22.纯 CSS 创作出美丽的彩虹条纹文字

原文地址：https://segmentfault.com/a/1190000014858628

感想：利用四个span的::before 和 ::after创出多个WEB，给其颜色，绝对定位，再利用z-index: n；突出显示的优先级。

HTML代码：

<html>
    <head>
        <link rel="stylesheet" href="index.css">
    </head>
    <body>
        <p class="rainbow">
            web
            <span data-text="web"></span>
            <span data-text="web"></span>
            <span data-text="web"></span>
            <span data-text="web"></span>
        </p>
    </body>
</html>

CSS代码：

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background: black;
}
.rainbow {
    color: white;
    font-size: 300px;
    text-transform: uppercase;
    font-family: sans-serif;
    font-weight: bold;
    line-height: 1em;
    position: relative;
}
/* 用伪元素增加图层，形成彩虹效果 */
.rainbow span::before,
.rainbow span::after {
    content: attr(data-text);
    position: absolute;
    top: 0;
    left: 0;
    overflow: hidden;
}
.rainbow span:nth-child(1)::before {
    color: orchid;
    z-index: 1;
    height: calc(100% - 10% * 1);
}
.rainbow span:nth-child(1)::after {
    color: mediumpurple;
    z-index: 2;
    height: calc(100% - 10% * 2);
}
.rainbow span:nth-child(2)::before {
    color: deepskyblue;
    z-index: 3;
    height: calc(100% - 10% * 3);
}
.rainbow span:nth-child(2)::after {
    color: cyan;
    z-index: 4;
    height: calc(100% - 10% * 4);
}
.rainbow span:nth-child(3)::before {
    color: mediumspringgreen;
    z-index: 5;
    height: calc(100% - 10% * 5);
}
.rainbow span:nth-child(3)::after {
    color: yellow;
    z-index: 6;
    height: calc(100% - 10% * 6);
}
.rainbow span:nth-child(4)::before {
    color: gold;
    z-index: 7;
    height: calc(100% - 10% * 7);
}
.rainbow span:nth-child(4)::after {
    color: tomato;
    z-index: 8;
    height: calc(100% - 10% * 8);
}
/* 增加动画效果 */
.rainbow span::before,
.rainbow span::after {
    animation: animate 0.8s infinite alternate;
    filter: opacity(0);
}
@keyframes animate {
    from {
        filter: opacity(0);
    }

    to {
        filter: opacity(1);
    }
}
/* 为图层设置延时，增强动感 */
.rainbow span:nth-child(1)::before {
    animation-delay: calc(0.8s - 0.1s * 1);
}
.rainbow span:nth-child(1)::after {
    animation-delay: calc(0.8s - 0.1s * 2);
}
.rainbow span:nth-child(2)::before {
    animation-delay: calc(0.8s - 0.1s * 3);
}
.rainbow span:nth-child(2)::after {
    animation-delay: calc(0.8s - 0.1s * 4);
}
.rainbow span:nth-child(3)::before {
    animation-delay: calc(0.8s - 0.1s * 5);
}
.rainbow span:nth-child(3)::after {
    animation-delay: calc(0.8s - 0.1s * 6);
}
.rainbow span:nth-child(4)::before {
    animation-delay: calc(0.8s - 0.1s * 7);
}
.rainbow span:nth-child(4)::after {
    animation-delay: calc(0.8s - 0.1s * 8);
}
/* 最后，把原始文本设置为透明色 */
.rainbow {
    color: transparent;
}