What a crimson screen is used for
- Rich red backgrounds for photography that avoid pure red’s harshness
- Attention and alert screens
- Warm-dark ambient light
Crimson screen online: #DC143C at full screen
Crimson is #DC143C — red high, with small amounts of green and blue that pull it slightly towards purple and take away the fluorescent quality of #FF0000. Pure red on a modern display is uncomfortably intense; crimson is what most people actually picture when they think of a deep red.
Because all three channels are active it is not a subpixel test. For that, use the pure red page, where green and blue are at zero.
How to get a full screen crimson background
Press the fullscreen button on the player above, or the F key. Escape returns you to the page. On a desktop browser F11 does the same job and hides the browser's own toolbars as well.
The colour box is a control, not a picture: use the hex field to enter any value, pick another shade from the palette, or download the current colour as a PNG at your screen's resolution. Whatever you set is written into the address bar, so the link you copy reproduces exactly what you are looking at.