It is widely believed that black on yellow is the best colour combination for readability and visibility. Yellow and black does have the highest contrast, but high contrast doesn’t necessarily equal readability. It’s true that black and yellow might work well for road signs, police tape or door numbers painted on brick, but much less true for 8pt serif type on a computer monitor. It reminds me of the time when all the zebra crossings were yellow – highly visible on tarmac, especially in the rain. Then came the safety campaign for yellow raincoats for schoolkids (I can still hear that jingle: ‘wearing yellow raincoats is the best protection yet’), which of course was anything but safe – the kids in yellow raincoats all but disappeared on the matching yellow zebra crossings! It was a farce: the campaign was so successful that white raincoats were replaced by yellow ones, but there were so many accidents due to reduced visibility they had to make all the zebra crossings white!