conference: Adjust sponsor bar for visual symmetry
This does a few things:
- Makes the content table fixed width, so we can adjust the relative sizes of the content and sponsor bar
- Fixes the right sidebar width and images, so we don't expand willy nilly to the right
- Makes the logos be fixed in width, adjusting scaling manually for logo aspect ratio to allow for a consistent visual size
- Adjust spacing between sponsors using padding instead of whitespaces, make things slightly tighter so there's less dead space
Edited by Arun Raghavan