unexpected rounded corner on image

Hi,

I replaced the default submit button on the Contact 7 forms that I use on my site, and it looks fine on my computer, but for some reason I’m seeing one rounded corner on the “send” button image when I look at it on my iPad. Here’s the code I used to replace the button with my own image:

.wpcf7-submit { background: url(‘http://casaguadalupana.org/wp-content/uploads/2013/10/sendbutton.pink_1-e1381080757189.png’) top left no-repeat transparent; border: none; padding: 100px; margin: 0px; text-indent: -50000px; width: 100%; height: 100%; }

Any idea what the problem is? Here’s the website: casaguadalupana.org. Thanks for your help!