404 is not a standard page and you can't edit it from the page editor.


1. Text - if it is only the text, then you will find the strings in the .pot file.

If you haven't translated WordPress site,  this guide will help you out:

http://support.vamtam.com/solution/categories/2296/folders/9759/articles/194501-how-to-translate-a-vamtam-theme-in-other-language-


2. Styles - if you are developer you can change the page styles with the custom CSS in the Custom CSS are in General settings or change directly the template in a Child Theme:


http://support.vamtam.com/solution/categories/159995/folders/9759/articles/200025-how-to-add-custom-css-php-code-or-modify-the-theme-code-