Two articles are linked by MoT. Besides reading those, I came across Sally Shepard. She is an accessibility consultant and an iOS developer. After watching the following talk I understood more –
Task: Use a tool like WAVE to scan a web page for accessibility problems.
I have never used WAVE before, so I was playing around with it, scanned more sites. Results are rather frightening. Can hardly find any site in which no error is flagged by this tool. It could be a challenge too: find a site that passes wave accessibility scan.
From the wave report I learnt more on style and contrast related errors.