diff --git a/docs/_includes/version-banner.html b/docs/_includes/version-banner.html
index b2ef196837..1c9d52eb27 100644
--- a/docs/_includes/version-banner.html
+++ b/docs/_includes/version-banner.html
@@ -2,6 +2,6 @@
   <img src="/images/flame.svg">
   <p>
   lit-html is now part of the Lit library–see the new site at  <a href="https://lit.dev">lit.dev</a>.
-  This site documents lit-html 1.0, not the latest version.
+  This site documents lit-html 1.0, no longer the current version. 
   </p>
-</div>
+</div>
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 1fc8eac3bb..694ff014cf 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5,6 +5,7 @@
   "requires": true,
   "packages": {
     "": {
+      "name": "lit-html",
       "version": "1.4.1",
       "license": "BSD-3-Clause",
       "devDependencies": {
@@ -14,7 +15,7 @@
         "@typescript-eslint/eslint-plugin": "^2.26.0",
         "@typescript-eslint/parser": "^2.26.0",
         "@webcomponents/shadycss": "^1.8.0",
-        "@webcomponents/webcomponentsjs": "^2.4.2",
+        "@webcomponents/webcomponentsjs": "^2.6.0",
         "chai": "^4.1.2",
         "chromedriver": "^91.0.1",
         "clang-format": "~1.2.4",
@@ -1379,9 +1380,9 @@
       "dev": true
     },
     "node_modules/@webcomponents/webcomponentsjs": {
-      "version": "2.4.3",
-      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.4.3.tgz",
-      "integrity": "sha512-cV4+sAmshf8ysU2USutrSRYQkJzEYKHsRCGa0CkMElGpG5747VHtkfsW3NdVIBV/m2MDKXTDydT4lkrysH7IFA==",
+      "version": "2.6.0",
+      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.6.0.tgz",
+      "integrity": "sha512-Moog+Smx3ORTbWwuPqoclr+uvfLnciVd6wdCaVscHPrxbmQ/IJKm3wbB7hpzJtXWjAq2l/6QMlO85aZiOdtv5Q==",
       "dev": true
     },
     "node_modules/accepts": {
@@ -17010,9 +17011,9 @@
       "dev": true
     },
     "@webcomponents/webcomponentsjs": {
-      "version": "2.4.3",
-      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.4.3.tgz",
-      "integrity": "sha512-cV4+sAmshf8ysU2USutrSRYQkJzEYKHsRCGa0CkMElGpG5747VHtkfsW3NdVIBV/m2MDKXTDydT4lkrysH7IFA==",
+      "version": "2.6.0",
+      "resolved": "https://registry.npmjs.org/@webcomponents/webcomponentsjs/-/webcomponentsjs-2.6.0.tgz",
+      "integrity": "sha512-Moog+Smx3ORTbWwuPqoclr+uvfLnciVd6wdCaVscHPrxbmQ/IJKm3wbB7hpzJtXWjAq2l/6QMlO85aZiOdtv5Q==",
       "dev": true
     },
     "accepts": {
diff --git a/package.json b/package.json
index 7ba21e61bc..9a1687e02e 100644
--- a/package.json
+++ b/package.json
@@ -63,7 +63,7 @@
     "@typescript-eslint/eslint-plugin": "^2.26.0",
     "@typescript-eslint/parser": "^2.26.0",
     "@webcomponents/shadycss": "^1.8.0",
-    "@webcomponents/webcomponentsjs": "^2.4.2",
+    "@webcomponents/webcomponentsjs": "^2.6.0",
     "chai": "^4.1.2",
     "chromedriver": "^91.0.1",
     "clang-format": "~1.2.4",
diff --git a/src/env.d.ts b/src/env.d.ts
deleted file mode 100644
index b2cfd84bc2..0000000000
--- a/src/env.d.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-interface ShadyCSS {
-  nativeCss: boolean;
-  nativeShadow: boolean;
-  styleElement(host: Element, overrideProps?: {[key: string]: string}): void;
-  prepareTemplateDom(template: Element, elementName: string): void;
-  prepareTemplateStyles(
-      template: Element, elementName: string, typeExtension?: string): void;
-  ScopingShim: undefined|{
-    prepareAdoptedCssText(cssTextArray: string[], elementName: string): void;
-  };
-}
-
-interface ShadyDOM {
-  inUse: boolean;
-}
-
-interface Window {
-  ShadyCSS?: ShadyCSS;
-  ShadyDOM?: ShadyDOM;
-}
diff --git a/src/lib/dom.ts b/src/lib/dom.ts
index 5862f83c25..f986c8bc33 100644
--- a/src/lib/dom.ts
+++ b/src/lib/dom.ts
@@ -12,17 +12,12 @@
  * http://polymer.github.io/PATENTS.txt
  */
 
-interface MaybePolyfilledCe extends CustomElementRegistry {
-  readonly polyfillWrapFlushCallback?: object;
-}
-
 /**
  * True if the custom elements polyfill is in use.
  */
 export const isCEPolyfill = typeof window !== 'undefined' &&
     window.customElements != null &&
-    (window.customElements as MaybePolyfilledCe).polyfillWrapFlushCallback !==
-        undefined;
+    window.customElements.polyfillWrapFlushCallback !== undefined;
 
 /**
  * Reparents nodes, starting from `start` (inclusive) to `end` (exclusive),
diff --git a/src/lib/shady-render.ts b/src/lib/shady-render.ts
index 8ab1d449f3..97ef022d6b 100644
--- a/src/lib/shady-render.ts
+++ b/src/lib/shady-render.ts
@@ -311,6 +311,7 @@ export const render =
       // so we leave it up to the user to call `ShadyCSS.styleElement`
       // for dynamic changes.
       if (!hasRendered && needsScoping) {
-        window.ShadyCSS!.styleElement((container as ShadowRoot).host);
+        window.ShadyCSS!.styleElement(
+            (container as ShadowRoot).host as HTMLElement);
       }
     };
diff --git a/tsconfig.json b/tsconfig.json
index b1c49fb2c6..4775e3544a 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -18,6 +18,7 @@
     "noImplicitThis": true
   },
   "include": [
+    "node_modules/@webcomponents/webcomponentsjs/webcomponents-bundle.d.ts",
     "src/**/*.ts"
   ],
   "exclude": []