Styling failed submitted forms

I have a non-styled HTML form which I hosed on a wordpress website, I’m able to style the form using CSS and HTML but when a value is missing it takes me to an InfusionSoft hosted form which doesn’t have the styling. I tried using JavaScript to block the button if any of the fields are missing but for some reason it’s not working!
Anybody had the same issue?
Thank you

Hi, @nasser_halabi. Can you link us to the page on your WordPress site with the form?