Landing page layout changes + Focus changes

[michu2k]

Apart from the landing page changes, additional changes have been made to the focus styles. All common focus styles have been moved to the new utility class: ring-appearance defined in the tailwind.config file, so it should be easier to manage these values in the future as there is only one source of truth.

General:

• Adjusted fonts, so Poppins: 400 won't longer be needed
• Used the size class for elements with the same width and height
• globals.css: Added ring variable
• Replaced focus styles with .ring-appearance utility

Landing page:

• Rounded images & buttons
• Adjusted section spacing
• Added focus styles to the project images