discourse/app/assets/javascripts/wizard/templates/components/theme-previews.hbs

<ul class="grid">
  {{#each field.choices as |choice|}}
    <li>
      {{theme-preview colorsId=choice.id
                      wizard=wizard
                      onChange="changed"}}
      {{radio-button radioValue=choice.id
                     label=choice.id
                     value=field.value
                     onChange="changed"}}
    </li>
  {{/each}}
</ul>