How do you stop a fieldset from changing height when you click the modify button?

Hey! So I noticed that the Blades in the Dark sheet had this neat effect where the Modify button on a fieldset doesn't change the height of the element. How is this achieved exactly? The sheet in GitHub is really difficult to follow because it has no line-breaks when I open it, so I couldn't make sense of it. These images should illustrate the effect I want to avoid:

If you look in the "Source" subfolder you can see the actual code with line breaks and everything, that could help things :). Anyway, there are probably many ways of doing it, but one way is to just give the .repcontrol div containg the buttons a fixed height equal to the height it has before Modify has been clicked.

Thanks again Jakob, that source-folder had what I was looking for. Unfortunately, I still can't figure it out. Doh. I guess I'll have to give it a more in depth look how it's accomplished here.

CTRL-F the sheet.css for ".repcontrol", one of the results should be what you are looking for.

I found it and got it working. It was actually really simple once I actually started reading the CSS-file. Here's how: .sheet-fieldset .repcontrol{ height: 20px; }