Hello,
You may use custom css code, for example, try to add this code in Theme Options > Styling > Custom css:
.home .banner .banner-subtitle:after {
content: '';
display: block;
height: 3px;
background: black;
position: absolute;
left: 15px;
top: 45%;
width: 0;
-webkit-transition: all 0.5s ease;
-moz-transition: all 0.5s ease;
-o-transition: all 0.5s ease;
transition: all 0.5s ease;
}
.home .banner:hover .banner-subtitle:after {
width: 34%;
}
https://gyazo.com/374db904f98131cb84cf7548af7a5a16
Regards