Alan/fix styling issues

[Rayuaz]

What does this PR do?

• Adds a background to the header cards on all inner pages.
• Fixes many styling issues related to rich text element, such as lists not having styles.
• Tweaks spacings issues throughout the app.
• Reduces repetitiveness by creating a uSurface utility class for surfaces.

Additional Notes

Home

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Package Page

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Privacy Policy Page

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404 Page

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Review checklist

Before submitting your PR, please review the following:

• I have read the CONTRIBUTING.md file.
• My changes are focused and address a single concern.
  • Debatable, but the changes are pretty interdependant and don't involve any logic, only styles.
• I have added/updated tests that prove my fix is effective or that
  my feature works.
• New and existing tests pass locally with my changes.
• I have added necessary documentation or made changes to
  documentation (if appropriate).
• My changes generate no new warnings or errors.
• My code follows the code style of this project.

Developer's certificate of origin

By submitting this pull request, I certify that:

• The contribution is my own original work.
• I have the right to submit it under the project's license.
• I understand and agree to the project's contributing guidelines.

[Rayuaz]

We were using 1.125rem as the text size pretty much everywhere, so I went ahead and made it the default (and set in on body instead of html because then it keeps the root element as 16px.

[Rayuaz]

Here I removed the classes on the text elements because they are not needed. It's just a rich text content and it's better to let the default styles handle them.

[Rayuaz]

Here I removed this unnecessary .package__instructionsSection section and added .uRichText to its parent, so it can handle the spacing with the default text styles.

[jamesponddotco]

LGTM 👍 Thanks!