This tutorial explains how to change the backdrop colour of a game in WoofJS (so you can use a colour instead of an image for the backdrop). Create a new project at woofjs.com and add the following code. Make sure you pay attention to the comments in the code that explain how it works.
// You can set a backdrop colour using a hexadecimal colour code // Step 1 - Go to https://htmlcolorcodes.com // Step 2 - Select a colour // Step 3 - Copy the 'HEX' code including the # // Here is an example for a light green background... setBackdropColor("#76F67E") // PS. You have to spell color the American way in setBackdropColor // Hexadecimal (hex) is a number system that has 16 digits // These digits are numbers 0 to 9 and letters A to F. // Hex colour codes are six characters long. The hex system // allows us to create short codes for millions of different colours.