css - Responsive: how do I maintain proportions with stacked divs? -

I am creating a responsive site in which a resize is set to reset that image to me, the smaller, the image Have to be in the position of X, Y (it must be linked). My problem is how do I maintain the ratio of site ray size? I can define the width in percent, but what about height? EMS does not give me enough control for height (unless I am misunderstood in using them).

  .gallery {width: 100%; Status: Relative; }. Gallery-over {location: relative; Margin: -12.5em 0 0 69%; Width: 18.5%; } 
 
 I am quite certain that you are the only 'IMG' tag, but the height behavior You can also use percent when doing this W3C is the acceptable method according to W3C schools.