ohif-viewer/Packages/viewerbase/components/viewer/loadingIndicator/loadingIndicator.html

<template name="loadingIndicator">
    <div class="imageViewerLoadingIndicator loadingIndicator">
        <div class="indicatorContents">
            <p>Loading... {{percentComplete}}</p>
        </div>
    </div>
    <div class="imageViewerErrorLoadingIndicator loadingIndicator">
        <div class="indicatorContents">
            <h4>Error Loading Image</h4>
            <p class='description'>An error has occurred.</p>
            <p class='details'></p>
        </div>
    </div>
</template>