用css画一个三角形

<style type="text/css">
.triangle{
    width: 0;
    height: 0;
    border-top: 50px solid #000;
    border-right: 50px solid #d00;
    border-bottom: 50px solid #333;
    border-left: 50px solid #f66;
    background: #ccc;
}
</style>
<div class="triangle"></div>