有趣的 CSS - 动态圆点水波纹效果

先看效果

整体效果

这个效果使用 css 中 animation 属性，以及搭配伪元素 ::after、::before 来实现两个圆交替变化。

核心代码

html部分代码

<div>
  <label class="dot"></label>
</div>

label 标签画圆点主体。

css部分代码

.app{
  width: 100%;
  height: 100vh;
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}
.dot {
  width: 48px;
  height: 48px;
  display: block;
  position: relative;
  border-radius: 50%;
  background-color: blue;
  z-index: 1;
}
.dot::after {
  width: 100%;
  height: 100%;
  content: "";
  border-radius: 50%;
  position: absolute;
  top: 0;
  left: 0;
  z-index: -2;
  background-color: blue;
  animation: dot-play 4s linear 400ms infinite;
}
.dot::before {
  width: 100%;
  height: 100%;
  content: "";
  border-radius: 50%;
  position: absolute;
  top: 0;
  left: 0;
  z-index: -1;
  background-color: blue;
  animation: dot-play 4s linear 200ms infinite;
  animation-delay: 2s; /* 延迟 2s */
}
@keyframes dot-play{
  from{
    transform: scale(1);
    opacity: .2;
  }
  to{
    transform: scale(4);
    opacity: 0;
  }
}

伪元素基于主体圆写出两个蓝色圆形来做水波纹，并设置 animation 属性进行变化。
注意：第二个伪元素的圆形，延迟 2s 启动 animation 动画。

完整代码

html代码

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="style.css?k3f22ww">
  <title>03 圆点水波纹效果</title>
</head>
<body>
  <div class="app">
    <label class="dot"></label>
  </div>
</body>
</html>

css代码

*{
  margin: 0;
  padding: 0;
  list-style: none;
  transition: .5s;
}
html,body{
  background-color: #f5f5f5;
  color: #fff;
  font-size: 14px;
}
.app{
  width: 100%;
  height: 100vh;
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}
.dot {
  width: 48px;
  height: 48px;
  display: block;
  position: relative;
  border-radius: 50%;
  background-color: blue;
  z-index: 1;
}
.dot::after {
  width: 100%;
  height: 100%;
  content: "";
  border-radius: 50%;
  position: absolute;
  top: 0;
  left: 0;
  z-index: -2;
  background-color: blue;
  animation: dot-play 4s linear 400ms infinite;
}
.dot::before {
  width: 100%;
  height: 100%;
  content: "";
  border-radius: 50%;
  position: absolute;
  top: 0;
  left: 0;
  z-index: -1;
  background-color: blue;
  animation: dot-play 4s linear 200ms infinite;
  animation-delay: 2s; /* 延迟 2s */
}
@keyframes dot-play{
  from{
    transform: scale(1);
    opacity: .2;
  }
  to{
    transform: scale(4);
    opacity: 0;
  }
}