Why is the transition: background red in syntax highlighting (Visual Studio)?

Question

I am a teacher and had a student ask why the "background" is red in color. This is in Visual Studio Code using the Dark+ theme. I have tried looking in the settings for syntax highlighting to identify different colors, but haven't had any luck. Same with browsing the web for this theme's color usage.

Answer 1

background is not an animatable property. More on this here.

You may use background-color instead.