hero-btn-outline {
  color: var(--color-primary) !important;
  border-color: rgba(26,54,93,0.25) !important;
  margin-left: 12px;
}

.hero-btn-outline:hover {
  color: var(--color-primary) !important;
  border-color: var(--color-primary) !important;
  background: rgba(26,54,93,0.04) !important;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 0.7rem 1.8rem;
  font-size: 1rem;
  font-weight: 600;
  font-family: var(--font-body);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn-primary {
  background: var(--color-accent);
  color: white;
}
.btn-primary:hover {
  background: var(--color-accent-dark);
  color: white;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}
.btn-outline:hover {
  background: var(--color-primary);
  color: white;
  transform: translateY(-1px);
}

.btn-lg {
  padding: 0.85rem 2.2rem;
  font-size: 1.05rem;
}

/* --- Cards --- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: var(--space-xl);
}

.card {
  background: var(--color-bg-white);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  transition: all var(--transition-normal);
}

.card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  font-size: 1.5rem;
}

.card-icon.blue { background: rgba(26,54,93,0.1); color: var(--color-primary); }
.card-icon.orange { background: rgba(230,126,34,0.1); color: var(--color-accent); }

.card h3 {
  font-size: 1.15rem;
  margin-bottom: var(--space-sm);
}

.card p {
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  margin-bottom: 0;
}

/* --- Trust Badges --- */
.trust-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-xl);
}

.trust-item {
  text-align: center;
  padding: var(--space-lg) var(--space-md);
}

.trust-number {
  font-family: var(--font-heading);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: var(--space-sm);
}

.trust-label {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  font-weight: 500;
}

/* --- Theory Cards (three-column) --- */
.theory-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-xl);
}

.theory-card {
  text-align: center;
  padding: var(--space-2xl) var(--space-xl);
  background: var(--color-bg-white);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border-light);
  position: relative;
  overflow: hidden;
}

/* Wave phase indicator at top of each theory card */
.theory-card::before {
  content: '';
  display: block;
  height: 4px;
  position: absolute;
  top: 0;
  left: 20%;
  right: 20%;
  border-radius: 0 0 4px 4px;
}

.theory-card.wave-phase::before { background: var(--color-accent); height: 12px; border-radius: 0 0 50% 50%; }
.theory-card.adjust-phase::before { background: var(--color-accent); height: 6px; border-radius: 0 0 50% 50%; opacity: 0.6; }
.theory-card.stable-phase::before { background: var(--color-primary); height: 3px; border-radius: 0; opacity: 0.5; }

.theory-card h3 {
  margin-bottom: var(--space-sm);
}

.theory-card .theory-formula {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  color: var(--color-accent);
  font-weight: 700;
  margin-bottom: var(--space-md);
  text-align: center;
}

/* (theory-card link style) */
.theory-card a {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  color: var(--color-accent);
  font-weight: 700;
  margin-bottom: var(--space-md);
}

.theory-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
}

/* --- Contact Section --- */
.contact-section {
  text-align: center;
  padding: var(--space-4xl) 0;
}

.contact-email {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}

.contact-email:hover {
  color: var(--color-accent);
}

.contact-wechat {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-primary);
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}

/* --- Footer --- */
.footer {
  background: var(--color-primary-dark);
  color: rgba(255,255,255,0.7);
  padding: var(--space-2xl) 0;
  font-size: 0.9rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--space-md);
}

.footer-links {
  display: flex;
  gap: var(--space-lg);
}




.footer-links a {
  color: rgba(255,255,255,0.6);
  font-size: 0.85rem;
}
.footer-links a:hover {
  color: var(--color-accent-light);
}

/* Damped oscillation line in footer */
.footer-wave {
  margin-top: var(--space-lg);
  padding-top: var(--space-lg);
  border-top: 1px solid rgba(255,255,255,0.08);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xl);
  font-size: 0.8rem;
  color: rgba(255,255,255,0.35);
}

.footer-wave .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: rgba(255,255,255,0.3);
}

/* --- Page Header (sub-pages) --- */
.page-header {
  padding-top: calc(var(--nav-height) + var(--space-3xl));
  padding-bottom: var(--space-2xl);
  background:
    linear-gradient(180deg, #1a365d 0%, #264b7a 40%, #F5F3EF 100%);
  text-align: center;
  position: relative;
  overflow: hidden;
}

/* 子页面顶部的网格纹理 */
.page-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
  background-size: 50px 50px;
  pointer-events: none;
}

.page-header h1 {
  margin-bottom: var(--space-sm);
  color: #ffffff;
  position: relative;
}

