⌘F
, so you can for instance interact with a webpage and quickly capture the hover colour of a link.⌘⇧X
will copy the colour as 8-bit hexadecimal; ⌘⇧R
and ⌘⇧A
will copy as CSS RGB or RGBA snippets respectively; ⌘⇧N
copies an NSColor snippet; and ⌘⇧U
copies a UIColor snippet.⌘⇧H
to 'hold' a colour. The picker stops updating and whatever colour you had selected fills the preview window. Sliders appear with the appropriate values set to describe the colour you've selected. As you can see from the image, the colour #f2efe6
is shown as HSB. From here it's possible to tweak the colour by changing the H, S or B values; swap between display types and you'll see the sliders and values update, allowing you to edit in RGB or HSL if you'd prefer. I often find it useful to pick a colour from a design I'm working on, then play around with the HSB values in order to create a lighter or darker colour variant to be used for hover or interaction states for buttons and links.⌘V
and the Classic Color Meter will jump to hold mode and set the colour to the one you've pasted. Useful for tweaking colours without having to pick it first.