小三角
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<style>
.caret-down {
display: inline-block;
width: 0;
height: 0;
margin-left: 2px;
vertical-align: middle;
/* border-top: 4px solid black; */
border-bottom: 4px solid black;
border-right: 4px solid transparent;
border-left: 4px solid transparent;
}
</style>
</head>
<body>
<span class="caret-down"></span>
</body>
</html>
