/* ===== CSS Variables ===== */
:root {
  /* Brand Colors - XPENG inspired */
  --color-primary: #0066FF;
  --color-primary-hover: #0052CC;
  --color-primary-light: #E6F0FF;
  --color-primary-bg: #CCE0FF;
  --color-accent: #00D4AA;
  --color-accent-light: #E6FFF8;

  /* Text Colors */
  --color-text: #0F172A;
  --color-text-secondary: #475569;
  --color-text-muted: #94A3B8;

  /* Background Colors */
  --color-bg: #FFFFFF;
  --color-bg-alt: #F8FAFC;
  --color-bg-card: #FFFFFF;

  /* Border Colors */
  --color-border: #E2E8F0;
  --color-border-light: #F1F5F9;

  /* Semantic Colors */
  --color-success: #10B981;
  --color-warning: #F59E0B;
  --color-danger: #EF4444;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 40px -12px rgba(0, 0, 0, 0.15);

  /* Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  /* Layout */
  --max-width: 1320px;
  --content-padding: clamp(16px, 3vw, 32px);
  --header-height: 72px;

  /* Transitions */
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* ===== Container ===== */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--content-padding);
}

/* ===== Header / Navigation ===== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  z-index: 100;
  transition: all var(--transition-normal);
}

.header.scrolled {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.header-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.header-logo-img {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  box-shadow: 0 2px 8px rgba(0, 102, 255, 0.2);
}

.header-logo-text {
  font-size: 20px;
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-link {
  padding: 10px 20px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text-secondary);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.nav-link:hover {
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.06);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

/* Mobile menu button */
.header-menu-btn {
  display: none;
  flex-direction: column;
  gap: 6px;
  padding: 12px;
  border-radius: var(--radius-md);
  background: none;
  border: none;
  cursor: pointer;
}

.header-menu-btn:hover {
  background-color: var(--color-bg-alt);
}

.menu-line {
  width: 24px;
  height: 2.5px;
  background-color: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition-normal);
}

.header-menu-btn.active .menu-line:nth-child(1) {
  transform: translateY(8.5px) rotate(45deg);
}

.header-menu-btn.active .menu-line:nth-child(2) {
  opacity: 0;
  transform: scaleX(0);
}

.header-menu-btn.active .menu-line:nth-child(3) {
  transform: translateY(-8.5px) rotate(-45deg);
}

/* Mobile menu */
.mobile-menu {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(255, 255, 255, 0.98);
  backdrop-filter: blur(20px);
  z-index: 99;
  padding: 24px;
  transform: translateX(100%);
  transition: transform var(--transition-normal);
}

.mobile-menu.open {
  transform: translateX(0);
}

.mobile-nav {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.mobile-nav-link {
  display: block;
  padding: 18px 24px;
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
  border-radius: var(--radius-lg);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.mobile-nav-link:hover {
  background: rgba(0, 102, 255, 0.06);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  color: var(--color-primary);
}

/* ===== Hero / 平台简介 ===== */
.hero {
  padding: 88px 0 56px;
  text-align: center;
  background: linear-gradient(135deg, #F0F7FF 0%, #E6F0FF 50%, #F0FAFF 100%);
}

.hero-content {
  max-width: 680px;
  margin: 0 auto;
  padding: 0 24px;
}

.hero-slogan {
  font-size: clamp(24px, 3vw, 34px);
  color: var(--color-text);
  margin-bottom: 16px;
  font-weight: 800;
  line-height: 1.4;
  letter-spacing: -0.02em;
}

.hero-divider {
  width: 48px;
  height: 3px;
  background: var(--color-primary);
  border-radius: 2px;
  margin: 0 auto 24px;
}

