silk shirts: five sizes, in designer colours, for that special social occasion
What does "in designer colours" mean?
Yes, it's an odd one I've only heard it used quite recently - in the last 20 yrs or so. Perhaps someone with access to OED would check. It tends to refer to whatever fashion designers (people like Jasper Conran, Vivienne Westwood - people like that) happen to favour at the moment - often (usually - I'm not sure about this, and it may be different in the USA...) primary colours (bold reds and yellows and blues) but sometimes pastel shades.