Issue with submit color button

Hello, I have a problem with the submut button color.
In my form, I set the color b8f808 to be primary/hover/focus. On the preview form everything is ok, but when I put the form with shortcode, the button is with the default blue color, and I can’t change it.
Well.. I can, but I need to add a custom CSS. I just want to understand why the color is changing from the original form.