Tweaked error overlay styles (pt2)

Created by: bvaughn

Follow up from PR #2201

I think I addressed the critical things and some of the nits, including:

• Moved margin between header and file name to header, so when content was scrolled, the header would remain more separate
• Made build-time and runtime overlays better match
• Secondary error <pre> style now uses yellow bg instead of red
• "Scrollable Header" (see above comment to why this is necessary) but I did increase the max-height from 35% to 50%.
• Fixed header and "X" button vertical alignment

Did not address:

• Selected Line Alignment (works for me)
• IE testing (no VM)

Runtime error (iOS)

Runtime error (desktop)

Build error (iOS)

Build error (desktop)