When I ask a question on some of the new SE sites (and every answer has a check mark next to it for me to select one as my accepted answer), it's very hard for me to tell the difference between the check mark that I've checked, and one that I haven't checked. I'm red-green blind, and for me the green tone of the accepted answer is very hard to tell apart from grey checkmark that has not been checked.
I had this problem on Programmers SE, made a request, and they fixed it. I also had this problem on Tex SE, and made a request that's still not answered.
Could you add as a general guideline when designing new sites a requirement that the checkmark change shape in a noticable way when I click to accept an answer? (For example, getting noticably bolder, or having the unchecked check-mark be an outline like on Stack Overflow.)
Also, could you prod the appropriate person at Tex SE to fix this over there?