Hello, I was reading the lesson 'Responsive Web Design Certification > CSS > User Interface Design Fundamentals > How Do You Create Good Background and Foreground Contrast in Your Designs?’ and I noticed that the contrast ratios stated in the lesson are not corresponding with online validators or the tool in dev tools.
For example the color #4b4b4b on white background is stated there to be ~4.5:1, thus AA, but in dev tools it says to be 8.72:1, thus AAA (also on WebAIM checker I get the same result).
Also just down, #1a1a1a on white is stated as ~7:1, while is 17.4:1, and again down there #800080 on #0000cc is stated 1.48:1, while it is in reality 1.19:1. Those two last don’t affect much the overall meaning of the lesson, because still the contrast remain AAA in one case and not even AA in the other.
Is it maybe some old algorithm to calculate the contrast ratio, that now has been replaced? I don’t know if it is a problem for opening an issue, also I am quite a noob, actually I never opened an open-source issue, but it seemed to me worth of notice: what more expert users think about this?