.page-header p {
  color: rgba(255,255,255,0.7);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
  position: relative;
}

/* --- Feature List --- */
.feature-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-lg);
}

.feature-item {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-lg);
  background: var(--color-bg-white);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border-light);
}

.feature-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
  width: 40px;
  text-align: center;
}

.feature-text h4 {
  font-size: 1rem;
  margin-bottom: var(--space-xs);
}

.feature-text p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin: 0;
}

/* --- Scenario Cards --- */
.scenario-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
  padding: var(--space-3xl) 0;
  border-bottom: 1px solid var(--color-border-light);
}

.scenario-card:last-child { border-bottom: none; }

.scenario-card.reverse {
  direction: rtl;
}
.scenario-card.reverse .scenario-content {
  direction: ltr;
}

.scenario-icon {
  font-size: 4rem;
  text-align: center;
  padding: var(--space-3xl);
  background: var(--color-bg-card);
  border-radius: var(--radius-lg);
}

.scenario-content h3 {
  margin-bottom: var(--space-md);
}

.scenario-list {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.scenario-list li {
  background: rgba(26,54,93,0.06);
  color: var(--color-primary);
  padding: var(--space-xs) var(--space-md);
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
}

/* --- Timeline --- */
.timeline {
  position: relative;
  max-width: 600px;
  margin: 0 auto;
  padding-left: var(--space-2xl);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-border);
}

.timeline-item {
  position: relative;
  margin-bottom: var(--space-xl);
  padding-left: var(--space-xl);
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -26px;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid white;
  box-shadow: var(--shadow-sm);
}

.timeline-year {
  font-weight: 700;
  color: var(--color-accent);
  font-size: 0.95rem;
  margin-bottom: var(--space-xs);
}

.timeline-text {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
}

/* --- Knowledge / Notes Page --- */
.notes-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-2xl);
}

.notes-column {
  background: var(--color-bg-white);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  border: 1px solid var(--color-border-light);
}

.notes-column h3 {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-md);
  border-bottom: 2px solid var(--color-border-light);
}

.notes-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.notes-tag {
  background: var(--color-bg-card);
  color: var(--color-text-secondary);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: 1px solid transparent;
  display: block;
  user-select: none;
}

.notes-tag:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(230,126,34,0.05);
}

.notes-tag.active {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(230,126,34,0.1);
  font-weight: 600;
}

/* Expandable detail */
.notes-group {
  width: 100%;
}

.notes-group.filtered-out {
  display: none;
}

.notes-detail {
  display: none;
  background: #fafbfc;
  border-radius: var(--radius-sm);
  padding: var(--space-md);
  margin: var(--space-xs) 0 var(--space-sm);
  border-left: 3px solid var(--color-accent);
}

.notes-detail.open {
  display: block;
}

.notes-detail ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.notes-detail li {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  padding: 4px 0;
  border-bottom: 1px solid var(--color-border-light);
  line-height: 1.6;
}

.notes-detail li:last-child {
  border-bottom: none;
}

/* Article content inside notes-detail */
.article-content h4 {
  font-family: var(--font-heading);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-primary);
  margin: 14px 0 6px;
}

.article-content ol, .article-content ul {
  margin: 8px 0;
  padding-left: 18px;
}

.article-content li {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  padding: 3px 0;
  line-height: 1.8;
}

.article-content p {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  line-height: 1.9;
  margin-bottom: 8px;
}

.article-content strong {
  color: var(--color-primary);
}

.col-desc {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-bottom: var(--space-lg);
}

.notes-search {
  width: 100%;
  padding: var(--space-md);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-family: var(--font-body);
  margin-bottom: var(--space-xl);
  transition: border-color var(--transition-fast);
}

.notes-search:focus {
  outline: none;
  border-color: var(--color-accent);
}

/* --- Download Page --- */
.download-section {
  margin-bottom: var(--space-3xl);
}

.download-section h3 {
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-sm);
  border-bottom: 2px solid var(--color-border-light);
}

.download-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--color-border-light);
}

.download-item:last-child { border-bottom: none; }

.download-info {
  flex: 1;
}

.download-name {
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 2px;
}

.download-meta {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}


.download-meta a {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.download-link {
  flex-shrink: 0;
  margin-left: var(--space-lg);
}

/* --- Legal Pages (Privacy / Terms) --- */
.legal-content {
  max-width: 720px;
  margin: 0 auto;
}

.legal-content h2 {
  margin-top: var(--space-2xl);
  margin-bottom: var(--space-md);
}

