On contract to help develop the new Visual Studio 2012 launch site, today I had to override the default styling on an iOS textbox. With both an iPhone and iPad in hand I discovered the following post on SO.

http://stackoverflow.com/questions/2918707/turn-off-iphone-safari-input-element-rounding

It’s simple. Since Safari is a webkit browser you simply need to apply the following styles.

input { -webkit-appearance: none; border-radius: 0; }

There are a couple caveats but read up at the link above for more info.