I wrote a css override to make it more encouraging.
The code below makes the custom message you write look fancier, and removes the discouraging ! sign. I'd much rather block sites gently.
Thank you for such an awesome plugin though.

body {
background-image: url(https://source.unsplash.com/collection/139386/1920x1080/?sig=) !important;
background-repeat: no-repeat;
background-size: cover;

}
h1, table, #exception,#options, #switch,footer,header{
display:none !important;
}
#message {
width: 100%;
text-align: center;
font-size: 5em;
padding: 0 !important;
height: 100%;
display: flex;
align-items: center;
justify-content: center;
font-weight: 100;
background: #222222ba;
margin: 0 !important;
}

This is the best site blocking add-on.

Latest update has stopped the basic functionality from working

The new(er) version does not work well, after I load all my blocking page via a textfile, everything is working. But after a restart, I can see the blocked site, but when I click on a link from a blocked site (going to a sub link) it start blocking. When I save for example a new website to block, everything is working good again. But after a restart same problems. In the past I used it with succes, but now there is something not quite right.

Latest update make it unusable. Redirecting doesn't work - Address of the page repeated many times. I had pages blocking from 23 to 7 o'clock - an error pops up that the "from" parameter must be smaller than the "to" parameter.

This is a fantastic add-on but...

In the last update (0.4.4.1) the scheduled blocks appear to have become scheduled UNblocks and I can't see anywhere this change has been explained.

Aside from that, scheduled blocks are now unnecessarily complicated:

"By providing a regular expression rule, you can limit the current schedule to the matching URLs. To have multiple schedules with different rules, fill the section for each rule and press the save button. To delete a saved rule, fill the rule part and wait for the extension to load the schedule, then delete the timing section without removing the rule itself."

... wut?

Stopped working after updating, only works as long you set the master password every time you restart the browser, after restarting it stops working. Fixed by downloading previous version, thankfully all setting have transferred no problem.

I blocked a website just fine, but it keeps on sending me notifications, and on its horrible website there was nowhere to turn them off. Maybe I need to restart my computer, but that creates terrible problems nowadays. We'll see.

So far so good in the first 5 or so minutes. I needed it to stop me from accidentally watching any video sites while having a VPN with limited gb per month available.

Works pretty well, but after a few years of using it my list of blocked sites just DISAPPEARED. This is when I was logged in to my FF account as usual. Bizarre.

Fantastic! Does exactly what it says and there's lots more under the hood. A pity it's not compatible with Firefox Mobile.

I want instant close option than minimum 1sec.

I use pages where I read headlines of articles I might click, but some pages are behind walls or I do not like - this is a nice protection. The contra is that a page opens with the restriction info, which I must close then - a 5 seconds blend in info would be more comfortable for me - luxury problem. :-)

It's nice to be able to block sites I don't want from loading, but I wish there was an option to have those sites instantly close, rather than having to wait the 1 second.