Customising how your email appears on mobile devices is very easy with the Enudge drag and drop editor.

Firstly, while editing your campaign, use the desktop / mobile icons in the top left to choose how you are previewing:

While in mobile view, you will see that for some elements you can specify different measurements for mobile:

You can also turn on / off individual elements on mobile using the icons at the very bottom right corner:

Selecting a row also gives you access to additional settings for mobile, as shown below: