edx-platform/lms/static/sass/multicourse/_error-pages.scss

section.outside-app {
  @extend .container;
  @include text-align(left);
  padding: ($baseline*4) 0;

  h1 {
    @extend h2;
    margin-bottom: ($baseline*2);
  }

  p {
    max-width: 600px;
    margin: 0 auto;
  }
}