The blackout banner is loaded by this script, http://meta.wikimedia.org/w/index.php?title=Special:BannerLoader&banner=blackout

This script create an #mw-sopaOverlay element which fills the viewport.

The page's usual content is not removed. Instead, the #content element and others are hidden by this CSS which is inserted by the blackout script.

    <style id="mw-sopa-blackout">
    #mw-page-base, #mw-head-base, #content,
    #mw-head, #mw-panel, #footer { display: none; }
    </style>

The "edit" links have been removed for normal users. Attempting to edit any page results in the message,

    The action you have requested is limited to users
    in one of the groups: Stewards, staff.