.nav-link{position:relative}.nav-link .underline{display:block;position:absolute;bottom:0;left:0;width:100%;height:2px;background-color:currentColor;transform:scaleX(0);transition:transform .3s}.nav-link.active .underline,.nav-link:hover .underline{transform:scaleX(1)}.navbar-nav .nav-link.active,.navbar-nav .nav-link:hover{color:#3c99e0!important}.navbar-nav .nav-link:not(:first-child).active,.navbar-nav .nav-link:not(:first-child):hover{color:#007bff}.back-to-top{position:fixed;bottom:-60px;right:20px;background-color:#3c99e0;color:#fff;padding:10px 20px;border:none;border-radius:5px;cursor:pointer;transition:background-color .3s,bottom .3s}.back-to-top:hover{background-color:#0056b3}