/* 网站全局样式 */
* { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: "微软雅黑", "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #f8f9fa;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏样式 */
.navbar {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.8rem;
    font-weight: bold;
}

.nav-links a {
    color: white;
    text-decoration: none;
    margin-left: 25px;
    font-size: 1.1rem;
    transition: opacity 0.3s;
}

.nav-links a:hover {
    opacity: 0.8;
}

/* 页头 */
.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 60px 0;
    text-align: center;
    margin-bottom: 40px;
}

.header h1 {
    font-size: 3rem;
    margin-bottom: 15px;
}

.header p {
    font-size: 1.3rem;
    max-width: 800px;
    margin: 0 auto;
}

/* 分类导航卡片 */
.category-nav {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin: 40px 0;
}

.category-card {
    background: white;
    border-radius: 15px;
    padding: 25px;
    text-align: center;
    box-shadow: 0 5px 15px rgba(0,0,0,0.08);
    transition: transform 0.3s, box-shadow 0.3s;
    text-decoration: none;
    color: inherit;
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

.category-card i {
    font-size: 2.5rem;
    margin-bottom: 15px;
    color: #667eea;
}

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 10px;
    color: #333;
}

/* 术语卡片 */
.term-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
    margin: 40px 0;
}

.term-card {
    background: white;
    border-radius: 12px;
    padding: 25px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    transition: all 0.3s;
}

.term-card:hover {
    box-shadow: 0 8px 20px rgba(0,0,0,0.12);
}

.term-card h3 {
    font-size: 1.6rem;
    color: #667eea;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 2px solid #f0f0f0;
}

.term-card p {
    color: #666;
    margin-bottom: 10px;
    font-size: 1.05rem;
}

/* 页脚 */
.footer {
    background: #2c3e50;
    color: white;
    padding: 40px 0;
    margin-top: 60px;
}

.footer .container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.footer h4 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: #ecf0f1;
}

.footer a {
    color: #bdc3c7;
    text-decoration: none;
    display: block;
    margin-bottom: 8px;
}

.footer a:hover {
    color: white;
}

.copyright {
    text-align: center;
    padding-top: 30px;
    margin-top: 30px;
    border-top: 1px solid #34495e;
    color: #95a5a6;
    font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header h1 { font-size: 2.2rem; }
    .header p { font-size: 1.1rem; }
    .nav-links a { margin-left: 15px; }
}