background image credit @luciascarlet
$$\ce{$\unicode[goombafont; color:red; pointer-events: none; z-index: -10; position: fixed; top: 0; left: 0; height: 100vh; object-fit: cover; background-size: cover; width: 100vw; opacity: 1.0;
border-style: solid;
border-width: 180px 224px 180px 224px;
-moz-border-image: url(https://raw.githubusercontent.com/sinasun/sinasun/main/border.png) 180 224 180 224 round round;
-webkit-border-image: url(https://raw.githubusercontent.com/sinasun/sinasun/main/border.png) 180 224 180 224 round round;
-o-border-image: url(https://raw.githubusercontent.com/sinasun/sinasun/main/border.png) 180 224 180 224 round round;
border-image: url(https://raw.githubusercontent.com/sinasun/sinasun/main/border.png) 180 224 180 224 round round;
background-attachment: fixed !important;
background: linear-gradient(to bottom, rgba(0, 0, 0, 0.5), color(display-p3 0.5 0 0 / 0.5));
background: linear-gradient(to bottom, rgba(0, 0, 0, 0.5), rgba(128, 0, 0, 0.5));');]{x0000}$}$$