.backdrop{background:rgba(0,0,0,.9);bottom:0;contain:strict;left:0;opacity:0;overflow:auto;position:fixed;right:0;-ms-scroll-chaining:none;overscroll-behavior:none;top:0;transition-property:opacity;visibility:hidden;z-index:-1}.backdrop_visible{opacity:1;visibility:visible;z-index:10}.backdrop_visible.backdrop_fading{opacity:0}