Fix grid and upcoming banner width and spacing to match jumbotron

[mattstratton]

Summary

This PR fixes layout inconsistencies on the homepage:

• The "Next Episode" (upcoming banner) and the grid container are now visually aligned and have the same width as the jumbotron.
• Added spacing between the jumbotron and the upcoming banner for better visual separation.
• Ensured all three sections use consistent container classes for a unified look.

Testing Steps

1. Run npm run build and view the homepage in exampleSite/public.
2. Confirm that the jumbotron, upcoming banner, and grid container are all the same width and visually aligned.
3. Confirm there is appropriate spacing between the jumbotron and the upcoming banner.

Context

• Addresses visual bugs where the grid and banner were wider or misaligned compared to the jumbotron.

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