 <p><strong>Your question:</strong> Why would this happen?</p> <p><strong>A:</strong> Because <code>.divError</code> is in a stacking context and the root of that stacking context has a <code>z-index</code> (<em>calculated</em> or <em>explicitly declared</em>) lower than the root of the stacking context of the rest of the content that is 'over' <code>.divError</code>.</p> <p>If you want to know how to 'solve' this, the DOM tree leading to and surrounding the <code>updPanelContent</code> and positioning and z-index applied to those elements is needed.</p>