This article explains how you can use the and elements to create a flexible template that can then be used to populate the shadow DOM of a. Note that when applying the restamp attribute to dom-if. . The slotted element appears, but then doesn't disappear when the dom-if becomes false. As you can see, slot-based composition is a powerful tool that allows widgets to pull in the page content without cloning or modifying the DOM. Slots allow to show elements from light DOM in specified places of shadow DOM. There are two kinds of slots: Named slots: