To make a custom background in JJS , the usual approach is to create your background image in an editor, export it as a PNG/JPG, and then import or assign it inside the project’s background settings or scene layer setup. In a JavaScript-style workspace, that often means loading the image and applying it as the page or scene background with CSS or a background asset slot.

Basic steps

  1. Create the background image in any design app.
  2. Export it in a web-friendly format like PNG or JPG.
  3. Add it to your project files or assets.
  4. Set it as the background in the editor or with code.
  5. Test the size, position, and scaling so it fits the screen properly.

If JJS uses code

A simple web-style background usually looks like this:

css

body {
  background-image: url("background.png");
  background-size: cover;
  background-repeat: no-repeat;
  background-position: center;
}

If the background is for a game or animated scene, it may need to be placed on a lower layer or given a fixed position so it stays behind everything else.

Good background tips

  • Use a wide image so it fits different screen sizes.
  • Keep important details away from the edges.
  • Use lower contrast if the background should stay subtle.
  • If you want movement, put the background on its own layer and animate that layer instead of the whole scene.

Forum-style version

Put the background asset on the back layer, keep it subtle, and make sure it scales to the screen size.
If you want it to move, group it separately and animate the group rather than the whole map.

The exact steps can vary depending on which JJS you mean, but the core idea is the same: create the image, import it, and assign it as the lowest visual layer or page background.

TL;DR: make the image, import it, and set it as the background layer or CSS background with cover/center settings.