<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
input {
outline: none;
/*过渡效果*/
transition: all 1s;
}
input:focus {
font-weight:bold;">pink;
border: 1px solid red;
height: 30px;
}
</style>
</head>
<body>
<input type="text" name="" id="">
</body>
</html>
原文：https://www.cnblogs.com/ericblog1992/p/12924852.html