主要思路：通过鼠标悬浮控制每一个半边的宽度变化

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>split landing page</title>
  <link rel="stylesheet" href="./style.css">
</head>
<body>
  <div class="container">
    <div class="split left">
      <h1>Page Left</h1>
      <a href="#" class="btn">qaq</a>
    </div>
    <div class="split right">
      <h1>Page Right</h1>
      <a href="#" class="btn">qaq</a>
    </div>
  </div>
  
  <script src="./script.js"></script>
</body>
</html>

:root {
  --left-bg-color: rgba(105, 104, 179, 0.7);
  --right-bg-color: rgba(43, 43, 43, 0.8);
  --left-btn-hover-color: rgba(87, 84, 236, 1);
  --right-btn-hover-color: rgb(36, 41, 36);
  --hover-width: 75%;
  --other-width: 25%;
  --speed: 1000ms;
}

*{
  box-sizing: border-box;
}

body{
  height: 100vh;
  margin: 0;
}

h1{
  position: absolute;
  top: 20%;
  left: 50%;
  transform: translateX(-50%);
  font-size: 4rem;
  color: #fff;
  white-space: nowrap;
}

.container{
  position: relative;
  width: 100%;
  height: 100%;
}

.split{
  position: absolute;
  width: 50%;
  height: 100%;
}

.left{
  left: 0;
  background: url('../public/images/1.webp') no-repeat center center/cover;
}

.right{
  right: 0;
  background: url('../public/images/4.webp') no-repeat center center/cover;
}

.btn{
  position: absolute;
  top: 40%;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  justify-content: center;
  align-items: center;
  text-decoration: none;
  color: #fff;
  font-size: 1rem;
  font-weight: bold;
  border: 0.2rem solid #fff;
  width: 14rem;
  padding: 1.5rem;
  text-transform: uppercase;
}

.left .btn:hover{
  border-color: var(--left-btn-hover-color);
  background-color: var(--left-btn-hover-color);
}

.right .btn:hover{
  border-color: var(--right-btn-hover-color);
  background-color: var(--right-btn-hover-color);
}

.left::before{
  position: absolute;
  content: "";
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--left-bg-color);
}

.right::before{
  position: absolute;
  content: "";
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: var(--right-bg-color);
}

.hover-left .left{
  width: var(--hover-width);
}
.hover-left .right{
  width: var(--other-width);
}

.hover-right .left{
  width: var(--other-width);
}
.hover-right .right{
  width: var(--hover-width);
}

.right,
.left,
.right::before,
.left::before{
  transition: all var(--speed) ease-in-out;
}

const container = document.querySelector('.container')
const left = document.querySelector('.left')
const right = document.querySelector('.right')

left.addEventListener('mouseenter', () => {container.classList.add('hover-left')})
left.addEventListener('mouseleave', () => {container.classList.remove('hover-left')})

right.addEventListener('mouseenter', () => {container.classList.add('hover-right')})
right.addEventListener('mouseleave', () => {container.classList.remove('hover-right')})

效果如下
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Q.E.D.

一个二次元web开发咸鱼