title: Sizing width of an element as a percentage of its height or vice versa in a fluid design?
body: <p>Im making a responsive design, which has to keep the proportions of its elements (height to width) no matter what the screen size is, so i don't know the size in pixels for any of the elements and i can work only in %.</p>
  
  <p>I can set either the width or the height as a % of the browser size, but the i have no idea how to set the other property value.</p>
  
  <p>That using only CSS, making JS calculate the values is not an option. </p>