body {
    font-family: 'Segoe UI', Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f9f9f9;
}
header {
    background: url('../css/background.png') no-repeat center center;
    background-size: cover;
    background-position: center;
    background-attachment: local;
    color: white;
    padding: 20px;
    border-radius: 5px;
    margin-bottom: 30px;
    position: relative;
    min-height: 200px; /* 设置最小高度确保显示区域 */
    display: flex;
    flex-direction: column;
    justify-content: center;
}
header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    border-radius: 5px;
}
header h1, header p {
    position: relative;
    z-index: 1;
}
h1 {
    margin: 0;
    font-size: 2.2em;
}
.container {
    display: flex;
    gap: 30px;
    margin-top: 20px;
    transition: all 0.3s;
}

@media (max-width: 768px) {
    body {
        padding-top: 0;
    }
}
nav {
    width: 250px;
    background: white;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: sticky;
    top: 20px;
    align-self: flex-start;
    max-height: calc(100vh - 40px);
    overflow-y: auto;
}
nav ul {
    list-style: none;
    padding: 0;
}
nav li {
    margin-bottom: 10px;
}
nav a {
    text-decoration: none;
    color: #3b75af;
    display: block;
    padding: 8px 12px;
    border-radius: 4px;
}
nav a:hover {
    background-color: #f0f0f0;
}
nav ul ul {
    margin-left: 15px;
    display: block; /* 修改为直接显示 */
}
nav li {
    margin-bottom: 15px; /* 增加间距 */
}
nav > ul > li > a {
    font-weight: bold; /* 一级菜单加粗 */
    font-size: 1em; /* 一级菜单字体大小 */
    color: #2c3e50;
}
.submenu li {
    margin-bottom: 8px;
}
.submenu a {
    padding: 5px 12px;
    font-size: 0.85em; /* 二级菜单字体缩小 */
    color: #666;
    font-weight: normal; /* 二级菜单不加粗 */
}
.submenu a:hover {
    color: #2c3e50;
}
main {
    flex: 1;
    background: white;
    padding: 30px;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    html {
        scroll-behavior: smooth;
    }
}
.help-section {
    margin-bottom: 40px;
}
.help-section h2 {
    color: #2c3e50;
    border-bottom: 2px solid #eee;
    padding-bottom: 10px;
}
.help-section h3 {
    background-color: #d6d5d5; /* 浅紫色背景 */
    color: #2e2525; /* 黑色文字 */
    padding: 8px 12px;
    border-radius: 4px;
    margin-top: 20px;
}
.help-section h3 + p {
    margin-top: 10px;
    padding-left: 0px;
}
footer {
    text-align: center;
    margin-top: 30px;
    padding: 20px;
    color: #777;
    font-size: 0.9em;
}
nav a:target {
    color: #e74c3c;
    transition: color 0.3s ease;
}
:target h2, :target h3 {
    color: #e74c3c;
}

/* 图片放大全屏样式 */
.img-modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.9);
    text-align: center;
}

.img-modal img {
    max-width: 90%;
    max-height: 90%;
    margin: auto;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
}

.close-btn {
    position: absolute;
    top: 15px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    cursor: pointer;
}


/* 特别提示样式 */
.important-note {
    display: inline-block;
    background: #fbf6ae;
    color: #311e1e;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 10px 0;
    font-weight: bold;
    border-left: 4px solid rgb(247, 8, 8);
    position: relative;
    overflow: hidden;
}

.important-note::before {
    content: "";
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent 33%, rgba(255,255,255,0.1) 50%, transparent 66%);
    animation: shine 3s infinite linear;
}

@keyframes shine {
    100% {
        transform: translateX(100%);
    }
}