On Physics' starting page, the color used for the topic texts is quite pale blue, #0587AC to a color picker.
Most pixels are even brighter than that because they are anti-aliased against the white background.
Such low-contrast texts might build barriers, reduce legibility and reading them is more fatiguing to the eye than necessary.
As an alternative, https://math.stackexchange.com is using a much darker color of #0F3559 which is much more comfortable.
The current color scheme on PSE is such that already followed links get darker, which is easier to read. Maybe something could be improved about this? Once there was a request due to hard noticeable color difference between fresh links and followed ones in Physics.SE color layout change, which is also a point to consider, but less important IMHO than legibility in the first place.