html.intro-pending{overflow:hidden!important;background:#000}
html.intro-pending body > :not(#first-visit-intro){visibility:hidden!important}
#first-visit-intro{position:fixed;inset:0;z-index:2147483647;background:#000;opacity:1;transition:opacity .4s ease}
#first-visit-intro iframe{display:block;width:100%;height:100%;border:0;background:#000}
#first-visit-intro.finished{opacity:0;pointer-events:none}
@media(prefers-reduced-motion:reduce){#first-visit-intro{transition:none}}