/* 公共样式文件 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #1e3a8a;
    --secondary-color: #3b82f6;
    --accent-color: #f59e0b;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f9fafb;
    --white: #ffffff;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

body {
    font-family: 'Microsoft YaHei', 'PingFang SC', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--white);
}

/* 导航栏样式 */
.navbar {
    background-color: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 1rem 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem 0 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo a {
    text-decoration: none;
    color: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: flex-start;
}

.logo-img {
    height: 60px;
    width: auto;
    max-width: 250px;
    object-fit: contain;
    transition: transform 0.3s ease, opacity 0.3s ease;
    display: block;
}

.logo-img:hover {
    transform: scale(1.05);
    opacity: 0.9;
}

/* Logo图片加载失败时的降级处理 */
.logo-img:not([src]),
.logo-img[src=""],
.logo-img[src*="undefined"] {
    display: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
    padding: 0.5rem 0;
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.nav-toggle .bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    transition: 0.3s;
}

/* 移动端导航样式 */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-logo a {
        justify-content: flex-start;
    }

    .logo-img {
        height: 45px;
        max-width: 180px;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--white);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow);
        padding: 2rem 0;
        gap: 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .nav-item {
        width: 100%;
        padding: 1rem 0;
    }

    .nav-toggle.active .bar:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active .bar:nth-child(1) {
        transform: translateY(7px) rotate(45deg);
    }

    .nav-toggle.active .bar:nth-child(3) {
        transform: translateY(-7px) rotate(-45deg);
    }
}

/* 通用容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* 页面标题 */
.page-header {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--white);
    padding: 4rem 0;
    text-align: center;
}

.page-header h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.page-header p {
    font-size: 1.2rem;
    opacity: 0.9;
}

/* 内容区域 */
.content-section {
    padding: 4rem 0;
}

.section-title {
    text-align: center;
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 3rem;
    position: relative;
    padding-bottom: 1rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 3px;
    background-color: var(--accent-color);
}

/* 卡片样式 */
.card {
    background: var(--white);
    border-radius: 8px;
    box-shadow: var(--shadow);
    padding: 2rem;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    background-color: var(--primary-color);
    color: var(--white);
    text-decoration: none;
    border-radius: 5px;
    transition: background-color 0.3s ease;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.btn:hover {
    background-color: var(--secondary-color);
}

.btn-secondary {
    background-color: var(--accent-color);
}

.btn-secondary:hover {
    background-color: #d97706;
}

/* 页脚 */
.footer {
    background-color: var(--text-dark);
    color: var(--white);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: var(--accent-color);
}

.footer-section p,
.footer-section a {
    color: #d1d5db;
    text-decoration: none;
    line-height: 2;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: #9ca3af;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .page-header h1 {
        font-size: 2rem;
    }

    .page-header p {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.5rem;
    }

    .content-section {
        padding: 2rem 0;
    }

    .container {
        padding: 0 1rem;
    }
}

/* 网格布局 */
.grid {
    display: grid;
    gap: 2rem;
}

.grid-2 {
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-3 {
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
}

.grid-4 {
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
}

/* 文本工具类 */
.text-center {
    text-align: center;
}

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

.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mt-3 { margin-top: 3rem; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mb-3 { margin-bottom: 3rem; }