Why are my field so much wider when I view form on a phone in portrait?

Please see attached screen shot. My fields are super wide when i look at the form on a phone in portrait mode vs landscape, iPad and desktop. Is this a bug? 

Same form phone in landscape mode...

Since the forms are mobile responsive by default, the width of the fields shall be automatically adjusted based on the screen size. Please try adding the following CSS code to the form to display the fields at the same width in the portrait mode as well.

@media screen and (min-width: 10px) and (max-width: 540px){

    .form-textbox {

      width: 60px !important;

    }

}

Thanks!