.legal-content p,
.legal-content ul {
  color: var(--color-text-secondary);
  line-height: 1.8;
}

.legal-content ul {
  padding-left: var(--space-xl);
  margin-bottom: var(--space-md);
}

/* --- About Page --- */
.about-story {
  max-width: 720px;
  margin: 0 auto;
  font-size: 1.05rem;
  line-height: 1.9;
}

.about-story p {
  margin-bottom: var(--space-lg);
}

/* --- Mobile Responsive --- */
@media (max-width: 768px) {
  :root {
    --nav-height: 0;
    --bottom-nav-height: 56px;
  }

  .container {
    padding: 0 var(--space-lg);
  }

  .section {
    padding: var(--space-3xl) 0;
  }

  /* 页面底部留出导航栏高度 */
  body {
    padding-bottom: var(--bottom-nav-height);
  }

  /* ── 顶部导航 → 底部固定 ── */
  .nav {
    position: fixed;
    top: auto;
    bottom: 0;
    left: 0;
    right: 0;
    height: var(--bottom-nav-height);
    background: rgba(255,255,255,0.97);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-top: 1px solid var(--color-border);
    border-bottom: none;
    box-shadow: 0 -2px 12px rgba(0,0,0,0.05);
    display: flex;
    z-index: 1000;
  }

  .nav .container {
    padding: 0 4px;
    width: 100%;
  }

  /* 隐藏"伏达科技"文字logo */
  .nav-logo {
    display: none;
  }

  /* 链接水平等分排列 */
  .nav-links {
    position: static;
    display: flex;
    flex-direction: row;
    justify-content: space-around;
    align-items: center;
    width: 100%;
    height: 100%;
    padding: 0;
    gap: 0;
    background: transparent;
    transform: none;
    transition: none;
  }

  


.nav-links a {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2px;
    font-size: 10px;
    font-weight: 500;
    color: var(--color-text-muted);
    padding: 4px 2px;
    border-radius: 8px;
    min-width: 0;
    text-align: center;
    position: relative;
  }

  /* 图标 */
  .nav-links a::before {
    display: block;
    font-size: 20px;
    line-height: 1;
    margin-bottom: 1px;
  }

  .nav-links a[href="index.html"]::before { content: "🏠"; }
  .nav-links a[href="products.html"]::before { content: "📦"; }
  .nav-links a[href="solutions.html"]::before { content: "🔧"; }
  .nav-links a[href="notes.html"]::before { content: "📖"; }
  .nav-links a[href="downloads.html"]::before { content: "⬇️"; }
  .nav-links a[href="about.html"]::before { content: "ℹ️"; }

  /* 去掉下划线动画 */
  .nav-links a::after {
    display: none;
  }

  /* 活跃态 */
  .nav-links a.active {
    color: var(--color-accent);
    font-weight: 600;
  }

  .nav-links a:active {
    background: rgba(230,126,34,0.08);
  }

  /* 隐藏汉堡菜单 */
  .nav-toggle {
    display: none;
  }

  /* ── Hero 移动端适配 ── */
  .hero {
    min-height: 70vh;
    padding-top: 0;
  }

  .hero-content h1 {
    font-size: 1.6rem;
  }

  .hero-tags {
    gap: var(--space-sm);
  }

  .hero-tag {
    font-size: 0.75rem;
    padding: var(--space-xs) var(--space-sm);
  }

  /* Grids collapse */
  .card-grid { grid-template-columns: 1fr; }
  .trust-grid { grid-template-columns: repeat(2, 1fr); }
  .theory-grid { grid-template-columns: 1fr; }
  .feature-list { grid-template-columns: 1fr; }
  .notes-layout { grid-template-columns: 1fr; }

  .scenario-card {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  .scenario-card.reverse { direction: ltr; }

  /* 页脚在底部导航上方留空 */
  .footer {
    padding-bottom: calc(var(--space-2xl) + var(--bottom-nav-height));
  }

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  .footer-wave {
    flex-wrap: wrap;
    gap: var(--space-md);
  }

  /* 子页面 header 不用顶部留白了 */
  .page-header {
    padding-top: var(--space-2xl);
  }

  /* 下载页按钮移动端放大到44px以上触控区 */
  .download-item .btn-outline {
    min-height: 44px;
    min-width: 44px;
    padding: 8px 16px;
    font-size: 0.9rem;
  }

  /* Hero CTA 按钮堆叠 */
  .hero-content .btn {
    display: block;
    width: 100%;
    text-align: center;
    margin: 0 0 8px;
  }

