How to design your 404 error page with Nimble Builder
The Nimble Builder allows you to re-design any pages of any themes as you want. This includes the 404 page.
The example below is a screenshot of a 404 page built with the Nimble Builder.
1) If not done already, install and activate the WordPress Nimble Builder plugin.
2) Then, while logged in as administrator, visit whatever URL of your site that shows a 404. You can easily generate an error 404 by writing whatever incorrect url. For example : www.mysite.com/this_is_a_404_error_page. Replace www.mysite.com by your website address and you'll have a 404 error page.
4) Now you'll be able to add sections to the 404 page as for any other page using the Nimble Builder, or even to completely replace the content of the 404 page by selecting the "Nimble template" as template for the content, and a custom header and footer.