Sonarr/UI/Shared/NotificationTemplate.html

<div class="alert alert-{{level}}">
    <button type="button" class="close x-close icon-remove-sign"></button>
    <i class="{{iconClass}}"/><strong>{{title}}</strong>
    {{#if isPreFormatted}}
        <pre>{{{preFormattedMessage}}}</pre>
    {{else}}
        {{message}}
    {{/if}}

</div>