Magento Version: 2.3.4 Parent Theme: Luma

The issue I'm having is that I can't get any changes to work in the email styling. I have followed the docs about where to move what to move where however it isn't applying. I have even changed the css in the Luma source files and that doesn't change anything. I have attempted almost all the solutions I can find.

I believe it might be something to do with my /dev/tools/grunt/configs/themes.js however I am getting errors when running through the solution in this git issue:


Here is my themes config:

    nsu: {
        area: 'frontend',
        name: 'Optima/nsu',
        locale: 'en_US',
        files: [
        dsl: 'less'

My theme Less has been compiling fine, however I don't styles-m or styles-l in the theme, just styles.less.

The error thrown:

Running "exec:theme" (exec) task
Verifying property exec.theme exists in config...ERROR
>> Unable to process task.
Warning: Required config property "exec.theme" missing. Use --force to continue.

I'm running out of ideas on this and don't have the time left on the project to troubleshoot on guesswork. I would really appreciate any help given.


1 Answer 1


Please add your css in _email.less file. Below is the file path.


If _email.less is not exists on this file then copy it from the parent theme.

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