.hero-desc {
  font-size: clamp(15px, 1.5vw, 17px);
  color: var(--color-text-secondary);
  line-height: 1.8;
  max-width: 560px;
  margin-left: auto;
  margin-right: auto;
  font-weight: 500;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 32px;
  font-size: 16px;
  font-weight: 700;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  text-decoration: none;
  border: none;
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary) 0%, #3388FF 100%);
  color: #FFFFFF;
  box-shadow: 0 4px 16px rgba(0, 102, 255, 0.3);
}

.btn-primary:hover {
  background: linear-gradient(135deg, var(--color-primary-hover) 0%, #2277EE 100%);
  box-shadow: 0 6px 24px rgba(0, 102, 255, 0.4);
  transform: translateY(-2px);
}

.btn-outline {
  background: rgba(255, 255, 255, 0.06);
  color: #FFFFFF;
  border: 1px solid rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  box-shadow: 
    inset 0 1px 0 rgba(255, 255, 255, 0.1),
    0 2px 8px rgba(0, 0, 0, 0.1);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.35);
  box-shadow: 
    inset 0 1px 0 rgba(255, 255, 255, 0.15),
    0 4px 16px rgba(0, 0, 0, 0.15);
}

/* ===== Stats Section ===== */
.stats {
  position: relative;
  padding: 0 0 64px;
  background: linear-gradient(135deg, #F0F7FF 0%, #E6F0FF 50%, #F0FAFF 100%);
  overflow: hidden;
}

/* Stats decorative orbs */
.stats::before {
  content: '';
  position: absolute;
  top: -100px;
  right: -100px;
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(0, 102, 255, 0.06) 0%, transparent 60%);
  border-radius: 50%;
  pointer-events: none;
}

.stats::after {
  content: '';
  position: absolute;
  bottom: -80px;
  left: -80px;
  width: 250px;
  height: 250px;
  background: radial-gradient(circle, rgba(0, 212, 170, 0.05) 0%, transparent 60%);
  border-radius: 50%;
  pointer-events: none;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  text-align: center;
}

.stat-item {
  padding: 24px 16px;
  background: rgba(255, 255, 255, 0.5);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-radius: var(--radius-lg);
  border: 1px solid rgba(255, 255, 255, 0.6);
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.03),
    inset 0 1px 0 rgba(255, 255, 255, 0.5);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.stat-item:hover {
  transform: translateY(-2px);
  box-shadow: 
    0 4px 16px rgba(0, 0, 0, 0.06),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

.stat-num {
  display: block;
  font-size: clamp(32px, 4vw, 44px);
  font-weight: 900;
  background: linear-gradient(135deg, var(--color-primary) 0%, #6366F1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.stat-label {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text-secondary);
}

/* ===== Section Titles ===== */
.section-title {
  font-size: clamp(28px, 3.5vw, 40px);
  font-weight: 900;
  color: var(--color-text);
  text-align: center;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.section-subtitle {
  font-size: 17px;
  color: var(--color-text-secondary);
  text-align: center;
  margin-bottom: 56px;
  line-height: 1.6;
}

/* ===== Features Section ===== */
.features {
  position: relative;
  padding: 100px 0;
  background-color: var(--color-bg);
  overflow: hidden;
}

/* Subtle dot pattern */
.features::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-image: radial-gradient(circle, rgba(0, 0, 0, 0.03) 1px, transparent 1px);
  background-size: 24px 24px;
  pointer-events: none;
}

.features-grid {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card-link {
  text-decoration: none;
  color: inherit;
  display: block;
}

.feature-card-link:hover .feature-card {
  border-color: rgba(0, 102, 255, 0.2);
  background: rgba(255, 255, 255, 0.85);
  box-shadow: 
    0 8px 32px rgba(0, 0, 0, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.8);
  transform: translateY(-4px);
}

.feature-card-link:hover .feature-card::before {
  opacity: 1;
}

.feature-card-link:hover .feature-icon {
  transform: scale(1.1) rotate(-5deg);
}

