Sure! You can change the text colour of any of the screens however you like by adjusting the styles; all of the existing styling is meant to be changed to suit your project. I suggest you hover over the text in question and hit shift+i to find which styles are affecting it, or you can find the lines in achievements.rpy and just add color "#fff" or similar to whichever line of text you need. For example, you can change the line text a.description size 25 to text a.description size 25 color "#fff" to make the text white. Hope that helps!