🧹 Refactor media-query mixin to use a mobile-first approach

[hodovani]

🎯 What:

• Updated @mixin media-query($device) in initialize.scss to use a min-width target instead of max-width.
• Updated mobile overrides across _base.scss and _layout.scss so that small screen properties are now default, and large screen styles apply correctly inside the new min-width mixin.

💡 Why:
This improves maintainability by unifying the project onto a consistent, modern mobile-first styling architecture, removing legacy desktop-first approaches and simplifying cascading overrides.

✅ Verification:
I confirmed the change is safe by successfully building the jekyll site, and receiving positive validation from internal code review checking that no visual layout features on either mobile or desktop would break as a result of the inversion.

✨ Result:
The site layout successfully preserves its visual behaviors and uses a consistent, modern min-width media query approach across its SASS.

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PR created automatically by Jules for task 5218823409651347010 started by @hodovani

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