.feature-card {
  position: relative;
  padding: 32px 28px;
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: var(--radius-xl);
  transition: all var(--transition-normal);
  overflow: hidden;
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.04),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.feature-card:hover {
  border-color: rgba(0, 102, 255, 0.2);
  background: rgba(255, 255, 255, 0.85);
  box-shadow: 
    0 8px 32px rgba(0, 0, 0, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.8);
  transform: translateY(-4px);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  border-radius: var(--radius-lg);
  margin-bottom: 20px;
  transition: transform var(--transition-normal);
}

.feature-card:hover .feature-icon {
  transform: scale(1.1) rotate(-5deg);
}

.feature-name {
  font-size: 19px;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.feature-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

.feature-tag {
  position: absolute;
  top: 24px;
  right: 24px;
  display: inline-block;
  padding: 5px 14px;
  font-size: 12px;
  font-weight: 700;
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.08);
  backdrop-filter: blur(12px) saturate(180%);
  -webkit-backdrop-filter: blur(12px) saturate(180%);
  border: 1px solid rgba(0, 102, 255, 0.12);
  border-radius: 100px;
  letter-spacing: 0.02em;
  box-shadow: 0 1px 4px rgba(0, 102, 255, 0.1);
}

/* ===== Models Section ===== */
.models {
  position: relative;
  padding: 100px 0;
  background: linear-gradient(180deg, var(--color-bg-alt) 0%, #F0F7FF 100%);
}

.models-grid {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 16px;
  max-width: 720px;
  margin: 0 auto;
}

.model-chip {
  padding: 14px 32px;
  font-size: 18px;
  font-weight: 800;
  color: var(--color-text);
  background: rgba(255, 255, 255, 0.6);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: 100px;
  transition: all var(--transition-normal);
  cursor: default;
  letter-spacing: -0.01em;
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.04),
    inset 0 1px 0 rgba(255, 255, 255, 0.5);
}

.model-chip:hover {
  border-color: rgba(0, 102, 255, 0.3);
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.08);
  transform: translateY(-2px);
  box-shadow: 
    0 4px 16px rgba(0, 102, 255, 0.12),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
}

/* ===== Philosophy Section ===== */
.philosophy {
  position: relative;
  padding: 100px 0;
  background-color: var(--color-bg);
  overflow: hidden;
}

/* Decorative gradient */
.philosophy::after {
  content: '';
  position: absolute;
  bottom: -200px;
  right: -200px;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(0, 212, 170, 0.08) 0%, transparent 60%);
  border-radius: 50%;
  pointer-events: none;
}

.philosophy-grid {
  position: relative;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.philosophy-card {
  padding: 36px;
  background: rgba(255, 255, 255, 0.65);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid rgba(255, 255, 255, 0.7);
  border-radius: var(--radius-xl);
  transition: all var(--transition-normal);
  box-shadow: 
    0 2px 8px rgba(0, 0, 0, 0.04),
    inset 0 1px 0 rgba(255, 255, 255, 0.5);
}

.philosophy-card:hover {
  border-color: rgba(0, 102, 255, 0.2);
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 
    0 8px 24px rgba(0, 0, 0, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.7);
  transform: translateY(-2px);
}

.philosophy-num {
  display: inline-block;
  font-size: 14px;
  font-weight: 800;
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.08);
  backdrop-filter: blur(12px) saturate(180%);
  -webkit-backdrop-filter: blur(12px) saturate(180%);
  border: 1px solid rgba(0, 102, 255, 0.12);
  padding: 6px 14px;
  border-radius: 100px;
  margin-bottom: 16px;
  letter-spacing: 0.05em;
  box-shadow: 0 1px 4px rgba(0, 102, 255, 0.08);
}

.philosophy-title {
  font-size: 22px;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

.philosophy-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ===== Download Section ===== */
.download {
  position: relative;
  padding: 100px 0;
  background: linear-gradient(180deg, #F0F7FF 0%, var(--color-bg-alt) 100%);
  overflow: hidden;
}

