/* 基础样式 - 内页使用 */

/* 重置样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
    overflow-x: hidden;
}

a {
    text-decoration: none;
    color: inherit;
}

ul, ol {
    list-style: none;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button {
    font-family: inherit;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ==================== 头部导航 ==================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 80px;
    background-color: #fff;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    z-index: 1000;
    transition: all 0.3s ease;
}

.header-container {
    max-width: 1920px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 60px;
    height: 80px;
}

.logo img {
    height: 55px;
    width: auto;
}

/* 主导航 */
.main-nav {
    display: flex;
}

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

.nav-item {
    position: relative;
}

.nav-item > a {
    display: block;
    padding: 28px 25px;
    font-size: 17px;
    color: #333;
    transition: color 0.3s ease;
}

.nav-item:hover > a,
.nav-item.active > a {
    color: #1e88e5;
}

/* 下拉菜单 */
.dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 150px;
    background-color: #fff;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all 0.3s ease;
    z-index: 100;
}

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

.dropdown li a {
    display: block;
    padding: 12px 20px;
    font-size: 14px;
    color: #666;
    transition: all 0.3s ease;
}

.dropdown li a:hover {
    background-color: #f5f5f5;
    color: #1e88e5;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: space-between;
    width: 28px;
    height: 20px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
}

.mobile-menu-btn span {
    display: block;
    width: 100%;
    height: 3px;
    background-color: #333;
    border-radius: 2px;
    transition: all 0.3s ease;
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: translateY(8.5px) rotate(45deg);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: translateY(-8.5px) rotate(-45deg);
}

/* ==================== 响应式 ==================== */
@media screen and (max-width: 1200px) {
    .header-container {
        padding: 0 30px;
    }
    
    .nav-item > a {
        padding: 28px 18px;
        font-size: 15px;
    }
}

@media screen and (max-width: 992px) {
    .header-container {
        padding: 0 20px;
    }
    
    .main-nav {
        display: none;
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background-color: #fff;
        box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
        z-index: 1000;
    }
    
    .main-nav.active {
        display: block;
    }
    
    .nav-list {
        flex-direction: column;
        align-items: stretch;
    }
    
    .nav-item > a {
        padding: 15px 20px;
        border-bottom: 1px solid #eee;
    }
    
    .dropdown {
        position: static;
        box-shadow: none;
        opacity: 1;
        visibility: visible;
        transform: none;
        background-color: #f9f9f9;
        display: none;
    }
    
    .has-dropdown .dropdown {
        display: none;
    }
    
    .dropdown li a {
        padding-left: 40px;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .mobile-menu-btn.active span:nth-child(1) {
        transform: translateY(8.5px) rotate(45deg);
    }
    
    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-btn.active span:nth-child(3) {
        transform: translateY(-8.5px) rotate(-45deg);
    }
}

@media screen and (max-width: 768px) {
    .header {
        height: 60px;
    }
    
    .header-container {
        height: 60px;
        padding: 0 15px;
    }
    
    .logo img {
        height: 35px;
    }
    
    .main-nav {
        top: 60px;
    }
    
    .nav-item > a {
        padding: 12px 15px;
        font-size: 14px;
    }
    
    .dropdown li a {
        padding: 10px 15px 10px 30px;
        font-size: 13px;
    }
}