/* ===== 导航栏 ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: white;
  box-shadow: var(--shadow-sm);
  z-index: 1000;
  height: 70px;
}

.navbar-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-brand {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-primary);
}

.navbar-links {
  display: flex;
  gap: var(--spacing-lg);
  align-items: center;
}

.navbar-links a {
  color: var(--color-text);
  font-weight: 500;
  padding: 8px 0;
  position: relative;
}

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

.navbar-links a:hover::after,
.navbar-links a.active::after {
  width: 100%;
}

.navbar-links a:hover {
  color: var(--color-primary);
}

/* ===== 页脚 ===== */
.footer {
  background: #1e293b;
  color: white;
  padding: var(--spacing-xxl) 0;
  margin-top: var(--spacing-xxl);
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-xl);
}

.footer-section h3 {
  margin-bottom: var(--spacing-md);
  color: white;
}

.footer-section a {
  display: block;
  color: #9ca3af;
  padding: 4px 0;
}

.footer-section a:hover {
  color: white;
}

.footer-bottom {
  text-align: center;
  padding-top: var(--spacing-lg);
  margin-top: var(--spacing-lg);
  border-top: 1px solid #374151;
  color: #9ca3af;
}

/* ===== 主内容区 ===== */
main {
  margin-top: 70px;
  min-height: calc(100vh - 70px);
}

/* ===== 区块 ===== */
.section {
  padding: var(--spacing-xxl) 0;
}

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

/* ===== 网格 ===== */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

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

@media (max-width: 768px) {
  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }
}