/* 基础样式设置 */
body {
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif; /* 使用现代无衬线字体 */
    background: linear-gradient(135deg, #1E3C72, #2A5298); /* 主色调渐变背景 */
    color: #FFFFFF;
}

/* 导航栏样式 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: linear-gradient(90deg, #2A5298, #1E3C72);
    display: flex;
    justify-content: space-around;
    align-items: center;
    padding: 15px 0;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    transition: top 0.3s;
}

.navbar.hidden {
    top: -60px;
}

.navbar a {
    color: #FFFFFF;
    text-decoration: none;
    font-size: 16px;
    padding: 10px 20px;
    transition: background 0.3s ease;
    border-radius: 5px;
}

.navbar a:hover {
    background: linear-gradient(45deg, #FF7F50, #FF6347); /* 按钮渐变 */
}

/* 章节导航系统 */
.chapter-nav {
    position: fixed;
    top: 60px;
    left: 20px;
    display: flex;
    flex-direction: column;
}

.chapter-nav a {
    color: #FFD700;
    text-decoration: none;
    margin: 5px 0;
    font-size: 14px;
    transition: color 0.3s ease;
}

.chapter-nav a:hover {
    color: #FF4500;
}

/* 主内容区样式 */
.container {
    display: grid;
    grid-template-areas:
        "header"
        "main"
        "footer";
    grid-gap: 20px;
    padding: 100px 20px 20px 20px; /* 留出导航栏空间 */
}

header {
    grid-area: header;
    background: rgba(255, 255, 255, 0.1);
    padding: 20px;
    border-radius: 10px;
}

main {
    grid-area: main;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    grid-gap: 20px;
}

footer {
    grid-area: footer;
    background: rgba(255, 255, 255, 0.1);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
}

/* 卡片样式 */
.card {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-10px);
    box-shadow: 0 6px 8px rgba(0,0,0,0.2);
}

/* 图片样式 */
.card img {
    width: 100%;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
    transition: transform 0.3s ease;
}

.card img:hover {
    transform: scale(1.05);
}

/* 按钮样式 */
.button-primary {
    background: linear-gradient(45deg, #FF7F50, #FF6347);
    border: none;
    padding: 10px 20px;
    color: #FFFFFF;
    cursor: pointer;
    border-radius: 5px;
    transition: background 0.3s ease;
}

.button-primary:hover {
    background: linear-gradient(45deg, #FF6347, #FF4500);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
    }
    
    .chapter-nav {
        flex-direction: row;
        top: auto;
        bottom: 20px;
    }
    
    .container {
        grid-template-areas:
            "header"
            "main"
            "footer";
        padding: 80px 10px 10px 10px;
    }
}