.download::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--color-primary-bg), transparent);
}

/* Download decorative orb */
.download::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(0, 102, 255, 0.04) 0%, transparent 50%);
  border-radius: 50%;
  pointer-events: none;
}

.download-content {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 72px;
  max-width: 800px;
  margin: 0 auto;
}

.download-qrcode {
  text-align: center;
  flex-shrink: 0;
}

.qrcode-img {
  width: 260px;
  height: 260px;
  border-radius: var(--radius-xl);
  border: 1px solid rgba(255, 255, 255, 0.6);
  background: rgba(255, 255, 255, 0.5);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  box-shadow: 
    0 8px 32px rgba(0, 0, 0, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.6);
  transition: transform var(--transition-normal), box-shadow var(--transition-normal);
}

.qrcode-img:hover {
  transform: scale(1.02);
  box-shadow: 
    0 12px 40px rgba(0, 0, 0, 0.12),
    inset 0 1px 0 rgba(255, 255, 255, 0.7);
}

.qrcode-tip {
  margin-top: 16px;
  font-size: 15px;
  color: var(--color-text-secondary);
  font-weight: 600;
}

.download-info {
  flex: 1;
}

.download-heading {
  font-size: 24px;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

.download-steps {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 28px;
  list-style: none;
  counter-reset: step-counter;
}

.download-steps li {
  position: relative;
  padding-left: 32px;
  font-size: 16px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  counter-increment: step-counter;
}

.download-steps li::before {
  content: counter(step-counter);
  position: absolute;
  left: 0;
  top: 2px;
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 800;
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.08);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(0, 102, 255, 0.12);
  border-radius: 50%;
  box-shadow: 0 1px 4px rgba(0, 102, 255, 0.08);
}

.download-note {
  padding: 20px 24px;
  background: rgba(0, 102, 255, 0.06);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-radius: var(--radius-lg);
  border: 1px solid rgba(0, 102, 255, 0.12);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.5);
}

.download-note p {
  font-size: 15px;
  color: var(--color-primary);
  line-height: 1.8;
  font-weight: 600;
}

/* ===== Footer ===== */
.footer {
  padding: 64px 0 40px;
  background-color: var(--color-bg-alt);
  color: var(--color-text-secondary);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  gap: 48px;
  margin-bottom: 40px;
}

.footer-brand-name {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 20px;
  font-weight: 800;
  color: var(--color-text);
  margin-bottom: 12px;
}

.footer-brand-name img {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
}

.footer-brand-desc {
  font-size: 15px;
  color: var(--color-text-muted);
  line-height: 1.6;
}

.footer-links {
  display: flex;
  gap: 72px;
}

.footer-link-group h4 {
  font-size: 14px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 16px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.footer-link-group a {
  display: inline-block;
  font-size: 15px;
  color: var(--color-text-secondary);
  padding: 6px 12px;
  margin: -6px -12px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  text-decoration: none;
}

.footer-link-group a:hover {
  color: var(--color-primary);
  background: rgba(0, 102, 255, 0.06);
}

.footer-bottom {
  padding-top: 32px;
  border-top: 1px solid var(--color-border);
  text-align: center;
}

.footer-bottom p {
  font-size: 14px;
  color: var(--color-text-muted);
}

/* ===== Footer Disclaimer ===== */
.footer-disclaimer {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--color-border-light);
}

.footer-disclaimer p {
  font-size: 12px;
  color: var(--color-text-muted);
  line-height: 1.8;
  max-width: 900px;
  margin: 0 auto;
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 102, 255, 0.7);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  color: #FFFFFF;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.2);
  box-shadow: 
    0 4px 16px rgba(0, 102, 255, 0.25),
    inset 0 1px 0 rgba(255, 255, 255, 0.15);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  z-index: 50;
  border: none;
  cursor: pointer;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

