fix: replace fixed px/vw units with flexible sizing in Functions (#132)

[rathod24-code]

What this PR does

Fixes #132

Replaces fixed px and vw units with flexible relative units in
Functions.css to improve layout on resized windows and split-screen views.

Changes made

• Replaced height: 100vh with height: auto in .functions-parent
• Added flex-wrap: wrap to .functions-parent
• Replaced width: 302px with width: 100% in .functions-heading
• Replaced height: 87vh and max-width: 20vw with max-height: 80vh,
  min-width: 220px, max-width: 400px, width: 100% in .functions
• Replaced all fixed px padding values with rem equivalents
• Changed overflow: scroll to overflow: auto

Tested on

• Windows, desktop browser, resized window and split-screen view

[rathod24-code]

Hi! I've submitted PR #194 to fix this issue. Please review when you get a chance.