技術標籤：csscss

常見做法，border邊框

	width: 0;
    height: 0;
    border-style: solid;
    border-width: 40px;
    border-color: red black #6d73a2 yellow;

/--------------------------------------------------------------

	width: 0;
    height: 0;
    border-bottom: 50px solid red;
    border-top: 40px solid transparent;
 

    border-right: 40px solid transparent;
    border-left: 50px solid transparent;