/* 全局样式设置 */
body {
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif; /* 使用无衬线字体，保证可读性 */
    background: linear-gradient(135deg, #1E3A8A 70%, #3B82F6 30%); /* 主色调渐变背景 */
    color: #6B7280; /* 中性色字体颜色 */
    line-height: 1.6;
}

/* 响应式布局 */
.container {
    display: grid;
    grid-template-columns: repeat(12, 1fr); /* 12列网格系统 */
    gap: 20px;
    padding: 20px;
    max-width: 1920px;
    margin: 0 auto;
}

/* 响应式调整 */
@media (max-width: 1200px) {
    .container {
        grid-template-columns: repeat(8, 1fr);
    }
}

@media (max-width: 768px) {
    .container {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 480px) {
    .container {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* 顶部导航栏样式 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(30, 58, 138, 0.9); /* 半透明背景 */
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 30px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); /* 阴影效果 */
    z-index: 1000;
}

.navbar .logo {
    color: #FFFFFF;
    font-size: 1.5rem;
    font-weight: bold;
}

.navbar .nav-links a {
    color: #FFFFFF;
    text-decoration: none;
    margin-left: 20px;
    font-size: 1rem;
    transition: color 0.3s ease;
}

.navbar .nav-links a:hover {
    color: #F97316; /* 点缀色悬停效果 */
}

/* 主要内容区域 */
.main-content {
    padding-top: 100px; /* 为固定导航栏留出空间 */
    grid-column: 1 / -1;
    display: flex;
    flex-direction: column;
    gap: 40px;
}

/* 卡片式设计 */
.card {
    background-color: #FFFFFF;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    cursor: pointer;
}

.card:hover {
    transform: translateY(-10px); /* 悬停提升效果 */
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.2);
}

.card img {
    width: 100%;
    max-width: 650px;
    height: auto;
    display: block;
}

.card-content {
    padding: 20px;
}

.card-content h3 {
    font-size: 1.5rem;
    color: #1E3A8A;
    margin-bottom: 10px;
}

.card-content p {
    font-size: 1rem;
    color: #6B7280;
}

/* 图片样式 */
.decorative-image {
    border-radius: 15px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.decorative-image:hover {
    transform: scale(1.05);
}

/* 标题样式 */
h2, h3, h4 {
    color: #1E3A8A;
    margin-bottom: 15px;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.75rem;
}

h4 {
    font-size: 1.5rem;
}

/* 文本内容样式 */
p {
    font-size: 1rem;
    color: #6B7280;
    margin-bottom: 15px;
}

/* 链接样式 */
a {
    color: #3B82F6;
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: #F97316;
}

/* 强调文字 */
strong {
    color: #1E3A8A;
}

/* 代码块样式 */
pre {
    background: #F3F4F6;
    padding: 15px;
    border-radius: 8px;
    overflow-x: auto;
    margin-bottom: 20px;
}

code {
    font-family: 'Courier New', Courier, monospace;
    color: #3B82F6;
}

/* 交互动效 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out forwards;
}

/* 提示样式 */
.reference-note {
    background-color: #10B981;
    color: #FFFFFF;
    padding: 10px;
    border-radius: 5px;
    text-align: center;
    font-size: 1.2rem;
    margin-bottom: 30px;
}

/* 折叠区域样式 */
.collapsible {
    background-color: #F3F4F6;
    color: #1E3A8A;
    cursor: pointer;
    padding: 10px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 1rem;
    transition: background-color 0.3s ease;
    border-radius: 5px;
}

.collapsible:hover {
    background-color: #E5E7EB;
}

.collapsible:after {
    content: '\002B'; /* 加号符号 */
    float: right;
}

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

.content {
    padding: 0 15px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
    background-color: #F9FAFB;
    border-radius: 5px;
}

.content.show {
    max-height: 500px; /* 根据内容长度调整 */
}

/* 点缀色按钮 */
.button {
    background-color: #F97316;
    color: #FFFFFF;
    padding: 10px 20px;
    border: none;
    border-radius: 25px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.button:hover {
    background-color: #EA580C;
}

/* 页脚样式 */
.footer {
    grid-column: 1 / -1;
    background-color: #1E3A8A;
    color: #FFFFFF;
    text-align: center;
    padding: 20px 0;
}