OfficialSite/assets/styles/base/_headings.scss

// ==========================================================================
// Headings
// ==========================================================================
@mixin h {
    margin-top: 0;
    line-height: $heading-line-height;
}
.o-h {
    @include h;
}

h1, .o-h1 {
    @extend .o-h;

    font-size: rem($heading1);
}

h2, .o-h2 {
    @extend .o-h;

    font-size: rem($heading2);
}

h3, .o-h3 {
    @extend .o-h;

    font-size: rem($heading3);
}

h4, .o-h4 {
    @extend .o-h;

    font-size: rem($heading4);
}

h5, .o-h5 {
    @extend .o-h;

    font-size: rem($heading5);
}

h6, .o-h6 {
    @extend .o-h;

    font-size: rem($heading6);
}