The page features visual headers, per date, but these headers are not semantic headers. These elements should use a semantic element.
<div class="mw-echo-ui-subGroupListWidget-header"> <div class="mw-echo-ui-subGroupListWidget-header-row"> <span class="mw-echo-ui-subGroupListWidget-header-row-title oo-ui-widget oo-ui-widget-enabled oo-ui-labelElement-label oo-ui-labelWidget oo-ui-labelElement" aria-disabled="false"> <span class="mw-echo-ui-datedSubGroupListWidget-title"> <span class="mw-echo-ui-datedSubGroupListWidget-title-primary">27 October 2016</span> <span class="mw-echo-ui-datedSubGroupListWidget-title-secondary"></span> </span> </span> <div class="mw-echo-ui-subGroupListWidget-header-row-markAllReadButton oo-ui-widget oo-ui-widget-enabled oo-ui-buttonElement oo-ui-buttonElement-framed oo-ui-iconElement oo-ui-labelElement oo-ui-buttonWidget oo-ui-element-hidden" aria-disabled="false"> <a class="oo-ui-buttonElement-button" role="button" tabindex="0" aria-disabled="false" rel="nofollow"> <span class="oo-ui-iconElement-icon oo-ui-icon-doubleCheck"></span> <span class="oo-ui-labelElement-label">Mark group as read</span> <span class="oo-ui-indicatorElement-indicator"></span> </a> </div> </div> </div>