CSS实现三角形、梯形

//html
<div class="triangle-4"></div>

//css
.triangle-4 {
  width: 0;
  height: 0;
  display: inline-block;
  border-top: solid 100px red;
  border-right: solid 100px blue;
  border-bottom: solid 100px black;
  border-left: solid 100px salmon;
}