Generated by SassMeister.com.

SassMeister-input-HTML.haml

%div.container
  %div.primary
    %div.inner-content Inner Content
    %div.inner-content Inner Content
  %div.secondary Secondary Content

SassMeister-input.scss

// ----
// Sass (v3.4.6)
// Compass (v1.0.1)
// Breakpoint (v2.5.0)
// Susy (v2.1.3)
// ----

@import "breakpoint";
@import "susy";

$susy: (
  container: 960px,
  columns: 12,
  gutters: 1/6,
  output: isolate,
  debug: (
    image: show,
    color: rgba(blue, .125),
    output: background
  )
);

div {
  height: 100%;
  text-align: center;
  box-sizing: border-box;
}
.container {
  @include container;
  height: 98vh;
}
.primary {
  @include span(8 first);
  background-color: rgba(gray, .125);
}
.secondary {
  @include span(4 last);
  background-color: rgba(red, .125);
  padding: 1em;
}
.inner-content {
  @include span(2 of 8 at 2);
  background-color: rgba(yellow, .125);
  height: 100%;
  padding: 1em;
  &:last-child {
    @include span(2 of 8 at 6);
  }
}

SassMeister-output.css

div {
  height: 100%;
  text-align: center;
  box-sizing: border-box;
}

.container {
  max-width: 960px;
  margin-left: auto;
  margin-right: auto;
  background-image: linear-gradient(to right, rgba(0, 0, 255, 0.125), rgba(77, 77, 255, 0.125) 85.7142857143%, transparent 85.7142857143%);
  background-size: 8.4337349398%;
  background-origin: content-box;
  background-clip: content-box;
  background-position: left top;
  height: 98vh;
}
.container:after {
  content: " ";
  display: block;
  clear: both;
}

.primary {
  width: 66.265060241%;
  float: left;
  margin-left: 0;
  margin-right: -100%;
  background-color: rgba(128, 128, 128, 0.125);
}

.secondary {
  width: 32.5301204819%;
  float: left;
  margin-left: 67.4698795181%;
  margin-right: -100%;
  background-color: rgba(255, 0, 0, 0.125);
  padding: 1em;
}

.inner-content {
  width: 23.6363636364%;
  float: left;
  margin-left: 12.7272727273%;
  margin-right: -100%;
  background-color: rgba(255, 255, 0, 0.125);
  height: 100%;
  padding: 1em;
}
.inner-content:last-child {
  width: 23.6363636364%;
  float: left;
  margin-left: 63.6363636364%;
  margin-right: -100%;
}

SassMeister-rendered.html

<div class='container'>
  <div class='primary'>
    <div class='inner-content'>Inner Content</div>
    <div class='inner-content'>Inner Content</div>
  </div>
  <div class='secondary'>Secondary Content</div>
</div>