See the 3 screenshots below. There are several different green hex values amongst them however the CSS is declaring the correct hex (#A0CB3C), and the image has no colour profile data attached (saved for web from Sketch3).
Chrome Firefox Safari
My iMac has no special colour calibration for the display, and no special colour settings set that I'm aware of.
The issue is persistent on all non-Apple browsers. i.e. the colours are consistent in Safari (although still incorrect, that's the last screenshot), in all other browsers the green used for CSS applied content is different to the green in images. The hex doesn't colour-pick correctly in any browser.
My colleague sat next to me with a near-identical setup does not have this issue. So it's clearly something specific to my machine.
Where do I start?