html代码：
<div class="root1"></div>
<br>
<div class="root2"></div>
<br>
<div class="root3"></div>
<br>
<div class="root4"></div>
css代码：
.root1 {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 50px solid red;
}
.root2 {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-top: 50px solid blue;
}
.root3 {
width: 0;
height: 0;
border-bottom: 50px solid transparent;
border-right: 50px solid yellow;
border-top: 50px solid transparent;
}
.root4 {
width: 0;
height: 0;
border-top: 50px solid transparent;
border-left: 50px solid pink;
border-bottom: 50px solid transparent;
}
image.png
