openmct/platform/commonUI/general/res/templates/message-banner.html

<div class="l-message-banner s-message-banner">
    <span class="label">
        Objects not saved
    </span><span
        class="l-progress-bar s-progress-bar"
        ng-class="{ indeterminate:true }"><span class="progress-amt-holder">
        <span class="progress-amt" style="width: 35%"></span></span>
    </span><a class="l-action s-action">
    Try Again
</a><a class="ui-symbol close">
    &#x78;
</a>
</div>