Because the color of the parchment is rather dark, white or near white is the only way to get enough contrast for text to be legible (if you're thinking of light text). The problem, as you have found, is that the pale, pastel colors look washed out against that background.
I think that you will find that a dark color will look best.
Alleon had some excellent suggestions if you do like he suggests and keep the colors muted.
If you blur the background and sample the color to find the average, it is #c8ae93. The direct inverse (compliment) of this color is #37516c, which is a nice unsaturated blue that still gives plenty of contrast. It's a darker version than what is on the web site.
I like the #1e4000 that Alleon suggests, perhaps even a little warmer like #2f3609. If you concentrate on colors in this area, I'm sure that you will fine one that works the way you want.
Browns and dark oranges (like he suggests) would also be good. To get a little different, try something like #330936.
Try this. Pick you three favorite colors and set you type three different ways. Close your project and let it set for an hour or two and open the project again. Your eyes will tell you right away which one works best.
BTW, I thought that your version of "parchment" not suitable with the images of sand and sea. It looks (to me) too much like dirty sand. Can you not find a suitable "sand" background?
