/* ========================================
   广州链天下科技有限公司 - 官方网站样式
   Design System & Variables
   ======================================== */

:root {
  /* Color Palette */
  --color-primary: #0d47a1;
  --color-primary-dark: #082e6a;
  --color-primary-light: #1565c0;
  --color-accent: #2196f3;
  --color-accent-light: #64b5f6;
  
  /* Neutral Colors */
  --color-dark: #0a1628;
  --color-text: #1a1a2e;
  --color-text-secondary: #4a5568;
  --color-text-muted: #718096;
  --color-border: #e2e8f0;
  --color-bg: #ffffff;
  --color-bg-alt: #f7fafc;
  --color-bg-dark: #f1f5f9;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #0d47a1 0%, #1565c0 50%, #1976d2 100%);
  --gradient-hero: linear-gradient(135deg, rgba(10, 22, 40, 0.92) 0%, rgba(13, 71, 161, 0.85) 100%);
  --gradient-card: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
  
  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 10px 30px rgba(13, 71, 161, 0.1);
  --shadow-xl: 0 20px 50px rgba(13, 71, 161, 0.15);
  
  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  --space-4xl: 8rem;
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 2rem;
  --font-size-4xl: 2.5rem;
  --font-size-5xl: 3.5rem;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;
  
  /* Transitions */
  --transition-fast: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-base: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
  
  /* Layout */
  --container-max: 1200px;
  --header-height: 72px;
}

/* ========================================
   Reset & Base
   ======================================== */

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

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

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
  list-style: none;
}

/* ========================================
   Layout Utilities
   ======================================== */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

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

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

.section-title {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
  position: relative;
}

.section-title::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: var(--gradient-primary);
  margin: var(--space-md) auto 0;
  border-radius: var(--radius-full);
}

.section-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ========================================
   Header & Navigation
   ======================================== */

.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: var(--transition-base);
}

.header.scrolled {
  box-shadow: var(--shadow-md);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.logo-icon {
  width: 36px;
  height: 36px;
  background: var(--gradient-primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.logo-icon svg {
  width: 20px;
  height: 20px;
  fill: none;
  stroke: white;
  stroke-width: 2;
}

.logo-text {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-primary);
}

.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-xl);
}

.nav-link {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  position: relative;
  padding: var(--space-xs) 0;
}

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

.nav-link:hover {
  color: var(--color-primary);
}

.nav-link:hover::after {
  width: 100%;
}

.nav-link.active {
  color: var(--color-primary);
}

.nav-link.active::after {
  width: 100%;
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-xs);
}

.mobile-menu-btn span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  margin: 6px 0;
  transition: var(--transition-fast);
  border-radius: var(--radius-full);
}

/* ========================================
   Hero Section
   ======================================== */

.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  overflow: hidden;
  padding-top: var(--header-height);
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: -2;
}

.hero-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--gradient-hero);
}

.hero .container {
  position: relative;
  z-index: 1;
}

.hero-content {
  max-width: 680px;
  color: white;
  padding: var(--space-3xl) 0;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 6px 16px;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-full);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-lg);
  backdrop-filter: blur(4px);
}

.hero-badge-dot {
  width: 6px;
  height: 6px;
  background: #4ade80;
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

.hero-title {
  font-size: var(--font-size-5xl);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: var(--space-lg);
  letter-spacing: -0.02em;
}

.hero-title-highlight {
  background: linear-gradient(135deg, #64b5f6, #42a5f5);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  font-size: var(--font-size-lg);
  line-height: 1.7;
  opacity: 0.9;
  margin-bottom: var(--space-xl);
  max-width: 540px;
}

.hero-actions {
  display: flex;
  gap: var(--space-md);
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: 12px 28px;
  font-size: var(--font-size-sm);
  font-weight: 600;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: var(--transition-base);
  text-decoration: none;
}

