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 './types/editor';

    a.btn-primary {
        color: $white;
    }

    img {
        border: 0;
    }
}