<!doctype html>
<link rel=help href="https://bugzilla.mozilla.org/show_bug.cgi?id=1741491">
<script>
  class CustomElement0 extends HTMLElement {
    constructor () {
      super()
    }

    static get observedAttributes () { return ["style"] }

    async attributeChangedCallback () {
      const animation = this.animate([{
        "boxShadow": "none",
        "visibility": "collapse"
      }], 1957)
      animation.commitStyles()
    }
  }

  customElements.define("custom-element-0", CustomElement0)
  window.addEventListener("load", () => {
    const custom = document.createElement("custom-element-0")
    document.documentElement.appendChild(custom)
    custom.style.fontFamily = "family_name_0"
  })
</script>
