I used CM's button tool and just grabbed the inline css and stuck it into the submit button with GREAT results in most clients. I know the form doesn't work in Outlook but we know that going in. Problem is in ipads and iphones, it just strips parts of my inline css and seems to mix it with it's standard form submit button.
- on ipad
- should look like this + -

Here's my code

<input type="submit"  value="TAKE ME TO CHECKOUT >" style="background-color:#ff803a;border:1px solid #ff803a;border-radius:15px;color:#ffffff;display:inline-block;font-family:'Montserrat',Arial, Geneva, sans-serif;font-size:14px;font-weight:700;line-height:30px;text-align:center;text-decoration:none;width:220px;-webkit-text-size-adjust:none;mso-hide:all;" />