silverstripe-webpack/app/client/src/scss/_typography.scss

// Add your site-wide, but not content editor typography styling

.bg-dark {
    h1, h2, h3, h4, h5, h6,
    .h1, .h2, .h3, .h4, .h5, .h6,
    .typography,
    a {
        color: $white;
    }
}

.typography {
    @include clearfix;

    @import "~ss-bootstrap-ui-webpack-boilerplate/src/scss/types/editor";
}