<h1>标题</h1>
<style>
h1 {
font-size: 30px;
position: relative;
line-height: 1;
display: inline-block;
margin-bottom: 35px;
}
h1:after {
position: absolute;
left: 0px;
bottom: -76.7857%;
width: 70%;
height: 5px;
background: #325dcf;
content: \'\';
}
</style>