1、html
<body style="flex-direction: column; height: 600px;display: flex; justify-content: center; align-items: center;">
<!--向上的三角形-->
<div class="up"></div></br>
<!--向下的三角形-->
<div class="down"></div></br>
<!--向左的三角形-->
<div class="left"></div></br>
<!--向右的三角形-->
<div class="right"></div>
</body>
2、css
/*想获取朝那边三角形,给相反的一边设置颜色,font-size: 0;line-height: 0;可以兼容ie6*/
.up {
width: 0;
height: 0;
border-left: 20px solid transparent;
border-right: 20px solid transparent;
border-bottom: 20px solid #f00;
font-size: 0;
line-height: 0;
}
.down {
width: 0;
height: 0;
border-left: 20px solid transparent;
border-right: 20px solid transparent;
border-top: 20px solid #f00;
font-size: 0;
line-height: 0;
}
.left {
width: 0;
height: 0;
border-top: 20px solid transparent;
border-right: 20px solid #f00;
border-bottom: 20px solid transparent;
font-size: 0;
line-height: 0;
}
.right {
width: 0;
height: 0;
border-top: 20px solid transparent;
border-left: 20px solid #f00;
border-bottom: 20px solid transparent;
font-size: 0;
line-height: 0;
}
3、效果图