/* 通用样式 */

{
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    color: #333;
    padding-bottom: 80px;
    font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
    background-image: linear-gradient(rgba(255, 255, 255, 0.2), rgba(255, 255, 255, 0.5)), url("http://img.xjh.me/random_img.php?type=bg&ctyp&return=302");
    background-size: cover;
    background-color: transparent;
    transition: opacity 0.3s ease-in-out; /* 添加过渡动画 */
}

.content {
    /* 删除上划动画 */
}

.beat-btn {
    background: linear-gradient(to bottom right, #ffb6c1, #87ceeb);
    color: #fff;
    border-radius: 50%;
    padding: 40px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, .5);
    transition: all .3s ease-in-out;
}

    .beat-btn:hover {
        transform: scale(1.1);
        box-shadow: 0 4px 8px rgba(0, 0, 0, .5);
    }

header {
    background-color: #f8f8f8;
    padding: 20px;
    text-align: center;
    border-bottom: 1px solid #ddd;
}

footer {
    height: 80px;
    width: 100%;
    background-color: #f8f8f8;
    position: fixed;
    bottom: 0;
    left: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    justify-content: space-between;
}

nav li {
    margin: 0 30px 0 0;
    font-weight: bold;
    text-transform: uppercase;
}

    nav li:last-child {
        margin-right: 0;
    }

section.content {
    padding: 50px;
    text-align: center;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: normal;
}

a:hover {
    text-decoration: underline;
}


button {
    cursor: pointer;
    background-color: #0077cc;
    color: white;
    border-radius: 4px;
    border: 0;
    padding: 8px 16px;
    font-size: 16px;
}

    button:hover {
        opacity: 0.9;
    }

img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 0 auto;
}

table {
    border-collapse: collapse;
    width: 100%;
}

th, td {
    padding: 8px;
    text-align: left;
    border-bottom: 1px solid #ddd;
}

th {
    background-color: #f2f2f2;
    font-weight: normal;
}

/* 响应式布局 */

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
    }

    nav li {
        margin-bottom: 10px;
    }
}

iframe {
			width: 100%;
			height: 100%;
			border: none;
		}

/* 动画效果 */

a[href]:not([class]) {
    color: #333;
    position: relative;
    text-decoration: none;
    padding-bottom: 3px;
}

    a[href]:not([class]):before {
        content: "";
        height: 2px;
        width: 0%;
        bottom: 0;
        position: absolute;
        background: #333;
	    
        transition: width 0.25s ease-in-out;
    }

    a[href]:not([class]):hover:before,
    a[href]:not([class]):focus:before {
        width: 100%;
    }