.modal{bottom:0;left:0;position:fixed;right:0;top:0;color:$modal_color;font-size:$modal_font_size_em;-moz-transition:background-color $modal_transition_duration_s;-o-transition:background-color $modal_transition_duration_s;-webkit-transition:background-color $modal_transition_duration_s;transition:background-color $modal_transition_duration_s;visibility:hidden}.modal--on{background-color:$modal_background;visibility:visible}