Added a new theme and extras

[Sandile-Dev01]

• Added a single new theme.
• Added min-width: 0 and min-width: 2400px for mobile up to 4K screens responsiveness, respectively.
• Added comments in the style.css file
• I realized that there was a lot of code hanging outside the media queries in the style.css file, I put it all in the inside media queries and only left the global one *, html outside.
• Deleted the media queries with no code inside
• I removed the styles in the style.css file pointing to ghost elements (elements that don't exist)
• Replaced some rem units with vw on the .intro and .tagline for responsiveness
• Added some hover effects on the icons
• Minimised the icon's number to 6 and sort them according to their relevance as well as style
• Replaced the tagline font with a complementary one
• Added <p> tags on the tagline, limited them to 3 and center-aligned them using flex-box on the main container.
• I also gave them a contrasting color to the header text the icons as well as the pipes | |
• I assigned them to a new font style.

Issue #36 solution and other issues I named above which were not yet open.