better-looking login inputs on iPhone

**Before:**

![iphone-before](https://f.cloud.github.com/assets/814637/286443/b55dbec6-923c-11e2-9bfd-e605335b9a09.PNG)

![ipad-before](https://f.cloud.github.com/assets/814637/286429/5d6ece44-923c-11e2-8802-57fe2c852b89.PNG)

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**After:**

![iphone-after](https://f.cloud.github.com/assets/814637/286428/5b9ff9e4-923c-11e2-95dd-fb5318128a9a.PNG)

![ipad-after](https://f.cloud.github.com/assets/814637/286427/5a201126-923c-11e2-9ce2-4704db44c038.PNG)