red rectangle after the contact form

Where can we see the website in question?

@takayukister one of the site https://dehijgendeherten.nl/contact/

Try switching to the default theme.

Why you are advised to deactivate plugins and switch to the default theme.

By switching to a default theme (twentytwenty) the style.css from the plug in is working. So all I have to do is to make the style.css working in the custom theme.

Do you have an idea how I do that?

@studioviv I don’t know how you’re writing your custom theme, but with mine, I just copied over the styles in /contact-form-7/includes/css/styles.css and included it in my custom theme. I have a folder called vendors that I use to include any third party styles.

@julianpark Thanks. I will try that