Removing trailing whitespace and some excessive empty lines
Fixed "sub-flag-icon" ID being used many times on the same page
Fixed unclosed ".cover-overlay" divs
Minor fixes & improvements in code style, formatting, semantics etc.

Also, removing some unused (and duplicated) IDs and variables.
Merge pull request #364 from ArtemGordinsky/dev-0.3

Code cleanup: minor style, formatting, semantics improvements and fixes