css三角形

.tips:before { content: ''; border: 26px solid; border-color: #333; border-color: rgba(255,255,255,0); border-top-color: rgba(0,172,198,.8); position: absolute; left: 50%; top: 170px; margin-left: -26px; }

.wrapper:before {
border-color:#fd5f00 rgba(34,34,34,0) rgba(34,34,34,0);
border-style:solid;
border-width:8px;
content:"";
display:block;
margin-left:-4px;
margin-top:-1px;
position:absolute;
left:50%;
width:0
}