<!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>Document</title>
<style>
.hr{
width: 300px;
background-color: #000;
}
.hr.half-px{
height: 0.5px;
}
.hr.one-px{
height: 1px;
}
.hr.scale-half{
height: 1px;
transform: scaleY(0.5)
}
</style>
</head>
<body>
<p>0.5px</p>
<div class="hr half-px"></div>
<p>1px</p>
<p class="hr one-px"></p>
<p>1px+scaleY(0.5)</p>
<div class="hr scale-half"></div>
</body>
</html>