Make site mobile responsive

[ritorhymes]

Summary

This PR closes #19 and makes the site (all 3 pages) mobile responsive without changing the intended UI on desktop. No content has been edited.

A live demo can be tested here https://gitgitgadget.ritovision.com

What has changed

• Viewport tag added
• The header table is replaced with a responsive block display
• Left and right margin spacing reduced on mobile breakpoint
• Banner title decreased on small ≤450 screen sizes to fit without overflow behaviors
• Horizontal broken page scrolling caused by content not fitting on small screens is resolved by:
  • making image sizes responsive
  • making code blocks use overflow scroll
  • making long text strings break apart and wrap down to the next line as needed

Before and After Screenshots

Homepage - BEFORE

Homepage - AFTER

Architecture - BEFORE

Architecture - AFTER

Reply-to-this - BEFORE

Reply-to-this - AFTER

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Desktop Homepage - BEFORE

Desktop Homepage - AFTER

Notice the layout still looks and scales the same