Shelf Background

Press START on the shelf and pick Theme. The background behind the panel shows each choice as you make it, and so does the bottom bar under it.

Row	Choices
Background	Grid (lines crossing, like squared paper), Plates (raised square plates, lit from the top left like a 16-bit floor), Dotted (dotted lines with a cross where they meet), Dither (the grid's squares shaded from the top left in an ordered dither), Rivets (the plates, riveted at each corner), Bits (square pixels scattered like a 1-bit picture), Solid (the colour alone), and Wallpaper when the card has one
Motion	Moving (the pattern drifts slowly to the side and loops without a seam) or Still. Every style but Solid and Wallpaper
Colour	Night, Slate, Navy, Teal, Green, Plum, Crimson or Amber
Font	Bold or Thin: how the big words on the bottom bar are drawn, CONTROLS and SETTINGS on the shelf, RETURN and CONFIRM in the menus

Left and Right change the lit row; B goes back. The default is a moving Grid in Night, close to black, with the bar's words in Bold.

The background is behind every screen, not only the shelf, and keeps moving while the screens slide over it. Colour also sets the colours of Settings and the other menus, the bars along the top and bottom: Night gives plain greys, Amber gives Mega Man Zero's own colours, and the others turn those to their hue. It does so with a wallpaper too.

Every pattern is pixel art on the same grid as the words over it: each of its pixels is 2x2 of the screen's, so nothing behind the shelf is smoothed.

A .png in Wallpapers/ on the card is shown as long as you have not picked another style, and stays one of the choices while the file is there.

Config/theme.txt

A theme.txt in Config/ on the card draws the top bar in colours of its own, one per line as a name and a hex colour: housing #242429 for the bar and edge #4d4d57 for its edge. Without the file, Colour sets the bars as above. The recess and opening lines coloured the cart slot under the shelf, which is gone; they are no longer read, and a file that still has them works as before.