Update Styling/Alignment on PageIndex Embedding

[ribbal]

Fix styling and alignment on PageIndex embedding to match the standard page index.

Standard Page Index Example:

Page Index Embedding Example:

Issues Fixed:

1. the single character column headings have a larger font than the standard page index
2. the columns do not extend to the full page width
3. the standard page index title displays slightly lower than a standard page title

[ribbal]

This shows the updated page index embedding following the fixes:

[redimp]

Hey @ribbal, thank you so much for taking care of the details!

I will review, test and merge as soon as I find time. I'm currently struggling to keep up. Please bring patience.