Modified exercises.html because of my new CSS3 exercises. Made new folder 'css/' to hold css exercise files. Modified link name (exercises) in homepage.
Added css folder. Added styling to homepage.
Added more styles and added navigation bar in the header of the homepage.
Fixed the transition for the links.
Removed the unnecessary spacing between the list items.
Further modified the horizontal navigation tabs and refined the transition effects.
Validation warning: added heading to the section text.
Revamped homepage to show big background and moved title down.
Fixed url of background image.
Modified homepage and added the working links in the navigation bar.
Set the background to not repeat.
Merge branch 'dev'