espocrm-base/client/res/templates/notification/list.tpl

<div class="page-header">
    <div class="row">
        <div class="col-sm-7">
            <h3>{{translate 'Notifications'}}</h3>
        </div>
        <div class="col-sm-5">
            <div class="pull-right btn-group">
                <button class="btn btn-default" data-action="markAllNotificationsRead" title="{{translate 'Mark all read'}}">{{translate 'Mark all read'}}</button>
                <button class="btn btn-default" data-action="refresh" title="{{translate 'checkForNewNotifications' category='messages'}}">&nbsp;&nbsp;<span class="fas fa-sync"></span>&nbsp;&nbsp;</button>
            </div>
        </div>
    </div>
</div>

<div class="row">
    <div class="col-md-8">
        <div class="list-container notification-list">{{{list}}}</div>
    </div>
</div>