Aspect ratio divs with CSS background images

Question

I have images of equal aspect ratios (300px x 255px) in divs taking up ~31% of the width to make 3 columns on desktop/tablet, then full width on mobile. The images scale to

Answer 1

You could use % to set a padding taking width for reference to keep ratio. example : http://codepen.io/anon/pen/vNXgJp or http://codepen.io/anon/pen/VvKPMM (demos below)

.hotels {
  display: inline-block;
  width: 31.8%;
  vertical-align: top;
  margin-bottom: 22px;
  background: url(http://www.telodesign.com/test/cavallo-300.jpg) no-repeat red;
  background-size: 100% auto;
}
.hotels:before {
  content: '';
  padding-top: 85%;
  float: left;
}

<div class="hotels">
  Here's a title</div>

<div class="hotels">
  Here's a title</div>

<div class="hotels">
  Here's a title</div>

or

.hotels {
  display: inline-block;
  width: 31.8%;
  vertical-align: top;
  margin-bottom: 22px;
  background: url(http://www.telodesign.com/test/cavallo-300.jpg) no-repeat red;
  background-size: 100% auto;
}
.hotels:before {
  content: '';
  padding-top: 85%;
  display: inline-block;
  vertical-align: bottom;
  margin-left: -0.25em;
}
p {
  display: inline-block;
  width: 100%;
  text-align: center;
  background: rgba(0, 0, 0, 0.5);
  margin: 0;
  padding: 1em;
  box-sizing: border-box;
}

<div class="hotels">
  <p>Here's a title</p>
</div>

<div class="hotels">
  Here's a title</div>

<div class="hotels">
  Here's a title</div>

Answer 2

You could try using view widths to keep the proportions on resize:

HTML
<div class="hotels">
Here's a title</div>

<div class="hotels">
Here's a title</div>

<div class="hotels">
Here's a title</div>

CSS

.hotels {
  display: inline-block;
  width: 31.8vw;
  height: 26.3vw;
  vertical-align: top;
    margin-bottom: 22px;
  background-image:url(http://www.telodesign.com/test/cavallo-300.jpg);
   background-size: cover;
}