[andybarton]

You just need to save the files at less than 930pixels at 72dpi on either side, in jpg format, with sufficient compression to be less than around 235kb. You should also use the sRGB colour space and nothing else.

There is only one colour space away web browser (Safari). All the others will only render sRGB colours correctly.

Trying to include an M8 profile will not make any difference.