lecampus.valdedrome.com/user/themes/lecampus/scss/theme/_menu.scss

header{
  nav{
    &.dropmenu{
      a{
        padding: 10px;
      }
      & > ul{
        @include inlineflex();
        width: 100%;
        -webkit-box-pack: center;
            -ms-flex-pack: center;
                justify-content: center;
        -webkit-box-align: center;
            -ms-flex-align: center;
                align-items: center;
        & > li{
          text-align: center;
          position: relative;
          margin: 0 10px;
          &>a{
            border-top: 1px solid $light-blue;
            border-bottom: 3px solid $green;

          }
          & > ul{
            display: none;
            width: 100%;
            position: absolute;
            margin-top: 12px;
            z-index: 0;
            z-index: 999;
            li{
              background-color: white;
              a{
                display: block;
                padding: 10px;
                position: relative;
                &:before{
                  content: "";
                  position: absolute;
                  width: 100%;
                  height: 3px;
                  bottom: 0;
                  left: 0;
                  background-color: $green;
                  visibility: hidden;
                  -webkit-transform: scaleX(0);
                          transform: scaleX(0);
                  -webkit-transition: all 0.3s ease-in-out 0s;
                  transition: all 0.3s ease-in-out 0s;
                }
              }
            }

          }
          &:hover{
            & > ul{
              display: block;
              li:hover{
                a:hover:before {
                  visibility: visible;
                  -webkit-transform: scaleX(1);
                          transform: scaleX(1);
                }
              }
            }
          }
        }
      }
    }
  }
}