how to make a full screen div, and prevent size to be changed by content?

Question

for my web application, i would like the main div to be full screen (both width and height = 100%), and regardless of content, i want it to stay at that size. that means, if

Answer 1

#fullDiv {
    height: 100%;
    width: 100%;
    left: 0;
    top: 0;
    overflow: hidden;
    position: fixed;
}