.btn-primary {
  background: white;
  color: var(--color-primary);
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-outline {
  background: transparent;
  color: white;
  border: 1px solid rgba(255, 255, 255, 0.4);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.6);
}

.btn-blue {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-blue:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

/* Hero Stats */
.hero-stats {
  display: flex;
  gap: var(--space-2xl);
  margin-top: var(--space-3xl);
  padding-top: var(--space-xl);
  border-top: 1px solid rgba(255, 255, 255, 0.15);
}

.hero-stat-number {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  margin-bottom: 4px;
}

.hero-stat-label {
  font-size: var(--font-size-sm);
  opacity: 0.7;
}

/* ========================================
   About Section
   ======================================== */

.about {
  background: var(--color-bg);
}

.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: center;
}

.about-image {
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-xl);
}

.about-image img {
  width: 100%;
  height: auto;
  transition: var(--transition-slow);
}

.about-image:hover img {
  transform: scale(1.02);
}

.about-content h2 {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

.about-content h2::after {
  content: '';
  display: block;
  width: 48px;
  height: 3px;
  background: var(--gradient-primary);
  margin-top: var(--space-sm);
  border-radius: var(--radius-full);
}

.about-desc {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: var(--space-lg);
}

.about-features {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.about-feature {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.about-feature-icon {
  width: 32px;
  height: 32px;
  background: rgba(13, 71, 161, 0.08);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.about-feature-icon svg {
  width: 16px;
  height: 16px;
  stroke: var(--color-primary);
  fill: none;
  stroke-width: 2;
}

.about-feature-text {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text);
}

/* ========================================
   Services Section
   ======================================== */

.services {
  background: var(--color-bg-alt);
}

.services-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-xl);
}

.service-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  border: 1px solid var(--color-border);
  transition: var(--transition-base);
  position: relative;
  overflow: hidden;
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
  transform: scaleX(0);
  transform-origin: left;
  transition: var(--transition-base);
}

.service-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-xl);
  border-color: transparent;
}

.service-card:hover::before {
  transform: scaleX(1);
}

.service-card-image {
  width: 100%;
  height: 200px;
  border-radius: var(--radius-md);
  overflow: hidden;
  margin-bottom: var(--space-lg);
}

.service-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.service-card-icon {
  width: 56px;
  height: 56px;
  background: rgba(13, 71, 161, 0.06);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
}

.service-card-icon svg {
  width: 28px;
  height: 28px;
  stroke: var(--color-primary);
  fill: none;
  stroke-width: 1.5;
}

.service-card-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
}

.service-card-desc {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-md);
}

.service-card-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
}

.service-card-list li {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
}

.service-card-list li::before {
  content: '';
  width: 5px;
  height: 5px;
  background: var(--color-accent);
  border-radius: 50%;
  flex-shrink: 0;
}

/* ========================================
   Cases Section
   ======================================== */

.cases {
  background: var(--color-bg);
}

.cases-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
}

.case-card {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  overflow: hidden;
  transition: var(--transition-base);
}

.case-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.case-card-header {
  padding: var(--space-lg) var(--space-lg) 0;
}

.case-card-tag {
  display: inline-block;
  padding: 4px 12px;
  background: rgba(13, 71, 161, 0.06);
  color: var(--color-primary);
  font-size: var(--font-size-xs);
  font-weight: 600;
  border-radius: var(--radius-full);
  margin-bottom: var(--space-sm);
}

.case-card-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.case-card-desc {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.6;
  padding: var(--space-sm) var(--space-lg) var(--space-lg);
}

.case-card-footer {
  padding: 0 var(--space-lg) var(--space-lg);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.case-tech-tag {
  padding: 3px 10px;
  background: var(--color-bg-alt);
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
}

/* ========================================
   Contact Section
   ======================================== */

.contact {
  background: var(--color-bg-alt);
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
}

.contact-info h3 {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-md);
}

.contact-info-desc {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-xl);
}

.contact-items {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.contact-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
}

