【CSS】画个三角形或圆形或环

首先通过调整边框，我们可以发现一些端倪

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><style>.box{width: 150px;height:150px;border: 50px solid black;}</style><body><div class="box"></div></body>
</html>

接着我们通过调整各个边框（例如border-top）的属性后发现这些分割点棱角分明

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><style>.box {width: 150px;height: 150px;border-top: 50px solid cyan;border-right: 50px solid red;border-bottom: 50px solid green;border-left: 50px solid gray;}</style><body><div class="box"></div></body>
</html>

在把宽高都设为0后，发现这个图形逐渐清晰起来

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><style>.box {width: 0px;height: 0px;border-top: 50px solid cyan;border-right: 50px solid red;border-bottom: 50px solid green;border-left: 50px solid gray;}</style><body><div class="box"></div></body>
</html>

把任意两个三角形颜色设为一样，剩下的透明后就能获得三角形了

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><style>.box {width: 0px;height: 0px;border-top: 50px solid red;border-right: 50px solid red;border-bottom: 50px solid transparent;border-left: 50px solid transparent;}</style><body><div class="box"></div></body>
</html>