/* 全局样式设置 */
body {
    margin: 0;
    padding: 0;
    font-family: 'Roboto', sans-serif; /* 使用现代感强的无衬线字体 */
    background: linear-gradient(135deg, #0d1b2a, #1b263b, #415a77); /* 主色调渐变背景 */
    color: #ffffff;
    line-height: 1.6;
    overflow-x: hidden; /* 防止出现横向滚动条 */
}

/* 导航栏样式 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(13, 27, 42, 0.9); /* 半透明深色背景 */
    padding: 20px;
    display: flex;
    justify-content: space-around;
    align-items: center;
    z-index: 1000;
    transition: background 0.3s ease;
}

.navbar a {
    color: #ffffff;
    text-decoration: none;
    margin: 0 15px;
    font-size: 1.1em;
    transition: color 0.3s ease;
}

.navbar a:hover {
    color: #2ec4b6; /* 点缀色悬停效果 */
}

/* 首屏样式 */
.header {
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    background: url('https://images.gptkong.com/demo/sample1.png') no-repeat center center/cover;
    position: relative;
}

.header::after {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(13, 27, 42, 0.6); /* 半透明覆盖层 */
}

.header-content {
    position: relative;
    z-index: 1;
}

.header-content h1 {
    font-size: 3em;
    margin-bottom: 20px;
    animation: fadeInDown 2s ease-out;
}

.header-content p {
    font-size: 1.5em;
    max-width: 800px;
    margin: 0 auto 40px;
    animation: fadeInUp 2s ease-out;
}

.cta-button {
    background: #2ec4b6;
    border: none;
    padding: 15px 30px;
    color: #ffffff;
    font-size: 1.2em;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s ease, transform 0.3s ease;
}

.cta-button:hover {
    background: #ff9f1c;
    transform: scale(1.05);
}

/* 模块化布局样式 */
.section {
    padding: 100px 20px;
    position: relative;
}

.section:nth-child(even) {
    background: rgba(27, 38, 59, 0.8); /* 辅助色背景 */
}

.section-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
    gap: 40px;
    align-items: center;
}

.section-content img {
    width: 320px;
    height: 320px;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.5);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.section-content img:hover {
    transform: scale(1.05);
    box-shadow: 0 15px 25px rgba(0, 0, 0, 0.7);
}

.section-text {
    flex: 1;
    min-width: 300px;
}

.section-text h2 {
    font-size: 2em;
    margin-bottom: 20px;
    position: relative;
    padding-bottom: 10px;
}

.section-text h2::after {
    content: "";
    width: 50px;
    height: 3px;
    background: #2ec4b6;
    position: absolute;
    bottom: 0;
    left: 0;
}

.section-text p {
    font-size: 1.1em;
    margin-bottom: 15px;
}

.code-example {
    background: #0d1b2a;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 20px 0;
}

.code-example code {
    color: #2ec4b6;
    font-family: 'Courier New', Courier, monospace;
    font-size: 1em;
}

/* 表格样式 */
.table-container {
    overflow-x: auto;
}

.table-container table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
}

.table-container thead {
    background: #1b263b;
}

.table-container th, .table-container td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #415a77;
}

.table-container th {
    color: #ffffff;
}

.table-container td {
    color: #ffffff;
}

/* 动画定义 */
@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 回到顶部按钮样式 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: #2ec4b6;
    color: #ffffff;
    padding: 10px 15px;
    border-radius: 50%;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s;
    cursor: pointer;
    z-index: 1000;
}

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

/* 折叠区域样式 */
.collapsible {
    background: rgba(27, 38, 59, 0.8);
    color: #ffffff;
    cursor: pointer;
    padding: 18px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 1.2em;
    transition: background 0.3s ease;
    border-radius: 5px;
}

.collapsible:hover {
    background: #2ec4b6;
}

.collapsible:after {
    content: '\002B'; /* 加号符号 */
    font-size: 1.2em;
    float: right;
}

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

.content {
    padding: 0 18px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    background: rgba(13, 27, 42, 0.8);
    border-radius: 0 0 5px 5px;
    margin-bottom: 10px;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
    }

    .section-content {
        flex-direction: column;
    }

    .header-content h1 {
        font-size: 2.5em;
    }

    .header-content p {
        font-size: 1.2em;
    }

    .cta-button {
        font-size: 1em;
        padding: 10px 20px;
    }
}