Expand Height of CSS Panel - Upfront (Spirit)

I've been playing around with the new Upfront/Spirit theme. Pretty amazing.

Anyway - question is around adjusting CSS entry panel. I'm doing a number of CSS adjustments and find the small height of the CSS panel that opens at the bottom of the window to be a bit restricting. Is there a way to expand the height of that panel?

Thought I could select the edge where the panel opens and drag it upward - but cannot.

Am I missing something?