Fix 404 page styling responsiveness (#3575)

[vansh-commits]

Fixes #3575

Changes:
changed the styling of the 404 page not found to be responsive on mobile phones as well

Before:

After

I have verified that this pull request:

• [✅] has no linting errors (npm run lint)
• [✅] has no test errors (npm run test)
• [✅] is from a uniquely-named feature branch and is up to date with the develop branch.
• [✅] is descriptively named and links to an issue number, i.e. Fixes #123
• [✅] meets the standards outlined in the accessibility guidelines

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