/*progressive underlying*/
.menu a{
position:relative;
}
.menu a:before{
content:"";
position:absolute;
width:100%;
height:1px;
bottom: 0;
left:0;
background-color: var(--yellow);
visibility: hidden;
transform: scaleX(0);
transition : all 0.5s ease-in-out 0s;
}
.menu a:hover:before{
visibility: visible;
transform: scaleX(1);
}