.back-to-top:hover {
  transform: translateY(-4px);
  background: rgba(0, 102, 255, 0.85);
  box-shadow: 
    0 8px 24px rgba(0, 102, 255, 0.35),
    inset 0 1px 0 rgba(255, 255, 255, 0.2);
}

/* ===== Scroll Animation ===== */
.animate-on-scroll {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.8s cubic-bezier(0.4, 0, 0.2, 1), transform 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.animate-on-scroll.animated {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered animation delay for grid items */
.features-grid .feature-card:nth-child(1) { transition-delay: 0ms; }
.features-grid .feature-card:nth-child(2) { transition-delay: 50ms; }
.features-grid .feature-card:nth-child(3) { transition-delay: 100ms; }
.features-grid .feature-card:nth-child(4) { transition-delay: 150ms; }
.features-grid .feature-card:nth-child(5) { transition-delay: 200ms; }
.features-grid .feature-card:nth-child(6) { transition-delay: 250ms; }
.features-grid .feature-card:nth-child(7) { transition-delay: 300ms; }
.features-grid .feature-card:nth-child(8) { transition-delay: 350ms; }
.features-grid .feature-card:nth-child(9) { transition-delay: 400ms; }
.features-grid .feature-card:nth-child(10) { transition-delay: 450ms; }

/* ===== Gradient Text Helper ===== */
.gradient-text {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ===== Promo Banner - 鹏友车机音效引流 ===== */
.promo-banner {
  padding: 96px 0 0;
  position: relative;
  z-index: 3;
  margin-top: 0;
}

.promo-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 48px;
  padding: 40px 48px;
  background: linear-gradient(135deg, #0F172A 0%, #1E293B 40%, #1A1A2E 100%);
  border-radius: 20px;
  border: 1px solid rgba(99, 102, 241, 0.2);
  box-shadow:
    0 8px 40px rgba(0, 0, 0, 0.3),
    0 0 60px rgba(99, 102, 241, 0.08),
    inset 0 1px 0 rgba(255, 255, 255, 0.05);
  overflow: hidden;
  position: relative;
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

.promo-card:hover {
  border-color: rgba(99, 102, 241, 0.4);
  box-shadow:
    0 12px 48px rgba(0, 0, 0, 0.35),
    0 0 80px rgba(99, 102, 241, 0.15),
    inset 0 1px 0 rgba(255, 255, 255, 0.08);
  transform: translateY(-2px);
}

/* Glow orb decoration */
.promo-card::before {
  content: '';
  position: absolute;
  top: -120px;
  right: -60px;
  width: 360px;
  height: 360px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.12) 0%, rgba(139, 92, 246, 0.06) 30%, transparent 60%);
  border-radius: 50%;
  pointer-events: none;
}

.promo-card::after {
  content: '';
  position: absolute;
  bottom: -80px;
  left: -40px;
  width: 280px;
  height: 280px;
  background: radial-gradient(circle, rgba(0, 212, 170, 0.08) 0%, transparent 50%);
  border-radius: 50%;
  pointer-events: none;
}

.promo-content {
  position: relative;
  z-index: 1;
  flex: 1;
}

.promo-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  font-size: 13px;
  font-weight: 700;
  color: #C7D2FE;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: 100px;
  margin-bottom: 20px;
  letter-spacing: 0.02em;
}

.promo-title {
  font-size: clamp(24px, 3vw, 32px);
  font-weight: 900;
  color: #FFFFFF;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.promo-highlight {
  display: inline-block;
  background: linear-gradient(135deg, #818CF8 0%, #A78BFA 50%, #00D4AA 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.promo-desc {
  font-size: 16px;
  color: rgba(255, 255, 255, 0.7);
  line-height: 1.6;
  margin-bottom: 24px;
  max-width: 480px;
}

.promo-features {
  display: flex;
  gap: 20px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.promo-feature-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.6);
  font-weight: 600;
}

