/* 全局样式设置 */
/* 设置主色调、辅助色和点缀色 */
:root {
    --main-color: #2C3E50; /* 深蓝色 */
    --secondary-color: #ECF0F1; /* 浅灰色 */
    --accent-color: #E67E22; /* 橙色 */
    --background-color: #34495E; /* 墨绿色 */
    --font-family: 'Roboto', sans-serif;
    --base-font-size: 16px;
}

/* 全局字体和背景 */
body {
    margin: 0;
    padding: 0;
    font-family: var(--font-family);
    font-size: var(--base-font-size);
    background: linear-gradient(135deg, var(--background-color), var(--main-color));
    color: var(--secondary-color);
    overflow-x: hidden;
}

/* 样式重置 */
* {
    box-sizing: border-box;
}

/* 导航栏样式 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(44, 62, 80, 0.8); /* 半透明背景 */
    backdrop-filter: blur(10px); /* 磨砂玻璃效果 */
    padding: 20px 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    transition: background 0.3s ease;
}

.navbar.scrolled {
    background: rgba(44, 62, 80, 1);
}

.navbar a {
    color: var(--secondary-color);
    text-decoration: none;
    margin: 0 15px;
    font-size: 16px;
    transition: color 0.3s;
}

.navbar a:hover {
    color: var(--accent-color);
}

/* 汉堡菜单样式（移动端） */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.hamburger div {
    width: 25px;
    height: 3px;
    background-color: var(--secondary-color);
    margin: 4px 0;
    transition: all 0.3s ease;
}

/* 章节导航系统 */
.chapter-nav {
    position: fixed;
    top: 80px;
    right: 20px;
    background: rgba(44, 62, 80, 0.7);
    backdrop-filter: blur(5px);
    padding: 15px;
    border-radius: 10px;
    z-index: 999;
}

.chapter-nav a {
    display: block;
    color: var(--secondary-color);
    text-decoration: none;
    margin: 10px 0;
    font-size: 14px;
    transition: color 0.3s;
}

.chapter-nav a:hover {
    color: var(--accent-color);
}

/* 主要内容区块 */
.section {
    padding: 100px 50px;
    min-height: 100vh;
}

.section:nth-child(even) {
    background: rgba(44, 62, 80, 0.6);
}

.section:nth-child(odd) {
    background: rgba(52, 73, 94, 0.6);
}

.section h2, .section h3, .section h4 {
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.section p {
    line-height: 1.6;
    margin-bottom: 20px;
}

/* 图文并茂的布局 */
.content-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    align-items: start;
}

.content-grid img {
    width: 100%;
    border-radius: 15px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.3);
    transition: transform 0.3s, box-shadow 0.3s;
}

.content-grid img:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 25px rgba(0,0,0,0.5);
}

/* 代码块样式 */
pre {
    background: rgba(52, 73, 94, 0.8);
    padding: 15px;
    border-radius: 10px;
    overflow-x: auto;
    box-shadow: 0 4px 15px rgba(0,0,0,0.3);
}

code {
    color: #ecf0f1;
    font-family: 'Courier New', Courier, monospace;
    font-size: 14px;
}

/* 按钮样式 */
.button {
    background-color: var(--accent-color);
    color: #fff;
    padding: 12px 25px;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    cursor: pointer;
    transition: background-color 0.3s, transform 0.3s;
}

.button:hover {
    background-color: #d35400;
    transform: scale(1.05);
}

/* 卡片式设计 */
.card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 12px;
    padding: 20px;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

/* 动态翻转卡片 */
.flip-card {
    background-color: transparent;
    perspective: 1000px;
}

.flip-card-inner {
    position: relative;
    width: 100%;
    height: 100%;
    text-align: center;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

.flip-card:hover .flip-card-inner {
    transform: rotateY(180deg);
}

.flip-card-front, .flip-card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 10px;
}

.flip-card-front {
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(5px);
}

.flip-card-back {
    background: rgba(44, 62, 80, 0.9);
    color: #fff;
    transform: rotateY(180deg);
}

/* 动画效果 */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.fade-in {
    animation: fadeIn 1s ease-in-out;
}

@keyframes slideIn {
    from { transform: translateX(-100%); }
    to { transform: translateX(0); }
}

.slide-in {
    animation: slideIn 0.5s ease-out;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar {
        padding: 15px 20px;
    }
    .navbar a {
        margin: 0 10px;
        font-size: 14px;
    }
    .hamburger {
        display: flex;
    }
    .chapter-nav {
        display: none;
    }
    .content-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .section {
        padding: 80px 20px;
    }
    .navbar a {
        display: none;
    }
}

/* 美化章节导航的可点击效果 */
.chapter-nav a::before {
    content: "• ";
    color: var(--accent-color);
}