Sass (scss) retain mobile styles on desktop in a mobile-first approach

force-mobile-on-desktop

.btn-container{
    overflow: hidden;
    
    .btn,
    &.desktop .btn{
        width: 49%;
        margin: 5px 0;
        float: left;

        &:first-child{
            margin-right: 1%;
        } 

        &:last-child{
            margin-left: 1%;
        }
    }

    .btn{
        @media screen and (min-width: 768px){
            width: auto;
            float: none;
        }
    }
}