header{position:fixed;top:50%;left:50%;transform:translate(-50%,-50%)}.nav-menu{position:relative;display:flex;align-items:center;gap:40px}.nav-menu li a{font-size:40px;color:#000}.nav-menu .nav-indicator{position:absolute;bottom:0;left:0;width:0;height:4px;background-color:#000;transition:all .4s ease;z-index:1;opacity:0}