If you right-click any part of an output and then click inspect, you can often see code that will help you identify the style applied.
In this case I got this.
It's a default Azure Blue and it is white. That suggests something else you have changed in the header is affecting the text colour. I have shown the code as well in case you have sufficient knowledge to see what to change that would just affect the label.
As far as what you may have done to change the colour from the default white, this seems to be a likely cause.
If you change the Title Font Color, then both the title and Click here have that colour set here. What puzzles me is if you don't like the colour you have posted, the title would have the same problem.
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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.
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