/* ===== CSS Reset & Base ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: #337ab7;
    transition: color 0.3s;
}

a:hover {
    color: #23527c;
}

img {
    max-width: 100%;
    height: auto;
}

/* ===== Container ===== */
.container {
    max-width: 1170px;
    margin: 0 auto;
    padding: 0 15px;
}

/* ===== Header / Banner ===== */
.header-banner {
    background-color: #c9eefe;
}

.header-banner img {
    display: block;
    margin: 0 auto;
    width: 100%;
    max-width: 1170px;
}

/* ===== Navigation (Responsive) ===== */
.nav-wrapper {
    position: relative;
    z-index: 1000;
}

/* 导航蓝色背景条宽度与横幅图片对齐（1170px） */
.nav-container {
    max-width: 1170px;
    margin: 0 auto;
    background-color: #337ab7;
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: #fff;
    font-size: 28px;
    padding: 12px 15px;
    cursor: pointer;
    outline: none;
}

.nav-list {
    list-style: none;
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
}

.nav-list li {
    position: relative;
}

.nav-list li a {
    display: block;
    padding: 14px 24px;
    color: #fff;
    font-size: 15px;
    font-weight: 500;
    white-space: nowrap;
    transition: background-color 0.3s, color 0.3s;
    border-bottom: 3px solid transparent;
}

.nav-list li a:hover,
.nav-list li a.active {
    background-color: rgba(255, 255, 255, 0.15);
    border-bottom-color: #ffd700;
    color: #ffd700;
}

/* ===== Main Layout ===== */
.main-section {
    padding: 2em 0;
}

.main-grid {
    display: flex;
    gap: 30px;
}

.main-content {
    flex: 1;
    min-width: 0;
    background: #fff;
    padding: 30px 25px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.sidebar {
    width: 260px;
    flex-shrink: 0;
    background: #fff;
    padding: 20px 15px;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

/* ===== Article Content ===== */
.article-title {
    text-align: center;
    font-size: 22px;
    font-weight: 700;
    color: #222;
    margin-bottom: 20px;
    line-height: 1.4;
}

.article-body {
    font-size: 15px;
    color: #444;
}

.article-body p {
    margin-bottom: 15px;
    text-indent: 2em;
}

.article-body strong {
    color: #222;
}

.article-body ol {
    margin: 10px 0 15px 2em;
    padding-left: 1em;
}

.article-body ol li {
    margin-bottom: 6px;
    text-indent: 0;
}

/* ===== Sidebar ===== */
.sidebar-title {
    font-weight: 700;
    font-size: 16px;
    color: #337ab7;
    text-align: center;
    padding-bottom: 10px;
    margin-bottom: 15px;
    border-bottom: 2px solid #337ab7;
}

.sidebar-images {
    text-align: center;
}

.sidebar-images figure {
    margin-bottom: 15px;
}

.sidebar-images figure img {
    border: 1px solid #ddd;
    border-radius: 4px;
    transition: opacity 0.3s;
}

.sidebar-images figure img:hover {
    opacity: 0.8;
}

.sidebar-links {
    margin-top: 20px;
    padding-top: 15px;
    border-top: 1px solid #eee;
}

.sidebar-links ul {
    list-style: none;
}

.sidebar-links ul li {
    padding: 6px 0;
    border-bottom: 1px dashed #eee;
}

.sidebar-links ul li:last-child {
    border-bottom: none;
}

.sidebar-links ul li a {
    font-size: 14px;
    display: block;
    padding: 2px 0;
}

.sidebar-links ul li a::before {
    content: "▸ ";
    color: #337ab7;
}

/* ===== Footer ===== */
.footer {
    background-color: #337ab7;
    color: #a5a5a5;
    padding: 18px 40px;
    line-height: 1.8;
    font-size: 14px;
    text-align: center;
}

/* ========================================================= */
/*  Responsive – Tablet & Mobile                              */
/* ========================================================= */

/* 平板 (< 992px) */
@media (max-width: 992px) {
    .sidebar {
        width: 220px;
    }
}

/* 手机 (< 768px) */
@media (max-width: 768px) {
    /* ---- 导航切换 ---- */
    .nav-toggle {
        display: block;
        width: 100%;
        text-align: left;
    }

    .nav-toggle::after {
        content: " ☰ 导航菜单";
        font-size: 16px;
    }

    .nav-toggle.active::after {
        content: " ✕ 关闭菜单";
    }

    .nav-list {
        display: none;
        flex-direction: column;
        width: 100%;
        background-color: #286090;
    }

    .nav-list.open {
        display: flex;
    }

    .nav-list li {
        width: 100%;
        border-top: 1px solid rgba(255, 255, 255, 0.15);
    }

    .nav-list li a {
        padding: 12px 20px;
        text-align: left;
        border-bottom: none;
        white-space: normal;
    }

    .nav-list li a:hover,
    .nav-list li a.active {
        border-bottom-color: transparent;
        background-color: rgba(0, 0, 0, 0.15);
    }

    /* ---- 主布局变为单列 ---- */
    .main-grid {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
    }

    .sidebar-images {
        display: flex;
        flex-wrap: wrap;
        gap: 10px;
        justify-content: center;
    }

    .sidebar-images figure {
        flex: 0 0 auto;
        margin-bottom: 0;
    }

    .sidebar-images figure img {
        width: 140px;
        height: auto;
    }

    .article-title {
        font-size: 18px;
    }
}

/* 小手机 (< 480px) */
@media (max-width: 480px) {
    .nav-list li a {
        font-size: 14px;
        padding: 10px 15px;
    }

    .article-body {
        font-size: 14px;
    }

    .sidebar-images figure img {
        width: 110px;
    }

    .footer {
        padding: 12px 15px;
        font-size: 12px;
    }
}