Double Not_Valid class when invalidating Inputs

Double Not_Valid class when invalidating Inputs

  
Hi all,

I was checking my CSS when I stumbled upon something strange.
I have an input which I invalidated and when I look in the CSS it has twice the class Not_Valid, which means it has twice the CSS class associated with this class.
I made some screenshots.
Screen:

Inspector:

CSS:

Any of you an idea what can cause this?
Thanks!

BTW I'm working with the Liverpool theme
Solution
Martijn,

Even if the class appears twice, this shouldn't cause any problems given the way browsers apply the CSS. That said, how do you invalidate the input?
Solution
Hi Kilian,

I invalidate the input by setting the Input.Valite to False en setting the Input.ValidationMessage to "This is not valid"

The double class isn't a danger for preformance? Does he load the class twice?
Martijn,

There's no "loading" of a class. Don't worry, performance won't be affected :).