Soften the butter (1 cup) and mix 2 cups flour, 0.5 cups powdered sugar, and a pinch of salt. Press into greased 9x13 baking pan. Bake at 350 degrees for 20 minutes (330 degrees if you're using a glass dish).
Combine the 4 eggs, 2 cups powdered sugar, 0.5 cup lemon juice, 0.5 cup berry juice, 6 tablespoons flour, mixing well. Pour mixture over the previously baked bars. Place them back in the over for another 20 minutes.
Once the bars are cool, cut, sprinkle with powdered sugar, and enjoy!