Hi there,
You might be able to use their exact same CSS:
.main-navigation li:after {
content: '';
display: block;
width: 0;
height: 0;
border-left: 1px solid #A27D50;
border-bottom: 1px solid #A27D50;
position: absolute;
top: 60%;
left: 50%;
opacity: 0;
-webkit-transition: height 1s 0.5s ease-in-out, width 0.5s ease-out, opacity 3s;
transition: height 1s 0.5s ease-in-out, width 0.5s ease-out, opacity 3s;
z-index: 99;
}
.main-navigation li:hover:after,
.main-navigation li.sfHover:after {
height: 15px;
width: 100vw;
-webkit-transition: height 0.5s ease-in-out, width 1s 0.5s ease-out;
transition: height 0.5s ease-in-out, width 1s 0.5s ease-out;
opacity: 1;
}
Not 100%, but it looks like it should work ๐