The color scheme is blue on the front of the CAS background, while purple on the back. One example of a CAS background is the “Railway”, which allows you to create a sim on a runway. The colours in these backgrounds are typically muted and natural, but they can also be quite dramatic if you want to add custom content to your sim’s hairstyles. These backgrounds are simple, yet they can make a big impact, especially if you’re looking for a vintage look. They are a must-have if you love KawaiiĬAS backgrounds are simple for Sims 4 and are the easiest way to add colour to your sims’ worlds.