I created a Fragment that is working perfectly, except it's not aligning to the center of the layout. I need to center the content in this

Code:
<mmx-text slot="main" part="detail fragment fragment__product_star_container" data-hide-on-empty="false" data-theme="1" data-theme-class="mm-theme-typography-paragraph-small" data-style="">...</mmx-text>
My first attempt was this (entered in the mmx-customizations file:
Code:
mmx-text::part(fragment__product_star_container) {text-align:center}
Second attempt
Code:
mmx-text::part(detail fragment fragment__product_star_container) {text-align:center}
What am I missing? TIA