巧用 CSS 动画实现动态气泡背景

试着写了一个带气泡背景的登录页面，效果如下：

首先我们先定义 10 个 li 列表标签，我用的是 Vue 框架： HTML 代码

<div>
  <ul class="bg-bubbles">
    <li v-for="i in 10" :key="i"></li>
  </ul>
</div>
<script src="https://unpkg.com/vue@next/dist/vue.js"></script>

对应的 CSS 代码

body {
  margin: 0;
  padding: 0;
}

#app {
  background: linear-gradient(to bottom right, #50A3A2, #53E3A6);
  position: absolute;
  height: 100%;
  width: 100%;
}

.bg-bubbles {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.bg-bubbles li {
  position: absolute;
  bottom: -160px;
  width: 40px;
  height: 40px;
  background-color: rgba(255, 255, 255, 0.15);
  list-style: none;
  animation: square 15s infinite;
  transition-timing-function: linear;
  border-radius: 10px;
}

.bg-bubbles li:nth-child(1) {
  left: 10%;
}

.bg-bubbles li:nth-child(2) {
  left: 20%;
  width: 90px;
  height: 90px;
  animation-delay: 2s;
  animation-duration: 7s;
}

.bg-bubbles li:nth-child(3) {
  left: 25%;
  animation-delay: 4s;
}

.bg-bubbles li:nth-child(4) {
  left: 40%;
  width: 60px;
  height: 60px;
  animation-duration: 8s;
  background-color: rgba(255, 255, 255, 0.3);
}

.bg-bubbles li:nth-child(5) {
  left: 70%;
}

.bg-bubbles li:nth-child(6) {
  left: 80%;
  width: 120px;
  height: 120px;
  animation-delay: 3s;
  background-color: rgba(255, 255, 255, 0.2);
}

.bg-bubbles li:nth-child(7) {
  left: 32%;
  width: 160px;
  height: 160px;
  animation-delay: 2s;
}

.bg-bubbles li:nth-child(8) {
  left: 55%;
  width: 20px;
  height: 20px;
  animation-delay: 4s;
  animation-duration: 15s;
}

.bg-bubbles li:nth-child(9) {
  left: 25%;
  width: 10px;
  height: 10px;
  animation-delay: 2s;
  animation-duration: 12s;
  background-color: rgba(255, 255, 255, 0.3);
}

.bg-bubbles li:nth-child(10) {
  left: 85%;
  width: 160px;
  height: 160px;
  animation-delay: 5s;
}

@keyframes square {
  0% {
    opacity: 0.5;
    transform: translateY(0px) rotate(45deg);
  }

  25% {
    opacity: 0.75;
    transform: translateY(-400px) rotate(90deg);
  }

  50% {
    opacity: 1;
    transform: translateY(-600px) rotate(135deg);
  }

  100% {
    opacity: 0;
    transform: translateY(-1000px) rotate(180deg);
  }
}

至此，一个气泡背景图就完成了。回过头来看，确实不难，但也愈来愈让人感受到 CSS 动画的魅力和强大。