/* -------------for black mode----------- */
.dark {
    background-color: #121212;
    /* 暗背景颜色 */
    font-family: Impact, Haettenschweiler, 'Arial Narrow Bold', sans-serif;
}

.dark #history {
    background-color: rgba(255, 255, 255, 0.8);
    color: black;
    width: 100%;
    height: 500px;
}

body {
    transition: background-color 0.3s ease;
}

.dark a {
    color: #330e5e;
    /* 链接颜色 */
}

/* -------------dark heading------------ */
.dark h2 {
    color: pink;
    font-weight: bold;
    font-size: 30px;
}

.dark h4 {
    color: rgb(255, 78, 161);
    font-size: 16px;
}

.dark h1 {
    color: pink;
    font-weight: bold;
    font-size: 70px;
    font-family: Impact, Haettenschweiler, 'Arial Narrow Bold', sans-serif;
}

/* --------------dark menu---------------*/
.dark #index-nav {
    overflow: hidden;
    background-color: lightpink;
}

.dark #index-nav a {
    float: left;
    display: block;
    color: #000000;
    text-align: center;
    padding: 12px 12px;
    text-decoration: none;
    font-size: 16px;
    font-family: "Arial Black", Gadget, sans-serif;
    ;
    border-radius: 5px;
    font-weight: bold;
}

.dark #index-nav a:hover {
    background-color: #ddd;
    color: black;
}

.dark .content {
    padding: 16px;
}



/* ----------black mode bottom------------- */
.darkButton {
    padding: 10px 20px;
    font-size: 18px;
    text-align: center;
    cursor: pointer;
    outline: none;
    color: #fff;
    background-color: #000000;
    border: none;
    border-radius: 9px;
    box-shadow: 0 9px #999;
    margin-left: 150px;

    position: fixed;
    /* 或 absolute，根据需要选择 */
    top: 20px;
    /* 顶部距离 */
    right: 20px;
    /* 右侧距离 */
    z-index: 1000;
    /* 确保按钮不会被其他元素覆盖 */
}

.darkButton:hover {
    background-color: steelblue
}

.darkButton:active {
    background-color: #3B5998;
    box-shadow: 0 5px #666;
    transform: translateY(4px);
}