Fixed layout and styling issues

[enakshi200codes]

HTML Changes:

1. Added responsiveness meta tag so that the webpage can be properly scaled and accessed on mobile devices.
2. Added semantic <main></main> element around the primary content of the webpage.
3. Linked the contact section to it's address id stored in <id="contact">.

CSS Changes:

1. Fixed horizontal overflow issue to avoid unwanted horizontal scrolling.
2. Removed the unnecessary vertical scroll bar while keeping vertical scrolling intact.
3. Improved navbar positioning and styling by anchoring it top and left. Also, changed it's background color for visual highlight.
4. Enhanced navbar hover interaction for proper visual highlight over mobile devices.
5. Added animated hero background
6. Updated footer background color for visual consistency.

[ayushman1210]

will review it shortly !!