You can make it a bit more visible if you use the Stylus extension. Unfortunately Chrome (and probably Firefox quantum) doesn't let you apply css agent_sheets

You can make it a bit more visible if you use the Stylus extension. Unfortunately Chrome (and probably Firefox quantum) doesn't let you apply css agent_sheets (only user/author), so that style="display:none!important" on the iframes can't be overridden. If you use older Firefox or Palemoon then you can use Stylish v2.0.7 and override it. /* AGENT_SHEET */ iframe:hover{cursor:help!important} iframe{border:1px solid red!important;display:block!important} *{opacity:1!important}