Fix class name

_alpha-banner.html

<!-- insert this after the #global-header block -->
<div class="alpha-banner">
  <p>
    <b>ALPHA:</b> This is a prototype – your <a href="">feedback</a> will help us to improve it. <a href="#">Find out more</a>
  </p>
</div>

_alpha-beta.scss

@import "../_colours";
@import "../_typography";

$alpha-colour: $pink;
$beta-colour: $orange;

@mixin phase-banner($state: alpha) {
  padding: 0.5em 0;

  @if $state == alpha {
    background-color: $alpha-colour;
  } @else if $state == beta {
    background-color: $beta-colour;
  }

  p {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 15px;

    color: $text-colour;
    @include core-16;
  }

  a, a:link, a:visited, a:active {
    color: $text-colour;
  }

  a:hover {
    color: $text-colour;
  }
}

@mixin phase-tag($state: alpha) {
  display: block;
  float: left;

  @if $state == alpha {
    background-color: $alpha-colour;
  } @else if $state == beta {
    background-color: $beta-colour;
  }

  color: #fff;
  @include bold-16;
  line-height: 20px;
  text-transform: uppercase;
  letter-spacing: 1px;
  text-decoration: none;

  margin: 3px 10px 0 0;
  padding: 2px 5px 0;
}

.alpha-banner {
  @include phase-banner(alpha);
}

.beta-banner {
  @include phase-banner(beta);
}