I am trying to create a toggle that disables one class connected to a tag similar to the theme toggle I already have. Turning it off would disable the colored text for easier reading (I like it, others might not). How would I go about doing this?

I am trying to create a toggle that disables one class connected to a tag similar to the theme toggle I already have. Turning it off would disable the colored text for easier reading (I like it, others might not). How would I go about doing this?

I am starting to learn and I am coding a frontend mentor challenge which is almost done and the repository is here https://github.com/cristianccgg/Age-calculator-app-main.git. It is an age calculator and I want the error messages to show when the input is not a number or when the number exceeds the days of the month etc, by using toggle to the class which hides and show the error. However the error messages are shown when the opposite happens, I mean when the input is a correct number between the days of the month, or the 12 months etc. I tried changing the logic to the opposite but that way the errors are always showing so I am not sure what I am doing wrong. Thanks!