arrow up before content
&:before{
content:'';
border-style:solid;
border-width:10px;
border-color: rgba(255,255,255,0) rgba(255,255,255,0) rgba(0,0,0,0.7) rgba(255,255,255,0);
position:absolute;
left:50%;
margin-left:-5px;
top:-20px;
}