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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: #333;
  background: #f5f5f5;
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* 导航栏 */
nav {
  background: #2c3e50;
  padding: 1rem 2rem;
  display: flex;
  gap: 1.5rem;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

nav a {
  color: #bdc3c7;
  text-decoration: none;
  font-weight: 500;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  transition: color 0.2s, background 0.2s;
}

nav a:hover {
  color: #fff;
  background: rgba(255, 255, 255, 0.1);
}

nav a.active {
  color: #fff;
  background: #3498db;
}

/* 主体 */
main {
  flex: 1;
  max-width: 800px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1rem;
}

.hero {
  text-align: center;
  padding: 3rem 0 2rem;
}

.hero h1 {
  font-size: 2.5rem;
  color: #2c3e50;
  margin-bottom: 0.5rem;
}

.hero p {
  font-size: 1.1rem;
  color: #7f8c8d;
}

/* 卡片 */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-top: 1rem;
}

.card {
  background: #fff;
  padding: 2rem 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
  text-align: center;
}

.card h3 {
  color: #3498db;
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
}

.card p {
  color: #666;
  font-size: 0.95rem;
}

/* 内容区 */
.content {
  background: #fff;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.06);
}

.content h2 {
  color: #2c3e50;
  margin: 1.5rem 0 0.75rem;
}

.content h2:first-child {
  margin-top: 0;
}

.content p, .content li {
  color: #555;
}

.content ul {
  padding-left: 1.5rem;
}

.content li {
  margin-bottom: 0.25rem;
}

/* 表格 */
table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 0.5rem;
}

th, td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid #eee;
}

th {
  background: #f8f9fa;
  color: #2c3e50;
  font-weight: 600;
}

/* 表单 */
.contact-form {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.contact-form label {
  font-weight: 600;
  color: #2c3e50;
}

.contact-form input,
.contact-form textarea {
  padding: 0.75rem;
  border: 1px solid #ddd;
  border-radius: 6px;
  font-size: 1rem;
  font-family: inherit;
  transition: border-color 0.2s;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: #3498db;
  box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.15);
}

.contact-form button {
  padding: 0.75rem 2rem;
  background: #3498db;
  color: #fff;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s;
  align-self: flex-start;
}

.contact-form button:hover {
  background: #2980b9;
}

.contact-info {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid #eee;
}

.contact-info h3 {
  color: #2c3e50;
  margin-bottom: 0.5rem;
}

.contact-info p {
  color: #666;
  margin-bottom: 0.25rem;
}

/* 页脚 */
footer {
  text-align: center;
  padding: 1.5rem;
  color: #999;
  font-size: 0.9rem;
  border-top: 1px solid #e0e0e0;
  margin-top: 2rem;
}

/* 响应式 */
@media (max-width: 600px) {
  .hero h1 {
    font-size: 1.8rem;
  }

  .cards {
    grid-template-columns: 1fr;
  }

  nav {
    padding: 0.75rem 1rem;
    gap: 0.75rem;
  }
}