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

body {
    font-family: 'Microsoft YaHei Light', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fff;
}

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

/* 卡片式布局 */
.card {
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0 8px 12px rgba(0, 0, 0, 0.08);
    padding: 30px;
    margin-bottom: 30px;
}

/* 导航栏样式 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo a {
    font-size: 24px;
    font-weight: 700;
    color: #333;
    text-decoration: none;
}

.main-nav ul {
    display: flex;
    list-style: none;
}

.main-nav li {
    margin-left: 30px;
    position: relative;
}

.main-nav a {
    text-decoration: none;
    color: #333;
    font-weight: 500;
    padding: 10px 0;
    display: block;
}

/* 首屏视频背景 */
.hero {
    position: relative;
    height: 100vh;
    overflow: hidden;
    background-color: #333;
}

.hero-content {
    position: absolute;
    bottom: 50px;
    left: 50px;
    z-index: 2;
}

.slogan {
    font-size: 48px;
    font-weight: 700;
    color: #fff;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
    line-height: 1.3;
}

/* 页面标题 */
.page-header {
    background-color: #333;
    color: #fff;
    padding: 100px 0 60px;
    margin-top: 70px;
    text-align: center;
}

/* 章节样式 */
.section {
    padding: 60px 0;
}

.section-title {
    font-size: 28px;
    font-weight: 700;
    color: #333;
    margin-bottom: 30px;
    text-align: center;
}

/* 页脚 */
.footer {
    background-color: #fff;
    color: #000;
    padding: 30px 0;
    text-align: center;
}

/* 返回顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: #333;
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 24px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 999;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}