代码如下:

triangle-up {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid red;
}

复制代码 代码如下:

triangle-down {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-top: 100px solid red;
}

复制代码 代码如下:

triangle-left {
width: 0;
height: 0;
border-top: 50px solid transparent;
border-right: 100px solid red;
border-bottom: 50px solid transparent;
}

复制代码 代码如下:

triangle-right {
width: 0;
height: 0;
border-top: 50px solid transparent;
border-left: 100px solid red;
border-bottom: 50px solid transparent;
}

复制代码 代码如下:

triangle-topleft {
width: 0;
height: 0;
border-top: 100px solid red;
border-right: 100px solid transparent;
}

复制代码 代码如下:

triangle-topright {
width: 0;
height: 0;
border-top: 100px solid red;
border-left: 100px solid transparent;
}

复制代码 代码如下:

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

复制代码 代码如下:

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