fixes #8469 - css cleanup, whitespaces and remove dead code

I'd remove the filter attribute if we don't support IE < 9. (IE >= 9, support ``` -ms-linear-gradient```.
Additionally, I'd change the ```background-image``` to ```background``` and add a default ```background``` to none supporting browsers.
So it would all look like:
```css
background: #EEE; // for non supporting browsers
background: linear-gradient(top, whiteSmoke 0%, #EEE 100%); //HTML5 default
background: -webkit-linear-gradient(top, whiteSmoke 0%, #EEE 100%); 
background: -ms-linear-gradient(top, whiteSmoke 0%, #EEE 100%);
background: -o-linear-gradient(top, whiteSmoke 0%, #EEE 100%);
```