Screen Dimmer — Below Your Brightness Floor

Plate VII — black on a base40%

Tap for fullscreen · Esc brings you back

Dim amount 40%

Keys: F fullscreen · ↑↓ adjust dim · Esc exit

This isn't a brightness setting. It's a black layer painted over a color, so less light reaches your eyes — but the pixels underneath are still lit at whatever your hardware floor is. Real black behind an OLED still beats it. Where this genuinely helps: any panel whose "lowest" setting still feels bright once your eyes adjust to a dark room.

Why a browser can go lower than the slider

Your OS brightness control has a floor for a reason — go any lower and most panels start flickering or losing color accuracy, so manufacturers stop the slider well above zero. That floor is still, in a genuinely dark room, brighter than you want. Painting a translucent black rectangle over the display doesn't touch the backlight at all; it just asks fewer photons to leave the screen per pixel, arithmetically, the same way sunglasses work on a window. The result reads dimmer to your eyes even though the hardware never moved.

Picking a base color

White — general reading, checking the time, a light source you can dim down to almost nothing without switching colors.
Warm amber — softer on tired eyes than white at the same dim level; a reasonable substitute for a bedside lamp.
Night red — the classic astronomer's trick. Red light disturbs dark-adapted night vision the least, so if you need to check something without losing your eyes' adjustment to darkness, this is the one.