.topbar{
    position: absolute; left: 0; right: 0; top: 0;
    height: 4rem; width: 100%; margin: 0 auto;
    padding: .5rem 1rem; z-index: 1000;
    -webkit-transition: all .5s ease;
    -moz-transition: all .5s ease;
    -ms-transition: all .5s ease;
    -o-transition: all .5s ease;
    transition: all .5s ease;
}
.topbar.fixed{
    position: fixed;
}

.topbar .logo_wrapper{
    position: relative; height: 0;
    overflow: visible; display: block;
    z-index: 1002;
}

.topbar .logo_wrapper .logo{
    display: inline-block; height: 3rem; width: auto;
    position: absolute; left: 0; top: 0;
}


@media screen and (min-width:40em){
    .topbar{
        padding: .5rem 2rem;
    }
}