HAI I just did this! key things for a scroll box is display: block; max-width and overflow: auto;

.scroll { display: block; height: 150px; max-width: 300px; overflow: auto; border: 9px solid !important; border-image: url('https://files.catbox.moe/1aq5ft.png') 5 fill round !important; background: transparent !important; margin: auto; }

also you just reminded me I urgently need to redo that url HELP