/* 
整体页面样式设计
使用现代Web技术栈，采用响应式设计，确保在各种设备上都能获得良好的视觉体验。
*/

/* 全局样式 */
body {
    margin: 0;
    padding: 0;
    font-family: 'Open Sans', sans-serif; /* 使用Open Sans无衬线字体 */
    color: #1E3A8A; /* 深蓝色字体 */
    background: linear-gradient(135deg, #6B46C1 70%, #FEB2B2 25%, #F6AD55 5%); /* 渐变背景，遵循黄金比例配色 */
    line-height: 1.6;
    overflow-x: hidden; /* 避免水平滚动条 */
}

/* 固定导航栏 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(30, 58, 138, 0.9); /* 半透明深蓝色 */
    padding: 20px;
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.3s ease;
}

.navbar:hover {
    background-color: rgba(30, 64, 175, 0.9); /* 深蓝色加深 */
}

.navbar ul {
    list-style: none;
    display: flex;
    gap: 30px;
    margin: 0;
    padding: 0;
}

.navbar ul li {
    position: relative;
}

.navbar ul li a {
    color: #FFFFFF;
    text-decoration: none;
    font-size: 16px;
    transition: color 0.3s ease;
}

.navbar ul li a:hover {
    color: #F6AD55; /* 点缀色 */
}

.navbar ul li ul {
    display: none;
    position: absolute;
    top: 40px;
    left: 0;
    background-color: #3B82F6; /* 辅助色 */
    padding: 10px;
    border-radius: 5px;
    list-style: none;
}

.navbar ul li:hover ul {
    display: block;
}

.navbar ul li ul li {
    margin: 5px 0;
}

.navbar ul li ul li a {
    font-size: 14px;
}

/* 主要内容区域 */
.main {
    padding-top: 100px; /* 为固定导航栏预留空间 */
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 40px;    margin-top: 60px;
}

@media (min-width: 768px) {
    .main {
        grid-template-columns: 1fr 1fr;
    }
}

@media (min-width: 1200px) {
    .main {
        grid-template-columns: 1fr 1fr 1fr;
    }
}

/* 标题样式 */
h1, h2, h3, h4 {
    color: #1E3A8A;
    text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
}

h1 {
    font-size: 2.5em;
    text-align: center;
    margin-bottom: 20px;
}

h2 {
    font-size: 2em;
    margin-bottom: 15px;
}

h3 {
    font-size: 1.75em;
    margin-bottom: 10px;
}

h4 {
    font-size: 1.5em;
    margin-bottom: 10px;
}

/* 段落样式 */
p {
    font-size: 16px;
    line-height: 1.8;
    margin-bottom: 20px;
    color: #2D3748;
}

/* 图片样式 */
img.decorative {
    width: 100%;
    max-width: 320px;
    border-radius: 15px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

img.decorative:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 10px rgba(0,0,0,0.15);
}

/* 代码块样式 */
pre {
    background: #F3F4F6;
    padding: 20px;
    border-radius: 10px;
    overflow: visible;
    position: relative;
}

pre code {
    font-family: 'Courier New', Courier, monospace;
    color: #2D3748;
    font-size: 15px;
}

pre code::before {
    content: "CSS3 示例代码";
    position: absolute;
    top: -20px;
    left: 10px;
    background: #1E3A8A;
    color: #FFFFFF;
    padding: 5px 10px;
    border-radius: 5px;
    font-size: 12px;
}

pre code {
    overflow: visible; /* 防止::before被遮挡 */
}

/* 按钮样式 */
.button {
    background: linear-gradient(135deg, #6B46C1, #F6AD55);
    color: #FFFFFF;
    padding: 15px 30px;
    border: none;
    border-radius: 25px;
    font-size: 16px;
    cursor: pointer;
    transition: transform 0.3s ease, background 0.3s ease;
}

.button:hover {
    transform: scale(1.05);
    background: linear-gradient(135deg, #553C9A, #D69E2E);
}

/* 提示信息样式 */
.notice {
    background-color: rgba(255, 255, 255, 0.8);
    padding: 20px;
    border-left: 5px solid #F6AD55;
    margin-bottom: 40px;
    border-radius: 5px;
    font-size: 16px;
    color: #1A202C;
}

/* 折叠区域样式 */
.collapsible {
    background-color: #E2E8F0;
    color: #1A202C;
    cursor: pointer;
    padding: 10px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 16px;
    border-radius: 5px;
    transition: background-color 0.3s ease;
}

.collapsible:hover {
    background-color: #CBD5E0;
}

.collapsible:after {
    content: '\002B'; /* 加号 */
    float: right;
    margin-left: 5px;
}

.collapsible.active:after {
    content: "\2212"; /* 减号 */
}

.content {
    padding: 0 18px;
    display: none;
    overflow: hidden;
    background-color: #F7FAFC;
    border-radius: 5px;
}

.content p {
    margin: 15px 0;
}

/* 加载动画 */
.loader {
    border: 8px solid #F3F4F6;
    border-top: 8px solid #3B82F6;
    border-radius: 50%;
    width: 60px;
    height: 60px;
    animation: spin 1s linear infinite;
    margin: 100px auto;
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* 滚动动画 */
.section-container {
    display: flex;
    flex-direction: column;
    scroll-snap-type: y mandatory;
    height: 100%;
    overflow-y: scroll;
}

.section {
    scroll-snap-align: start;
    flex: none;
    min-height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 40px;
    background-color: #FFFFFF;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    border-radius: 10px;
    margin: 20px;
}

.section:nth-child(even) {
    background-color: #F3F4F6;
}

/* 响应式设计 */
@media (max-width: 767px) {
    .navbar ul {
        flex-direction: column;
        background-color: rgba(30, 58, 138, 0.95);
        position: absolute;
        top: 60px;
        left: -100%;
        width: 100%;
        transition: left 0.3s ease;
    }

    .navbar ul.show {
        left: 0;
    }

    .navbar .menu-toggle {
        display: block;
        cursor: pointer;
        color: #FFFFFF;
        font-size: 24px;
    }

    .main {
        grid-template-columns: 1fr;
    }
}

@media (min-width: 768px) {
    .navbar .menu-toggle {
        display: none;
    }
}