Add responsive layout CSS styles for Login Form

See websharks/s2member#211
Re-add logo height to CSS style for Login Form

See websharks/s2member#211
Improvements to login form CSS for mobile devices

See websharks/s2member#211
Add !important property to div#login width

See websharks/s2member#211
Merge pull request #291 from websharks/feature/211

Feature/211