make a underline with ::before css
.underline {
text-decoration: none;
position: relative;
}
.underline:after {
position: absolute;
content: '';
height: 2px;
/* adjust this to move up and down. you may have to adjust the line height of the paragraph if you move it down a lot. */
bottom: -4px;
/******
optional values below
******/
/* center - (optional) use with adjusting width */
margin: 0 auto;
left: 0;
right: 0;
width: 50%;
background: green;
/* optional animation */
-o-transition:.5s;
-ms-transition:.5s;
-moz-transition:.5s;
-webkit-transition:.5s;
transition:.5s;
}
/* optional hover classes used with anmiation */
.underline:hover:after {
width: 80%;
background: orange;
}