openmct/platform/commonUI/general/res/templates/controls/action-button.html

<a class="t-btn l-btn s-btn s-icon-btn s-very-subtle key-{{parameters.action.getMetadata().key}}"
   ng-class="{ labeled: parameters.labeled }"
   title="{{parameters.action.getMetadata().description}}"
   ng-click="parameters.action.perform()">
    <span class="ui-symbol icon">
        {{parameters.action.getMetadata().glyph}}
    </span>
    <span class="title-label" ng-if="parameters.labeled">
        {{parameters.action.getMetadata().name}}
    </span>
</a>