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Blue — #0000FF

Blue screen.

Blue, and nothing like the one with the sad face. Pure #0000FF.

01 — Panel

The panel

Any hex works. Patterns are drawn in CSS, so nothing blurs when the panel goes fullscreen.

#0000FF · Flat · 1920 × 1080

Colour
Any hex works. Patterns are drawn in CSS, so nothing blurs when the panel goes fullscreen.
Pattern

Link to this colour

The address bar already holds the colour and pattern. Send this to someone and they get the same panel.
02 — Uses

What this colour is for

Blue subpixel check
The third of the three. Blue subpixels fail less often than red, and when they do it's usually a faint one.
Night filters
Toggle night mode against this. The shift is obvious here and invisible on a photo.
Chromatic aberration
A flat blue field next to a dark edge makes purple fringing pop out of the corners.
Focus
Blue is the channel your eye focuses hardest on. A full blue field is the quickest way to feel that.
03 — Step by step

Testing a screen with it

  1. Brightness up

    Blue is dim to begin with; your eye is bad at it.

  2. Fullscreen

    Then check the corners, where blue uniformity fails first.

  3. Toggle your filter

    Watch what the OS does to the colour, not what the label on the switch says.

04 — FAQ

FAQ

Is this the Windows blue screen?

No. That one is #0078D7 and comes with a stop code.

Does a blue screen keep you awake?

Not really. Bright light does that, and the effect is small next to sleep, caffeine and timing.