  .hero-content .btn + .btn {
    margin-left: 0;
  }
}

@media (max-width: 480px) {
  .trust-grid { grid-template-columns: 1fr; }
  .hero-tags { flex-direction: column; align-items: flex-start; }
}

/* --- Wide Screen (Full-screen / 半屏窗口化用户) --- */
@media (min-width: 1600px) {
  /* 内容区适度放宽，但不拉伸正文行宽 */
  :root {
    --max-width: 1400px;
  }

  /* Hero 首屏在大屏上保持居中，视觉重心不散 */
  .hero-content {
    max-width: 780px;
  }

  /* 产品卡片在大屏上三列更舒展 */
  .card-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-2xl);
  }

  /* 解决方案双栏间距加大 */
  .scenario-card {
    gap: var(--space-4xl);
  }

  /* 伏达笔记双栏 */
  .notes-layout {
    gap: var(--space-3xl);
  }
}

/* --- 超宽屏 (>2200px) 全屏用户 --- */
@media (min-width: 2200px) {
  /* 2K/4K 全屏时，container 收窄到舒服的阅读宽度，
     背景色自然填充两侧，不突兀 */
  :root {
    --max-width: 1400px;
  }

  /* 产品卡片在超大屏上四列 */
  .card-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .scenario-card {
    grid-template-columns: 1fr 1.2fr;
    gap: var(--space-4xl);
  }
}

/* ============================================================
   Section: 服务领域 cards
   ============================================================ */

/* --- AI Card highlight (visually emphasize core differentiator) --- */
.card.card-highlight {
  border-left: 3px solid var(--color-accent);
  background: linear-gradient(135deg, #FFF8F0 0%, var(--color-bg-white) 100%);
}

.scene-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-xl);
  margin-top: var(--space-xl);
}
@media (max-width: 768px) {
  
/* --- AI Card highlight (visually emphasize core differentiator) --- */
.card.card-highlight {
  border-left: 3px solid var(--color-accent);
  background: linear-gradient(135deg, #FFF8F0 0%, var(--color-bg-white) 100%);
}

.scene-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 480px) {
  
/* --- AI Card highlight (visually emphasize core differentiator) --- */
.card.card-highlight {
  border-left: 3px solid var(--color-accent);
  background: linear-gradient(135deg, #FFF8F0 0%, var(--color-bg-white) 100%);
}

.scene-grid { grid-template-columns: 1fr; }
}
.scene-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: var(--space-xl) var(--space-lg);
  text-align: center;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}
.scene-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.scene-icon {
  font-size: 2.2rem;
  margin-bottom: var(--space-sm);
}
.scene-card h3 {
  font-size: 1.05rem;
  margin-bottom: var(--space-sm);
  color: var(--color-primary);
}
.scene-card p {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}


/* --- Reduced motion preference (accessibility) --- */
@media (prefers-reduced-motion: reduce) {
  .curve-redline,
  .curve-main,
  .curve-dot,
  .curve-label,
  .curve-label-left,
  .curve-label-mid,
  .curve-label-right {
    animation: none;
  }
  .curve-redline { opacity: 0.5; }
  .curve-main { stroke-dashoffset: 0; }
  .curve-label,
  .curve-label-left,
  .curve-label-mid,
  .curve-label-right { opacity: 1; }
  .curve-dot,
  .dot-1, .dot-2, .dot-3, .dot-4 { opacity: 1; transform: scale(1); }
  html { scroll-behavior: auto; }
}


/* --- Footer navigation --- */
.footer-brand { max-width: 220px; }
.footer-nav {
  display: flex;
  gap: var(--space-2xl);
}
.footer-nav-col {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}
.footer-nav-title {
  color: rgba(255,255,255,0.5);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-xs);
}
.footer-nav-col a {
  color: rgba(255,255,255,0.6);
  font-size: 0.85rem;
  text-decoration: none;
  transition: color var(--transition-fast);
}
.footer-nav-col a:hover { color: var(--color-accent-light); }
@media (max-width: 768px) {
  .footer-content { flex-direction: column; align-items: flex-start; gap: var(--space-xl); }
  .footer-nav { gap: var(--space-xl); }
}


/* --- Inline SVG Icons (replacing emoji) --- */
.icon-inline {
  flex-shrink: 0;
  vertical-align: middle;
}
.btn .icon-inline { width: 18px; height: 18px; }
.card-icon .icon-inline { width: 28px; height: 28px; }
.contact-email .icon-inline,
.contact-wechat .icon-inline { width: 22px; height: 22px; }


