*{box-sizing:border-box}
html,body{margin:0;width:100%;height:100%;overflow:hidden;background:#f3f3f3}
html[data-theme=dark],html[data-theme=dark] body{background:#1e1e1e;color-scheme:dark}
#demo{position:absolute;left:50%;top:50%;width:820px;height:1064px;border:0;transform:translate(-50%,-50%) scale(var(--demo-scale,1));transform-origin:center}