.contact-item-icon {
  width: 44px;
  height: 44px;
  background: rgba(13, 71, 161, 0.06);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.contact-item-icon svg {
  width: 20px;
  height: 20px;
  stroke: var(--color-primary);
  fill: none;
  stroke-width: 2;
}

.contact-item-label {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-bottom: 2px;
}

.contact-item-value {
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--color-text);
}

/* Contact Form */
.contact-form {
  background: var(--color-bg);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--color-border);
}

.form-group {
  margin-bottom: var(--space-md);
}

.form-label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 6px;
}

.form-input,
.form-textarea {
  width: 100%;
  padding: 12px 16px;
  font-size: var(--font-size-sm);
  font-family: var(--font-family);
  color: var(--color-text);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: var(--transition-fast);
  outline: none;
}

.form-input:focus,
.form-textarea:focus {
  border-color: var(--color-accent);
  box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.1);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.form-submit {
  width: 100%;
  padding: 14px;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: white;
  background: var(--gradient-primary);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: var(--transition-base);
}

.form-submit:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-lg);
}

/* ========================================
   Footer
   ======================================== */

.footer {
  background: var(--color-dark);
  color: rgba(255, 255, 255, 0.7);
  padding: var(--space-3xl) 0 var(--space-lg);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer-brand-desc {
  font-size: var(--font-size-sm);
  line-height: 1.7;
  margin-top: var(--space-md);
  opacity: 0.8;
}

.footer-col-title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: white;
  margin-bottom: var(--space-md);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.footer-link {
  font-size: var(--font-size-sm);
  opacity: 0.7;
  transition: var(--transition-fast);
}

.footer-link:hover {
  opacity: 1;
  color: var(--color-accent-light);
}

.footer-bottom {
  padding-top: var(--space-lg);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: var(--font-size-xs);
  opacity: 0.6;
}

.footer-icp a {
  color: rgba(255, 255, 255, 0.6);
  transition: var(--transition-fast);
}

.footer-icp a:hover {
  color: rgba(255, 255, 255, 0.9);
}

/* ========================================
   Animations
   ======================================== */

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.animate-on-scroll {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 1024px) {
  .hero-title {
    font-size: var(--font-size-4xl);
  }
  
  .services-grid {
    grid-template-columns: 1fr;
  }
  
  .cases-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-xl);
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: 64px;
  }
  
  .nav-list {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: white;
    flex-direction: column;
    padding: var(--space-lg);
    gap: var(--space-md);
    box-shadow: var(--shadow-lg);
    border-top: 1px solid var(--color-border);
  }
  
  .nav-list.active {
    display: flex;
  }
  
  .mobile-menu-btn {
    display: block;
  }
  
  .mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  
  .mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
  }
  
  .mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
  }
  
  .hero-title {
    font-size: var(--font-size-3xl);
  }
  
  .hero-desc {
    font-size: var(--font-size-base);
  }
  
  .hero-stats {
    gap: var(--space-lg);
  }
  
  .hero-stat-number {
    font-size: var(--font-size-2xl);
  }
  
  .about-grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .about-image {
    order: -1;
  }
  
  .about-features {
    grid-template-columns: 1fr;
  }
  
  .cases-grid {
    grid-template-columns: 1fr;
  }
  
  .contact-grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .footer-grid {
    grid-template-columns: 1fr;
    gap: var(--space-xl);
  }
  
  .footer-bottom {
    flex-direction: column;
    gap: var(--space-sm);
    text-align: center;
  }
  
  .section {
    padding: var(--space-3xl) 0;
  }
  
  .section-title {
    font-size: var(--font-size-2xl);
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: var(--font-size-2xl);
  }
  
  .hero-actions {
    flex-direction: column;
  }
  
  .hero-stats {
    flex-direction: column;
    gap: var(--space-md);
  }
  
  .btn {
    width: 100%;
    justify-content: center;
  }
}