/* ================================================================
   Print Styles
   ================================================================ */
@media print {
  /* Hide non-content elements */
  .nav, .nav-toggle, .skip-link,
  .hero-curve, .hero-geo-bg,
  .footer-wave, .footer-links,
  .hero-screenshot, .footer-brand, .footer-nav,
  .btn { display: none !important; }

  /* Remove backgrounds and shadows */
  *, *::before, *::after {
    background: transparent !important;
    box-shadow: none !important;
  }

  body {
    color: #000 !important;
    background: #fff !important;
    font-size: 12pt;
    line-height: 1.5;
  }

  h1, h2, h3 { color: #000 !important; page-break-after: avoid; }
  .section { padding: 1rem 0; }
  .hero { min-height: auto; padding: 1rem 0; }
  .hero-content h1 { font-size: 18pt; }
  .hero-label { color: #444 !important; }

  .page-header {
    background: none !important;
    padding: 1rem 0;
  }
  .page-header h1 { color: #000 !important; }
  .page-header p { color: #444 !important; }

  .card, .scene-card, .theory-card, .trust-item, .feature-item {
    border: 1px solid #ccc !important;
    break-inside: avoid;
  }

  /* Show link URLs */
  a[href]::after {
    content: " (" attr(href) ")";
    font-size: 9pt;
    color: #666;
  }
  .nav a[href]::after { content: none; }
  .btn[href]::after { content: none; }

  .footer {
    padding: 0.5rem 0;
    border-top: 1px solid #ccc;
    text-align: center;
  }
  .footer-content { flex-direction: column; align-items: center; }

  .trust-number { color: #000 !important; }
  .trust-label { color: #444 !important; }
}


/* ================================================================
   Dark Mode (prefers-color-scheme: dark)
   ================================================================ */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg: #1a1c1e;
    --color-bg-white: #252729;
    --color-bg-card: #2a2c2e;
    --color-text: #e4e4e7;
    --color-text-secondary: #c5c5cc;
    --color-text-muted: #8a8a94;
    --color-text-white: #e4e4e7;
    --color-border: #35373a;
    --color-border-light: #2e3033;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
  }

  body { background: var(--color-bg); }

  /* Hero section keeps dark blue — already dark, just soften */
  .hero { background: #121820; }
  .hero-label { color: var(--color-accent-light); }
  .hero-content h1 { color: #fff; }
  .subtitle { color: rgba(255,255,255,0.7); }

  /* Cards */
  .card, .scene-card, .theory-card, .feature-item {
    background: var(--color-bg-card);
    border-color: var(--color-border);
  }
  .card-icon.blue { background: rgba(38,75,122,0.25); }
  .card-icon.orange { background: rgba(230,126,34,0.15); }

  /* Trust section — already dark blue, works well */
  #trust .section-title { color: #fff; }

  /* Section bg-white override */
  .bg-white { background: var(--color-bg); }

  /* Page header */
  .page-header {
    background: linear-gradient(180deg, #1a365d 0%, #1a1c1e 100%);
  }

  /* Navigation */
  .nav {
    background: rgba(26,28,30,0.97);
    border-bottom-color: var(--color-border);
  }
  .nav-logo { color: var(--color-text); }

  /* Buttons */
  .btn-outline {
    color: var(--color-accent-light);
    border-color: var(--color-accent);
  }
  .btn-outline:hover { color: #fff; }

  /* Contact section */
  .contact-email, .contact-wechat { color: var(--color-text); }

  /* Download items */
  .download-section h3 { color: var(--color-text); }

  /* Notes page */
  .notes-column { background: var(--color-bg-card); border-color: var(--color-border); }
  .notes-detail { background: var(--color-bg); }
  .notes-search {
    background: var(--color-bg-card);
    color: var(--color-text);
    border-color: var(--color-border);
  }

  /* Legal pages */
  .legal-content h2 { color: var(--color-text); }

  /* Card highlight keeps warm accent */
  .card-highlight { background: linear-gradient(135deg, #2a2c2e 0%, #312a1f 100%); }

  .icon-inline {
    stroke: currentColor;
  }
}

/* Product screenshots */
@media (min-width: 768px) {

.scenario-screen {
  border-radius: 8px; box-shadow: 0 2px 12px rgba(0,0,0,.1);
  border: 1px solid var(--color-border);
  object-fit: cover;
  width: 100%; max-width: 280px; height: auto;
}
@media (min-width: 768px) {
  .scenario-screen { max-width: 340px; }
}