Demon Skin Reminder (Classic Era)

Forgetting your armor buff after a death or a long fight is easy. Demon Skin Reminder shows a clear icon on screen whenever Demon Skin is missing. Click it, or press its hotkey, to cast it on yourself, and the reminder goes away.
Available for WoW Forever and WoW Classic Era. Download the file that matches your game: the file names and game versions on the Files tab tell them apart.
Features
Appears only when needed. It shows when Demon Skin is missing and hides once the buff is back. You can also keep it on screen all the time, dimmed while the buff is up.
Click or hotkey to cast. Assign any key (Shift, Ctrl and Alt combinations work). The key is taken off any action bar slot that used it, so there are no conflicts.
Movable and resizable. Drag it anywhere and resize it with the corner grip.
Custom text. Change the message under the icon, or hide it.
Optional transparent background.
Everything is saved between sessions.
How to use
Type /dsr to open the settings window, or use the minimap button or Options → AddOns → Demon Skin Reminder. Type /dsr help for the full command list.
Because of game rules, the reminder can't appear or disappear during combat. It keeps whatever it showed when the fight started and updates once combat ends.
Classic Era: Demon Skin and Demon Armor
In Classic Era you learn Demon Armor at level 20, the stronger version of Demon Skin. The Classic Era version picks this up from your spellbook automatically: once you know Demon Armor, clicking casts it (your highest rank), and either armor on you counts as buffed for as long as you still have Demon Skin. The settings window shows what's being tracked and what a click casts.
Disclaimer
Demon Skin Reminder is one of a few addons I came up with to make quality of life easier for myself during the WoW Forever beta test. The ideas are my own, and I did not search for, look at, or use any other author's addons, code or artwork before making them. Any resemblance to existing addons is coincidental.
Made for WoW Forever and WoW Classic Era. Released under the MIT license.