Add the following tag in your 404 page

<img alt="404" 
     src="https://illustatus.herokuapp.com/?title=Oops,%20Page%20not%20found&fill=%234f86ed"/>

• fill - controls the color
• title - controls the wording

and your'll get:

Or edit at the following URL

https://blairlee227.github.io/IlluStatus/

like this:

iro.js

MIT