.promo-feature-icon {
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 212, 170, 0.15);
  border-radius: 50%;
  font-size: 11px;
  color: #00D4AA;
  flex-shrink: 0;
}

.btn-promo {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  font-size: 16px;
  font-weight: 700;
  color: #FFFFFF;
  background: linear-gradient(135deg, #6366F1 0%, #8B5CF6 100%);
  border-radius: 12px;
  text-decoration: none;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.35);
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.btn-promo:hover {
  background: linear-gradient(135deg, #4F46E5 0%, #7C3AED 100%);
  box-shadow: 0 6px 28px rgba(99, 102, 241, 0.5);
  transform: translateY(-2px);
}

.btn-promo:active {
  transform: scale(0.97);
}

/* Sound wave visual on the right */
.promo-visual {
  position: relative;
  z-index: 1;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.promo-wave-container {
  display: flex;
  align-items: flex-end;
  gap: 6px;
  height: 80px;
}

.promo-wave-bar {
  width: 6px;
  border-radius: 3px;
  background: linear-gradient(180deg, #818CF8 0%, #6366F1 100%);
  animation: waveAnim 1.2s ease-in-out infinite;
}

.promo-wave-bar:nth-child(1) { height: 24px; animation-delay: 0s; }
.promo-wave-bar:nth-child(2) { height: 48px; animation-delay: 0.1s; }
.promo-wave-bar:nth-child(3) { height: 36px; animation-delay: 0.2s; }
.promo-wave-bar:nth-child(4) { height: 64px; animation-delay: 0.3s; }
.promo-wave-bar:nth-child(5) { height: 44px; animation-delay: 0.4s; }
.promo-wave-bar:nth-child(6) { height: 56px; animation-delay: 0.5s; }
.promo-wave-bar:nth-child(7) { height: 28px; animation-delay: 0.6s; }
.promo-wave-bar:nth-child(8) { height: 50px; animation-delay: 0.7s; }
.promo-wave-bar:nth-child(9) { height: 40px; animation-delay: 0.8s; }
.promo-wave-bar:nth-child(10) { height: 32px; animation-delay: 0.9s; }

@keyframes waveAnim {
  0%, 100% { transform: scaleY(1); opacity: 0.7; }
  50% { transform: scaleY(1.8); opacity: 1; }
}

.promo-sound-icon {
  position: absolute;
  font-size: 80px;
  opacity: 0.06;
  pointer-events: none;
}

/* Navbar promo link */
.nav-link-promo {
  padding: 8px 18px !important;
  font-size: 14px !important;
  font-weight: 700 !important;
  color: #FFFFFF !important;
  background: linear-gradient(135deg, #6366F1 0%, #8B5CF6 100%) !important;
  border-radius: 100px !important;
  box-shadow: 0 2px 12px rgba(99, 102, 241, 0.3);
  margin-left: 8px;
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1) !important;
  letter-spacing: 0.01em;
}

.nav-link-promo:hover {
  background: linear-gradient(135deg, #4F46E5 0%, #7C3AED 100%) !important;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.45) !important;
  transform: translateY(-1px);
  color: #FFFFFF !important;
}

/* Mobile nav promo link */
.mobile-nav-link-promo {
  background: linear-gradient(135deg, #6366F1 0%, #8B5CF6 100%) !important;
  color: #FFFFFF !important;
  border-radius: 14px !important;
  font-weight: 700 !important;
  box-shadow: 0 2px 12px rgba(99, 102, 241, 0.25);
}

.mobile-nav-link-promo:hover {
  background: linear-gradient(135deg, #4F46E5 0%, #7C3AED 100%) !important;
  color: #FFFFFF !important;
}

/* Footer promo link highlight */
.footer-link-promo {
  color: var(--color-primary) !important;
  font-weight: 700 !important;
}

.footer-link-promo:hover {
  color: var(--color-primary-hover) !important;
  background: rgba(0, 102, 255, 0.08) !important;
}