This is a template for Heroku error page showing your sleep hours for free dyno.
Heroku docs for setting custom error page is this:
If you need no change for this DEMO,
just run the following command:
heroku config:set \
ERROR_PAGE_URL=//notsobad-jp.github.io/herokusleep/
If you would like to customize the error page,
clone this repository and change it as you like.
The background color and text color are defined at about line 129.
The page design is from Better Error Pages by StatusPage.io.