:neckbeard: Update style.css, make label unselectable

If the user clicks on label, what we want to do is to change the input status. not to select the label text.
Update style.css

remove -o-user-select, -khtml-user-select, add -ms-user-select
Merge pull request #22 from camsong/patch-1

Update style.css, make label unselectable