This is probably low-priority, but it seems like a bug. I was trying to put a line break into a class name as a workaround for #1081, annotating the class with a "stereotype".

However, the following code

A: "<<enumeration>>\nAlignment"{
    shape: class
    
    LeftAligned
    CenterAligned
    RightAligned
    Justified
}

built with

d2 --theme=200 -l elk filename.d2

results in a shape that looks like this:

It seems like the height of the class-name box has been adjusted for 2 lines, but the text doesn't actually wrap.