The slotted element appears, but then doesn't disappear when the dom-if becomes false. 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. Try checking for existing elements in connectedCalback or by listening for slotchange events dispatched by your slot element ([HOST]Root. Slots allow to show elements from light DOM in specified places of shadow DOM. Note that when applying the restamp attribute to dom-if. . To access children assigned to slots in your shadow root, you can use the standard [HOST]edNodes or [HOST]edElements methods with the slotchange event. The slot is rendered correctly and everything appears to behave, except when flicking back and forth, once the earlier slot has been rendered. [HOST] › blog › introducing-shadow-dom-api. 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. There are two kinds of slots: Named slots: