/* 不变的头部和尾部CSS */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

:root {
    --primary-color: #4a6fa5;
    --secondary-color: #6b8cbc;
    --accent-color: #ff7e5f;
    --text-color: #333;
    --light-text: #666;
    --lighter-text: #888;
    --bg-color: #f8f9fa;
    --card-bg: #ffffff;
    --border-color: #eaeaea;
    --shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 10px 25px rgba(0, 0, 0, 0.08);
    --transition: all 0.3s ease;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    width: 100%;
    max-width: 1680px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 头部样式 - 保持不变 */
header {
    background-color: var(--card-bg);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    width: 100%;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 10px;
}

.logo i {
    color: var(--accent-color);
}

nav {
    display: flex;
    align-items: center;
}

.nav-main {
    display: flex;
    list-style: none;
    gap: 30px;
    margin-right: 20px;
}

nav a {
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    padding: 5px 0;
    position: relative;
    display: flex;
    align-items: center;
}

nav a:hover {
    color: var(--primary-color);
}

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

nav a:hover::after {
    width: 100%;
}

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

/* 下拉菜单样式 - 保持不变 */
.dropdown {
    position: relative;
}

.dropdown-btn {
    background: none;
    border: none;
    color: var(--text-color);
    font-weight: 500;
    cursor: pointer;
    padding: 5px 15px;
    border-radius: 5px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 5px;
}

.dropdown-btn:hover {
    background-color: rgba(74, 111, 165, 0.1);
    color: var(--primary-color);
}

.dropdown-btn i {
    font-size: 0.8rem;
    transition: var(--transition);
}

.dropdown-btn.active i {
    transform: rotate(180deg);
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    background-color: var(--card-bg);
    box-shadow: var(--shadow-hover);
    border-radius: 8px;
    min-width: 180px;
    padding: 10px 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: var(--transition);
    z-index: 1000;
}

.dropdown-menu.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: 10px 20px;
    color: var(--text-color);
    text-decoration: none;
    transition: var(--transition);
}

.dropdown-menu a:hover {
    background-color: rgba(74, 111, 165, 0.05);
    color: var(--primary-color);
    padding-left: 25px;
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--primary-color);
    cursor: pointer;
}

.tag {
    background-color: #f0f4ff;
    color: var(--primary-color);
    padding: 4px 10px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
    text-decoration: none;
    transition: var(--transition);
}

.tag:hover {
    background-color: var(--primary-color);
    color: white;
}

/* 页脚样式 - 保持不变 */
footer {
    background-color: var(--text-color);
    color: #ddd;
    padding: 50px 0 20px;
    width: 100%;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section {
    flex: 1;
    min-width: 250px;
}

.footer-section h3 {
    color: white;
    font-size: 1.3rem;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--accent-color);
}

.footer-section p {
    margin-bottom: 20px;
    line-height: 1.7;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 10px;
}

.footer-links a {
    color: #bbb;
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
}

.social-links {
    display: flex;
    gap: 15px;
    margin-top: 20px;
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    color: white;
    text-decoration: none;
    transition: var(--transition);
}

.social-links a:hover {
    background-color: var(--accent-color);
    transform: translateY(-3px);
}

.copyright, .copyright a {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: #aaa;
    font-size: 0.9rem;
}

/* 响应式设计 - 头部和尾部部分保持不变 */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        align-items: flex-start;
        padding: 15px 0;
    }

    .logo {
        margin-bottom: 15px;
    }

    nav {
        width: 100%;
        justify-content: space-between;
    }

    .nav-main {
        display: none;
    }

    .nav-main.active {
        display: flex;
        flex-direction: column;
        width: 100%;
        gap: 0;
        margin: 15px 0;
    }

    .nav-main li {
        width: 100%;
        padding: 10px 0;
        border-bottom: 1px solid var(--border-color);
    }

    .dropdown {
        width: 100%;
    }

    .dropdown-btn {
        width: 100%;
        justify-content: space-between;
    }

    .dropdown-menu {
        position: static;
        width: 100%;
        box-shadow: none;
        border-radius: 0;
        opacity: 1;
        visibility: visible;
        transform: none;
        display: none;
        padding-left: 20px;
    }

    .dropdown-menu.active {
        display: block;
    }

    .mobile-menu-btn {
        display: block;
        position: absolute;
        top: 20px;
        right: 20px;
    }

    .footer-content {
        flex-direction: column;
        gap: 30px;
    }
}