css怎么写梯形

{ border-bottom: 100px solid red; border-left: 25px solid transparent; border-right: 25px solid transparent; height: 0; width: 100px; }

通过css3的特性可以实现：
.t0{

    border-bottom: 80px solid #fb3;
    border-left: 30px solid transparent;
    border-right: 30px solid transparent;
    height: 0;
    width: 80px;
    margin: 0 0 10px 0;
  }

  .t1{
    border-radius: .3em .3em 0 0;
    margin: 10px;
    height: 30px;
    width: 80px;
    background: #fb5;
    transform-origin: bottom;
    transform: scaleY(1.1) perspective(.3em) rotateX(3deg);
  }