Theme CSS tidying.

A little more compact and improved readability:
- Replace 0px with 0.
- Compact and lowercase hex for colour (more consistent).
- Remove trailing whitespace.

Signed-off-by: Andrew <macbook-131@macbook-131s-MacBook-Pro.local>
Colorbox CSS - Remove IE6 hack.

Remove support for IE6 transparency hack. We don't include the required images anyway (so wasn't working). Plus: http://www.ie6countdown.com/

Signed-off-by: Andrew <macbook-131@macbook-131s-MacBook-Pro.local>
Thickbox CSS - Tidy up.

A little more compact and improved readability:
- Replace 0px with 0.
- Compact and lowercase hex for colour (more consistent).
- Remove trailing whitespace.
- Redundant color declaration removed for #TB_window.
- Trimmed down excessive comment blocks.

Signed-off-by: Andrew <macbook-131@macbook-131s-MacBook-Pro.local>
Product Rater CSS - Tidy up.

A little more compact and improved readability:
- Replace 0px with 0.
- Remove trailing whitespace.
- Remove commented out code.
- Deleted unused Star image (after code removal for IE).

Signed-off-by: Andrew <macbook-131@macbook-131s-MacBook-Pro.local>