.nav_bar ul li a:after {
width: 0;
height: 3px;
content: "";
position: absolute;
left: 0;
bottom: 10px;
background: #80d6f2;
transition: width .5s ease-in;
-moz-transition: width .5s ease-in;
-webkit-transition: width .5s ease-in;
-o-transition: width .5s ease-in
}