Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="body">
<div class="ratio">
  <div class="fpp">
    <div class="fpp-inner">
        <div class="field--name-field-fpp-text-body"> More text perhaps, was on the dockett, we could never be sure. How many words will need to fit in the box?</div>
        <div class="field--name-field-fpp-text-url"> And what if there's more? What then?</div>
    </div> 
  </div>
</div>
</div>

SassMeister-input.scss

// ----
// Sass (v3.4.7)
// Compass (v1.0.1)
// ----

* {
  box-sizing: border-box;
}
@mixin vertical-center-with-ir (
  $inner-name: ".block-inner", 
  $inner-width: 80%, 
  $container-height: auto) 
  {
  #{$inner-name} {
    height: 100%;
    display: inline-block;
    vertical-align: middle;
    width: $inner-width;
    position: absolute;
    top: 0;
    left: (100% - $inner-width) / 2;
    &:before {
      content: '';
      display: inline-block;
      height: 100%;
      width: 0;
      font-size: 0;
      vertical-align: middle;
    }
  }
  #{$inner-name}-inner {
    display: inline-block;
    vertical-align: middle;
    width: 98%;
    text-align: center;
  }
}

///////////////////////////////////////
.body {
    max-width: 50%;
} 
.ratio {
  position: relative;
  height: 0;
  width: 100%;
  padding-top: percentage(1/3) !important; // this is the ratio of your container
  background: #eee;
  @include vertical-center-with-ir(".fpp");
}

SassMeister-output.css

* {
  box-sizing: border-box;
}

.body {
  max-width: 50%;
}

.ratio {
  position: relative;
  height: 0;
  width: 100%;
  padding-top: 33.3333333333% !important;
  background: #eee;
}
.ratio .fpp {
  height: 100%;
  display: inline-block;
  vertical-align: middle;
  width: 80%;
  position: absolute;
  top: 0;
  left: 10%;
}
.ratio .fpp:before {
  content: '';
  display: inline-block;
  height: 100%;
  width: 0;
  font-size: 0;
  vertical-align: middle;
}
.ratio .fpp-inner {
  display: inline-block;
  vertical-align: middle;
  width: 98%;
  text-align: center;
}

SassMeister-rendered.html

<div class="body">
<div class="ratio">
  <div class="fpp">
    <div class="fpp-inner">
        <div class="field--name-field-fpp-text-body"> More text perhaps, was on the dockett, we could never be sure. How many words will need to fit in the box?</div>
        <div class="field--name-field-fpp-text-url"> And what if there's more? What then?</div>
    </div> 
  </div>
</div>
</div>