yes, i need 3 sections (the 3 containers) that expands horizontaly 100%, and then inside each of them, another div that is at the center.
basically as it is on the code, and it works in part, because the footer always stays at the bottom, the problem is: when there is few content, the footer remains at bottom (thats ok) but i need the "main-container" and "main" divs to always fill the space between header and footer. right now, if there is few content, the main-container and main divs fits to the contents, and so the wrapper (cyan color) shows up.
i mean, what i need is: the header always at top, the footer always at bottom, and the main-container (and also the main that is inside it) to fill all the space between them. so, the wrapper color (cyan) should NEVER be seen.