You appear to have changed /something/ since you don't even show the alternating dark/light background I've always seen.
Possibly they are definitions in your browser itself, or in your OS defaults. If my R-Pi web-server is working...
NOTE: My browser has been configured with a "minimum font size" larger than normal, and you can see what effect that had on the D-Star information box -- it overlaps the activity table just a hair. On the admin page, the CPU Load field writes over the first digit or two of the CPU temperature field. The dashboard is quite heavily tied to small font size since it does not scale with browser "minimum font size" settings, nor with changes in the browser window size.
On your image, it looks very much as if your background color (nominally white on my screen) is the same as the shaded/highlight colors in the table, while my table has light grey and dark grey. The text shadow color (in the table headings) appears to be the same as the text color itself (on mine, the text is white with a dark grey/red shadow).
I don't see anything explicit in the "source HTML" calling out colors, so that may be somewhere in the CSS stuff....
...
And it is...
The alternating rows are in the CSS tools page: BgOdd and BgEven, and HeadDrop appears to be the shadow color. Same for the text color(s). The Blue color for the callsign is likely defined in your browser for unvisited links.