Thanks for updating in! I have checked your site and it turns out that you are trying to insert a modal popup form in your sidebar. Please understand that what you are doing is incorrect way of using the modal popup. Your sidebar is only 25% of the content area which is aproximately 250 pixel wide and your modal popup width is 750 pixels. Whatever we do with custom css, we cannot fit a 750 wide content on a sidebar that is only 250 wide.
If you want to use the full potential of the ConvertPlus and the modal popup, please check this out: https://theme.co/apex/forum/t/extension-convertplus/66
I am guessing that you want to display a form in your sidebar, you might want to check out Email Forms extension instead which you can check out here: https://theme.co/apex/forum/t/extension-email-forms/82
Hope this helps.