flexbox

Firstly I made the root div fit the screen by giving it the attribute "height: 100vh;". I then used flexbox to make the root div show the items in a colum by adding "display: flex; flex-direction:column;". The last thing I added was "flex: 1;" to the content div which is equivalent to "flex: 1 1 0;" This means "flex-grow : 1; flex-shrink : 1; flex-basis : 0;". Grow and shrink make the div grow and shrink in same proportion as the window-size. Basis makes the div take up screen as per the screen size available. For example if there are 4 divs with this they will all take up 25% of the available space.