It would be great to be able to express the size of the text in % based on the browser setting... this way the user could increase the size of the text in his browser (population is getting older) and all of our text would be increased automatically.

If not, could you give us some variables (like minsize, medsize, maxsize, ...) that we could set to x px and change when ever we need/want (my idea would be to give buttons to the user to give him the possibility of increasing the size of the text if needed, ex:  A  A  A ).