Miscellaneous Layout and Style fixes and cleanups

Description

This PR completes a number of layout fixes and other improvements, mostly from the P1 (but also P2) list items:

Content aligns to the logo in small screens
Content aligns to the search bar on large screens,
Header height consistent between screen sizes
Overall spacing is consistent between screen sizes
Search bar is now fully flexible (as in the screen shots we sent), but the inside is now correctly aligned.
The inside of the mega-menu drop-down is now aligned to the logo always, and takes up the proper amount of space.
The mega-menu now correctly allows for the "secondary section" of the mega-menu if one is included (right now, none are).
Scroll bar fix
Missing rounded corners on pictures for the carousel
Clean up of the carousel section in the home screen
Overflow removed on scatter / map viz.
Page scroll not reset after window resize
Significant cleanup and improvements to the mobile menu to that it handles screen resizing more gracefully.