24.纯 CSS 创作出平滑的层叠海浪特效

原文地址：https://segmentfault.com/a/1190000014895634

感想：这里的波浪只是侧面的，利用几个平面一部分弧旋转得到。

HTML代码：

<div class="sea">
    <p class="title">the sea</p>
    <span class="wave"></span>
    <span class="wave"></span>
    <span class="wave"></span>
</div>

CSS代码：

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background: linear-gradient(antiquewhite, navajowhite);
}
.sea {
    position: relative;
    width: 300px;
    height: 300px;
    background-color: whitesmoke;
    background-image: linear-gradient(
        darkblue,
        rgba(255, 255, 255, 0) 80%,
        rgba(255, 255, 255, 0.5));
    border-radius: 5px;
    box-shadow: 0 2px 30px rgba(0, 0, 0, 0.2);
    overflow: hidden;
}
/* 这里只有水平居中和行高一定 */
.sea .title {
    position: absolute;
    width: 100%;
    color: white;
    font-size: 24px;
    font-family: serif;
    text-align: center;
    line-height: 250px;
    text-transform: uppercase;
    letter-spacing: 0.4em;
    z-index: 1;
}
/* 制作海浪动画效果: 让三个平面按不同时间旋转 */
.sea .wave {
    position: absolute;
    top: -250px;
    left: -100px;
    width: 500px;
    height: 500px;
    background: deepskyblue;
    border-radius: 43%;
    filter: opacity(0.4);
    /* 加大海浪的波动幅度:设置旋转元素的基点位置 */
    transform-origin: 50% 48%;
    animation: drift linear infinite;
}
.sea .wave:nth-of-type(1) {
    animation-duration: 5s;
}
.sea .wave:nth-of-type(2) {
    animation-duration: 7s;
}
.sea .wave:nth-of-type(3) {
    animation-duration: 9s;
    /* 增加颜色差异 */
    background-color: orangered;
    filter: opacity(0.1);
}
@keyframes drift {
    from {
        transform: rotate(360deg);
    }
}