Generated by SassMeister.com.

SassMeister-input-HTML.haml

#subnav
  .container
    %ul#nav-subnav
      %li.nav-subnav-item
        %a.nav-subnav-link{href: '#'} Nav Item 1
      %li.nav-subnav-item
        %a.nav-subnav-link{href: '#'} Nav Item 2
      %li.nav-subnav-item
        %a.nav-subnav-link{href: '#'} Nav Item 3
      %li.nav-subnav-item
        %a.nav-subnav-link{href: '#'} Nav Item 4
      %li.nav-subnav-item
        %a.nav-subnav-link{href: '#'} Nav Item 5

SassMeister-input.scss

// ----
// Sass (v3.3.0.rc.1)
// Compass (v0.13.alpha.10)
// ----

@import "bourbon/bourbon";
@import "neat/neat";

#subnav {
  background-color: #ccc;
}

.container {
  @include outer-container;
  background-color: #eee;
}

#nav-subnav {
  @include row(table);
  margin: 0;
  padding: 0;
  .nav-subnav-item {
    display: table-cell;
    text-align: center;
    list-style-type: none;
  }
  .nav-subnav-link {
    text-align: center;
    display: block;
  }
}

SassMeister-output.css

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

#subnav {
  background-color: #ccc;
}

.container {
  max-width: 68em;
  margin-left: auto;
  margin-right: auto;
  background-color: #eee;
}
.container:after {
  content: "";
  display: table;
  clear: both;
}

#nav-subnav {
  display: table;
  width: 100%;
  table-layout: fixed;
  margin: 0;
  padding: 0;
}
#nav-subnav:after {
  content: "";
  display: table;
  clear: both;
}
#nav-subnav .nav-subnav-item {
  display: table-cell;
  text-align: center;
  list-style-type: none;
}
#nav-subnav .nav-subnav-link {
  text-align: center;
  display: block;
}

SassMeister-rendered.html

<div id='subnav'>
  <div class='container'>
    <ul id='nav-subnav'>
      <li class='nav-subnav-item'>
        <a class='nav-subnav-link' href='#'>Nav Item 1</a>
      </li>
      <li class='nav-subnav-item'>
        <a class='nav-subnav-link' href='#'>Nav Item 2</a>
      </li>
      <li class='nav-subnav-item'>
        <a class='nav-subnav-link' href='#'>Nav Item 3</a>
      </li>
      <li class='nav-subnav-item'>
        <a class='nav-subnav-link' href='#'>Nav Item 4</a>
      </li>
      <li class='nav-subnav-item'>
        <a class='nav-subnav-link' href='#'>Nav Item 5</a>
      </li>
    </ul>
  </div>
</div>