This is the outer iframe that has another iframe inside.

This is the shortcode of the red iframe:
advanced_iframe securitykey=”da39a3ee5e6b4b0d3255bfef95601890afd80709″ use_shortcode_attributes_only=”true” src=”//www.tinywebgallery.com/blog/advanced-iframe/demo-advanced-iframe-2-0/same-domain-wrapped-auto-height/same-domain-wrapped-iframe-1/same-domain-wrapped-iframe-2a?content-only=1&css=1″ height=”100″ width=”100%” onload_resize=”true” include_scripts_in_content=”true” style=”outline:1px solid red;” scrolling=”no” iframe_content_id=”body” iframe_content_styles=”background-color: #ffdddd;padding:10px;”