Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="container">
  <div class="sidebar">
    test
  </div>
  <div class="content">
    test<br />
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
  </div>
  
</div>

SassMeister-input.scss

// ----
// Sass (v3.3.4)
// Compass (v1.0.0.alpha.18)
// Susy (v2.1.1)
// ----

@import "susy";
@import "compass";
* {
 @include box-sizing(border-box);
}
.container {
  height: 100%;
  @include container(auto); 
}

.sidebar,
.content {
  height: 100%;
}

.sidebar {
  padding: 20px;
  background: #f3f3f3;
  @include span(200px of 8);
}

.content {
  margin-left: 200px;
  padding: 20px;
  background: pink;
}

SassMeister-output.css

* {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.container {
  height: 100%;
  max-width: 100%;
  margin-left: auto;
  margin-right: auto;
}
.container::after {
  content: " ";
  display: block;
  clear: both;
}

.sidebar,
.content {
  height: 100%;
}

.sidebar {
  padding: 20px;
  background: #f3f3f3;
  width: 200px;
  float: left;
  margin-right: 2.5641%;
}

.content {
  margin-left: 200px;
  padding: 20px;
  background: pink;
}

SassMeister-rendered.html

<div class="container">
  <div class="sidebar">
    test
  </div>
  <div class="content">
    test<br />
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
    test
  </div>
  
</div>