/* ============================================================
   东交智控 - Design System
   浅色商务蓝白风 · BIM+GIS+AI+IoT 工程数字化平台
   ============================================================ */

:root {
  /* === Brand Colors === */
  --c-primary: #1a56db;
  --c-primary-dark: #1342a8;
  --c-primary-light: #3b82f6;
  --c-secondary: #0ea5e9;
  --c-accent: #0ea5e9;
  --c-accent-light: #e0f2fe;
  --c-gradient-primary: linear-gradient(135deg, #1a56db 0%, #0ea5e9 100%);
  --c-gradient-accent: linear-gradient(135deg, #1a56db 0%, #0ea5e9 100%);
  --c-gradient-hero: linear-gradient(135deg, rgba(15,23,42,0.85) 0%, rgba(26,86,219,0.6) 50%, rgba(14,165,233,0.4) 100%);

  /* === Background === */
  --bg-darkest: #0f172a;
  --bg-dark: #0f172a;
  --bg-body: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #f8fafc;
  --bg-elevated: #ffffff;
  --bg-overlay: rgba(15, 23, 42, 0.85);
  --bg-glass: rgba(255, 255, 255, 0.8);
  --bg-glass-hover: rgba(248, 250, 252, 0.9);
  --bg-gray: #f8fafc;

  /* === Text === */
  --text-primary: #111827;
  --text-secondary: #374151;
  --text-muted: #6b7280;
  --text-light: #9ca3af;
  --text-accent: #1a56db;

  /* === Border === */
  --border-subtle: rgba(0, 0, 0, 0.05);
  --border-default: #e5e7eb;
  --border-glow: rgba(26, 86, 219, 0.3);

  /* === Shadows === */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 4px 16px rgba(26, 86, 219, 0.15);
  --shadow-glow-strong: 0 8px 24px rgba(26, 86, 219, 0.25);

  /* === Typography === */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 1.875rem;
  --fs-4xl: 2.25rem;
  --fs-5xl: 3rem;
  --fs-6xl: 3.75rem;

  /* === Spacing === */
  --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;
  --space-5xl: 8rem;

  /* === Layout === */
  --container-max: 1280px;
  --header-height: 72px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;

  /* === Transitions === */
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--header-height);
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

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

a:hover {
  color: var(--c-primary-light);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
}

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

/* === Section === */
.section {
  padding: var(--space-4xl) 0;
  position: relative;
}

.section-sm {
  padding: var(--space-2xl) 0;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section-eyebrow {
  display: inline-block;
  font-size: var(--fs-sm);
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--c-primary);
  margin-bottom: var(--space-md);
  padding: 4px 16px;
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-full);
  background: var(--c-accent-light);
}

.section-title {
  font-size: var(--fs-4xl);
  font-weight: 700;
  margin-bottom: var(--space-md);
  background: var(--c-gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.section-subtitle {
  font-size: var(--fs-lg);
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto;
}

/* === Buttons === */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-size: var(--fs-base);
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
  white-space: nowrap;
  cursor: pointer;
}

.btn-primary {
  background: var(--c-gradient-primary);
  color: #fff;
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow-strong);
  color: #fff;
}

.btn-outline {
  border: 1px solid var(--border-default);
  color: var(--text-primary);
  background: var(--bg-glass);
  backdrop-filter: blur(10px);
}

.btn-outline:hover {
  border-color: var(--c-primary);
  background: var(--c-accent-light);
  color: var(--c-primary);
}

.btn-ghost {
  color: var(--text-secondary);
  padding: 8px 16px;
}

/* === Scroll Indicator (右侧竖排) === */
.scroll-indicator {
  position: absolute;
  right: 32px;
  bottom: 40px;
  z-index: 5;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  color: rgba(255, 255, 255, 0.45);
  text-decoration: none;
  transition: color 0.3s ease, opacity 0.4s ease, visibility 0.4s ease;
  opacity: 1;
}

.scroll-indicator.is-hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.scroll-indicator:hover {
  color: var(--c-primary);
}

.scroll-indicator-text {
  writing-mode: vertical-rl;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: inherit;
  transition: color 0.3s ease;
}

.scroll-indicator-line {
  position: relative;
  width: 1px;
  height: 60px;
  background: rgba(255, 255, 255, 0.2);
  overflow: hidden;
}

.scroll-indicator-line-fill {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 24px;
  background: linear-gradient(180deg, transparent 0%, var(--c-primary) 100%);
  animation: scroll-line-drop 2.2s ease-in-out infinite;
}

.scroll-indicator-arrow {
  color: inherit;
  transition: color 0.3s ease;
  animation: scroll-arrow-bounce 2.2s ease-in-out infinite;
}

@keyframes scroll-line-drop {
  0% { top: -24px; opacity: 0; }
  20% { opacity: 1; }
  80% { top: 60px; opacity: 0; }
  100% { top: 60px; opacity: 0; }
}

@keyframes scroll-arrow-bounce {
  0%, 100% { transform: translateY(-3px); opacity: 0.5; }
  50% { transform: translateY(3px); opacity: 1; }
}

@media (max-width: 768px) {
  .scroll-indicator { right: 16px; bottom: 24px; }
  .scroll-indicator-line { height: 40px; }
}

.btn-ghost:hover {
  color: var(--c-primary);
}

.btn-lg {
  padding: 16px 36px;
  font-size: var(--fs-lg);
}

/* === Card === */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.card:hover {
  border-color: var(--border-glow);
  background: var(--bg-card-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.card-glow::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--c-gradient-primary);
  opacity: 0;
  transition: opacity var(--transition-base);
}

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

/* === Glass Card === */
.glass {
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
}

/* === Grid === */
.grid {
  display: grid;
  gap: var(--space-xl);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* === Badge === */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 4px 12px;
  font-size: var(--fs-xs);
  font-weight: 600;
  border-radius: var(--radius-full);
  background: var(--c-accent-light);
  color: var(--c-primary);
  border: 1px solid rgba(26, 86, 219, 0.2);
}

.badge-accent {
  background: var(--c-accent-light);
  color: var(--c-accent);
  border-color: rgba(14, 165, 233, 0.2);
}

/* === Background Effects === */
.bg-grid {
  background-image:
    linear-gradient(rgba(0, 0, 0, 0.02) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 0, 0, 0.02) 1px, transparent 1px);
  background-size: 40px 40px;
}

.bg-glow {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.15;
  pointer-events: none;
  z-index: 0;
}

.bg-glow-blue {
  background: var(--c-primary);
}

.bg-glow-purple {
  background: var(--c-accent);
}

/* === Text Utilities === */
.text-gradient {
  background: var(--c-gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

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