How to make the text be in the sidebars, and the content between them (everything floats at the bottom)?

Question

css

Hello everyone, I have a problem. I'm doing website layout. I seem to have registered everything as it should, but I can’t make sure that the text is in the sidebars, and the content is in the middle! I did the borders with the help of a picture (if you know what I mean), I did it so that the borders do not end when you go down. At first, everything seemed to be normal, but then, when I started to prescribe a hat further, everything went wrong! I can't figure out what the problem is! The text lives for itself just below, when I start prescribing additions for page alignment, it seems to not see the first page, that is, it does everything from the bottom after the color one! Help me)