如何画三角形

html代码：

<span class="san"></span>
<span class="san1"></span>
<span class="san2"></span>
<span class="san3"></span>
<span class="san4"></span>

css代码：

 .san{
            display: inline-block;
            width: 0;
            height: 0;
            border: 10px solid;
            border-color: black red gray greenyellow;
        }
        .san1{
            display: inline-block;
            width: 0;
            height: 0;
            border: 10px solid;
            border-color: black transparent transparent transparent;
        }
        .san2{
            display: inline-block;
            width: 0;
            height: 0;
            border: 10px solid;
            border-color: transparent black transparent transparent;
        }
        .san3{
            display: inline-block;
            width: 0;
            height: 0;
            border: 10px solid;
            border-color:  transparent transparent  black transparent;
        }
        .san4{
            display: inline-block;
            width: 0;
            height: 0;
            border: 10px solid;
            border-color:  transparent transparent transparent black;
        }