.box{--border-width:var(--space-size-xs);background-color:var(--color-accent);border-left:var(--border-width) solid #0000;border-radius:2px;padding:var(--space-size-l);position:relative}.box:before{background-color:var(--color-brand-primary);border-radius:inherit;content:"";height:100%;left:calc(var(--border-width)*-1);position:absolute;top:0;width:var(--border-width)}