Fine-tune the theme preview to match mock

Normal: https://screenshot.googleplex.com/2JCGsaBfSQQ.png
Largest display and font size: https://screenshot.googleplex.com/HLy7WwEhhbu.png
Compared with Mock: https://screenshot.googleplex.com/7Pe96bWTCJo.png

Test: Manually
Fixes: 157402935
Change-Id: Iabebe50ad7d70f5c6f783cccd239153d4896262a
1 file changed