Hi there!
I’m new here on Mautic and in mjml/html 
and I need a little help on the code.
I need to add in all my e-mails the preview text (pre-header) and also use a breakpoint of 320px for my header. If I don’t use it, it gets messy and not mobile responsive.
I know that for add preview, I need to use this: Documentation for MJML - The Responsive Email Framework
And I know that for add the breakpoint, I need to use this: Documentation for MJML - The Responsive Email Framework
But I don’t know how to put it together 
Anyone?
I try to do this, but obviously, didn’t worked:
