Why "thank you messages" are not fully visible ?

Thank you messages are not fully visible on my website.

How can I check this issue ?

I checked your page and was unable to find a JotForm form embedded.  Is this the correct page for your form?

http://www.lyonembellissement.com/protected/?comeFrom=http%3A%2F%2Fwww.lyonembellissement.com%2Fnos-balades-1%2Fcalendrier-avril-2016-en-pr%25C3%25A9paration%2Fquais-joffre-et-tilsitt%2F&

Sorry, there is a password : avril2016

You can try adding this custom CSS code in your CSS tab under the Form Designer Tool.

.thankyou, #stage {

    height: 400px !important;

}

You can try experimenting the height value and see which one works for you best. Here's a screenshot where you need to paste the code in your Form Designer Tool.

Let us know if that works.

Thank for your answer. It is a good solution. But a bit complicated. I had to modify all my forms.

Unfortunately, I believe that would be the simplest and straight forward way to set the height of your "Thank You" page. You can just copy and paste the custom CSS code in the form Designer Tool.