<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>0.5px边框实现</title>
<style>
.btn {
position: relative;
width: 100px;
-webkit-border-radius: 5px;
border-radius: 5px;
text-align: center;
line-height: 42px;
background-color: #ededed;
}
.btn::after {
content: "";
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
-webkit-transform: scale(0.5);
transform: scale(0.5);
border-style: solid;
border-width: 1px;
border-color: red;
}
</style>
</head>
<body>
<div class="btn"></div>
</body>
</html>
