Contrast is a number: the WCAG ratios, and two common misses
Whether text is readable enough is not a matter of taste. It is a ratio you can compute from two colour codes, and the web’s accessibility standard says where the line is.
Contrast & accessibility
Contrast ratios and tap target sizes: the WCAG numbers, and how to check them on your own store.
Tap targets: the size WCAG requires, and what thumb studies found
Most store traffic is a thumb on a small screen. The accessibility standard puts a number on how big a button must be, and one old study tells you why the number matters.