Assign a class to the submit button

Good morning, everyone,

I am trying to figure out how to assign one or more classes present in my template to the Submit button.

I work on Joomla 5 with Yootheme

The button generates me these classes by default:

<button class=“nui button colored slate” name=“submit” value="” id=“submit” type=“submit” >

If I enter in the HTML Attributes settings with this code:

class=el-content uk-width-1-1 uk-button uk-button-secondary uk-button-large

I get is this:<button class=“nui button colored slate el-content uk-width-1-1 uk-button uk-button-secondary uk-button-large&quot;” name=“submit” value="” id=“submit” type=“submit” >

How can I apply only my classes?

Thanks

Marco