CSS Triangle

We can make a triangle with css, such as the following demo.

CSS code:

.arrow-up {
 width: 0;
 height: 0;
 border-left: 5px solid transparent;
 border-right: 5px solid transparent;
 border-bottom: 5px solid orange;
}
.arrow-down {
 width: 0;
 height: 0;
 border-left: 20px solid transparent;
 border-right: 20px solid transparent;
 border-top: 20px solid hotpink;
}
.arrow-right {
 width: 0;
 height: 0;
 border-top: 60px solid transparent;
 border-bottom: 60px solid transparent;
 border-left: 60px solid cyan;
}
.arrow-left {
 width: 0;
 height: 0;
 border-top: 10px solid transparent;
 border-bottom: 10px solid transparent;
 border-right:10px solid green;
}

HTML code:

<div class="arrow-up"></div>

<div class="arrow-down"></div>

<div class="arrow-left"></div>

<div class="arrow-right"></div>

Enjoy!