Edit 20200628: Okay, time to get rid of this add-on. It breaks more and more sites all the time. Worse is, you don't know if the web site is broken or what!

Edit, 20200618: This addon BREAKS Paypal. It is certainly not nice to break a financial webpage. At Paypal I receive the message "Sorry about that! Looks like this action is not supported. Please return and report this error so that we support it in the future. (invalid client_id or redirect_url)". The error occurs when checking out an item on Ebay and selecting Paypay payment method.

This addon is good at what it does. However:
1. it is VERY SLOW, I find it much better than other "eye-saving" or "dark screening" addons. It's coloring options are much more comprehensive and it handles subtle shades of gray from the original web page well. (These often become indistinguishable with these addons.)
2. It breaks many pages
3. It needs a hotkey to disable/enable the current page. There are just too many things that become invisible too often.
4. The list of disabled pages needs to be sorted alphabetically.
5. The options page needs some cleanup and better explanation of what the options do.

Note: I was running FF 68. With that, I discovered DBLT (dark background light text) breaks the Zoom Page WE addon. Upgraded to FF74 and problem solved (with quick help from DBLT author!).