Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="page">
  <section class="content">content</section>
  <aside class="sidebar">sidebar</aside>
</div>

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

@import "susy";

.page {
  @include container(1280px 16 show);
}

.content{
  @include span(10 of 16);
}

.sidebar{
  @include span(6 of 16);
  // or @include span(6 of 16 last);
  @include last;
}

SassMeister-output.css

.page {
  max-width: 1280px;
  margin-left: auto;
  margin-right: auto;
  background-image: linear-gradient(to right, rgba(102, 102, 255, 0.25), rgba(179, 179, 255, 0.25) 80%, transparent 80%);
  background-size: 6.32911%;
  background-origin: content-box;
  background-clip: content-box;
  background-position: left top;
}

.page:after {
  content: " ";
  display: block;
  clear: both;
}

.content {
  width: 62.02532%;
  float: left;
  margin-right: 1.26582%;
}

.sidebar {
  width: 36.70886%;
  float: left;
  margin-right: 1.26582%;
  float: right;
  margin-right: 0;
}

SassMeister-rendered.html

<div class="page">
  <section class="content">content</section>
  <aside class="sidebar">sidebar</aside>
</div>