When using the webmail on an iPhone there's an annoying little glitch which is easy to fix with a couple lines of CSS.  Basically, Safari on an iPhone will zoom any input field when it detects that the font-size of that field is less than 16px.  The downside of this is that for SmarterMail it throws off the layout a bit, and because it's a SPA the zoomed-in look persists until the user zooms out manually.

 

In my own responsive designs I've added the following CSS to prevent this behaviour:

@media screen and (-webkit-min-device-pixel-ratio:0) {
  select, textarea, input { font-size: 16px !important; }
    select:focus, textarea:focus, input:focus { font-size: 16px !important; }
}

 

 

Which is taken from this answer / discussion on StackOverflow:

https://stackoverflow.com/a/16255670

 

In the above CSS, I've removed the setting of the background-color on focus which was in the answer provided on StackOverflow which I figured SmarterMail wouldn't want to do because of your themes.