13.纯 CSS 创作一个冒着热气的咖啡杯

原文地址：https://segmentfault.com/a/1190000014734039

感想：伪元素::before ::after 真的很强大，动画也是。

HTML代码：

<div class="coffee">
       <div class="vapor">
              <span></span>
              <span></span>
              <span></span>
              <span></span>
              <span></span>
       </div>
       <div class="cup"></div>
       <div class="plate"></div>
</div>

CSS代码：

html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: brown;
}
.coffee {
    display: flex;
    flex-direction: column;
    align-items: center;
    height: calc(9em + 1em +2em);
    position: relative;
}

/* 画出杯子主体 */
.coffee .cup{
    position: relative;
    width: 10em;
    height: 9em;
    background-color: white;
    border-bottom-left-radius: 1.5em;
    border-bottom-right-radius: 1.5em;
}
/* 用伪元素画出杯口 */
.coffee .cup::before{
    content: '';
    position: absolute;
    width: 100%;
    height: 2em;
    background-color: chocolate;
    border: 0.5em solid white;
    box-sizing: border-box;
    border-radius: 50%;
    top: -1em;
    box-shadow: inset 0 0 1em rgba（0,0,0,0.5）;
}
/* 用伪元素画出杯子把手 */
.coffee .cup::after{
    content:'';
    position: absolute;
    width: 3em;
    height: 3.5em;
    border: 0.8em solid white;
    border-radius: 50%;
    top: 20%;
    left: 80%;
}
/* 画出托盘 */
.coffee .plate {
    width: 16em;
    height: 1em;
    background-color: white;
    border-bottom-left-radius: 50%;
    border-bottom-right-radius: 50%;
    position: absolute;
    bottom: -1px;
}
/* dom元素增加杯中冒出的热气 */
/* 冒出的热气 */
.coffee .vapor{
    width: 7em;
    display: flex;
    justify-content: space-between;
}
.coffee .vapor span{
    width: 0.1em;
    min-width: 1px;
    height: 2em;
    background-color: white;
    animation: evaporation 2s linear infinite;
    filter: opacity(0);
}
@keyframes evaporation{
    from{
        transform: translateY(0);
        filter: opacity(1) blur(0.2em);
    }
    to{
        transform: translateY(-4em);
        filter: opacity(0) blur(0.4em);
    }
}
/* 最后，调整每条热气的延迟时间，使动感更强 */
.coffee .vapor span:nth-child(1) {
    animation-delay: 0.5s;
}
.coffee .vapor span:nth-child(2) {
    animation-delay: 0.1s;
}
.coffee .vapor span:nth-child(3) {
    animation-delay: 0.3s;
}
.coffee .vapor span:nth-child(4) {
    animation-delay: 0.4s;
}
.coffee .vapor span:nth-child(5) {
    animation-delay: 0.2s;
}