Gap under logo with default font size

[AlecRust]

On the Customize > Email Header page the header font size is set to a default value of 30px and the user can also add the “logo text”.

If you also add a logo image when the email is viewed in Gmail and probably other email clients there’s a 12px gap underneath the logo:

This gap is not there when viewed on the Customize page:

This looks to be due to the inline font-size: 30px set on the <h1> even though there is no text in this element only an image.

Please can you change this inline style to font-size: 0px when there is a logo image, which fixes the gap?