[Border-image generator] Longer image paths cause "CSS Code" box overflow

[jsnkuhn]

Longer image paths cause box overflow on fixed height "CSS Code" container. Still copy-able just visually a bit off:

The fixed heights look like an artifact of the float based layout used when border-image was new. Updating to grid/flex would be one way fix this.

[jsnkuhn]

the grid/flex fix seems to have taken care of this problem. So this is resolved