:root {
  --color-primary: #2c3e50;
  --color-secondary: #34495e;
  --color-accent: #8b4513;
  --color-background: #f8f9fa;
  --color-surface: #ffffff;
  --color-text: #2c3e50;
  --color-text-muted: #7f8c8d;
  --color-border: #e9ecef;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 3rem;
  --spacing-xl: 4rem;
  --border-radius: 4px;
  --transition: all 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-background);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-sm);
}

/* Navigation */
nav {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-sm) 0;
}

.nav-logo {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
  letter-spacing: 1px;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-lg);
}

.nav-link {
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

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

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width 0.3s ease;
}

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

/* Typography */
h1, h2, h3 {
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: var(--spacing-sm);
  color: var(--color-primary);
}

h1 {
  font-size: 2.5rem;
}

h2 {
  font-size: 2rem;
}

h3 {
  font-size: 1.5rem;
}

p {
  margin-bottom: var(--spacing-sm);
  color: var(--color-text);
  max-width: 800px;
}

/* Images */
img {
  max-width: 100%;
  height: auto;
  display: block;
  transition: transform 0.5s ease;
}

img:hover {
  transform: scale(1.02);
}

.image-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-md);
  margin: var(--spacing-md) 0;
}

.image-card {
  overflow: hidden;
  border-radius: var(--border-radius);
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

/* Hero Section */
.hero {
  padding: var(--spacing-xl) 0;
  text-align: center;
}

.hero-content {
  margin-bottom: var(--spacing-lg);
}

.hero-image {
  width: 100%;
  height: 60vh;
  object-fit: cover;
  border-radius: var(--border-radius);
}

/* Content Sections */
.section {
  padding: var(--spacing-lg) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-lg);
}

/* Cards */
.card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: var(--transition);
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-md);
  margin: var(--spacing-md) 0;
}

/* Footer */
footer {
  background: var(--color-primary);
  color: var(--color-surface);
  text-align: center;
  padding: var(--spacing-md) 0;
  margin-top: var(--spacing-xl);
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    gap: var(--spacing-sm);
  }
  
  .nav-link {
    font-size: 0.9rem;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.5rem;
  }
  
  .hero-image {
    height: 40vh;
  }
  
  .container {
    padding: 0 var(--spacing-xs);
  }
}

@media (max-width: 480px) {
  .nav-container {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
  
  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
  }
  
  h1 {
    font-size: 1.75rem;
  }
  
  h2 {
    font-size: 1.25rem;
  }
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

/* Utility Classes */
.text-center {
  text-align: center;
}

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

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-xs); }
.mb-2 { margin-bottom: var(--spacing-sm); }
.mb-3 { margin-bottom: var(--spacing-md); }
.mb-4 { margin-bottom: var(--spacing-lg); }
.mb-5 { margin-bottom: var(--spacing-xl); }