Realistically, just paint the bottom black; it's the easiest solution without creating more work and no extra benefit.

Is that cork above? You can buy cork wall tiles and glue on, or find a peel and stick flooring that's compatible.

As Skippack says, paint the bottom black. It will match the top.

@Skippack Tile & Stone and @apple_pie_order paint over the glue on the bottom?

It's rough and dingy.

@Seabornman I hadn't though of cork. Black would look best. Google says cork can be painted.

If you can sand off the glue, do that before painting or attaching cork. Cork needs a flat surface to adhere. If the glue can't be sanded off, use carpet again or cut-to-fit carpet tiles.

@apple_pie_order I just looked up rolled cork and will make phone calls today. sanding is too involved for the timing at-hand. Maybe just tear off the front?

I also think carpet will work and will make some calls looking for a black loop. Thanks

@Patricia Colwell Consulting I would like to think so. We would have, too. Problem is that the floor was tiled around the bar vs. underneath which is concrete..

There'd be a bar-shaped opening in the approx 14'x28' tile floor. It's a solid bar, and quite common in homes this age in this area.

I also scouted for rolled cork, vinyl fabric and carpet. I suspect it'll be quickest to replace the face boards and paint. I like the texture of the OSB but read it has a wax coating. A handyman will be here Monday afternoon. We'll see . . .

The OSB isn't bad. I'd paint the bottom and be done with it. It's not attractive and there isn't much you can do to make it attractive without spending way more money than you'll get back. Paint the bottom and be done. I don't think that cork, vinyl or carpet is going to make a difference. If you do a great installation, the improvement will be marginal. If your DIY job is mediocre, you'll have made things either worse or no better.