CSS로 화살표 만들기

<div class="arrow-up"></div>
<div class="arrow-down"></div>
<div class="arrow-left"></div>
<div class="arrow-right"></div>

.arrow-up {
  width: 0;
  height: 0;
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-bottom: 5px solid black;
 }

 .arrow-down {
  width: 0;
  height: 0;
  border-left: 20px solid transparent;
  border-right: 20px solid transparent;
  border-top: 20px solid #f00;
 }

 .arrow-right {
  width: 0;
  height: 0;
  border-top: 60px solid transparent;
  border-bottom: 60px solid transparent;
  border-left: 60px solid green;
 }

 .arrow-left {
  width: 0;
  height: 0;
  border-top: 10px solid transparent;
  border-bottom: 10px solid transparent;
  border-right:10px solid blue;

**출처 : ** https://css-tricks.com/snippets/css/css-triangle/