#context a%extreme span {
    color: blue;
    font-weight: bold;
    font-size: 2em;
}

.notice, .error { @extend %extreme; }

.hidden %placeholder {
    margin: 0;
}

p {
    @extend #context;
    padding: 2em;
}

div { @extend .hidden; }

$layout-namespace: 'test';

%#{$layout-namespace}layout {
  color: red;
}

.layout {
  @extend %#{$layout-namespace}layout;
}