diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
index 7e67c5144d..12d628cea5 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/__snapshots__/index.test.ts.snap
@@ -514,7 +514,7 @@ Object {
   \\"pluginId\\": \\"default\\",
   \\"version\\": \\"current\\",
   \\"label\\": \\"Next\\",
-  \\"banner\\": \\"none\\",
+  \\"banner\\": null,
   \\"badge\\": false,
   \\"className\\": \\"docs-version-current\\",
   \\"isLast\\": true,
@@ -1025,7 +1025,7 @@ Object {
   \\"pluginId\\": \\"community\\",
   \\"version\\": \\"1.0.0\\",
   \\"label\\": \\"1.0.0\\",
-  \\"banner\\": \\"none\\",
+  \\"banner\\": null,
   \\"badge\\": true,
   \\"className\\": \\"docs-version-1.0.0\\",
   \\"isLast\\": true,
@@ -1722,7 +1722,7 @@ Object {
   \\"pluginId\\": \\"default\\",
   \\"version\\": \\"1.0.1\\",
   \\"label\\": \\"1.0.1\\",
-  \\"banner\\": \\"none\\",
+  \\"banner\\": null,
   \\"badge\\": true,
   \\"className\\": \\"docs-version-1.0.1\\",
   \\"isLast\\": true,
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/versions.test.ts b/packages/docusaurus-plugin-content-docs/src/__tests__/versions.test.ts
index 0fad9a9217..fbf427889e 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/versions.test.ts
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/versions.test.ts
@@ -81,7 +81,7 @@ describe('simple site', () => {
       versionLabel: 'Next',
       versionName: 'current',
       versionPath: '/docs',
-      versionBanner: 'none',
+      versionBanner: null,
       versionBadge: false,
       versionClassName: 'docs-version-current',
     };
@@ -262,7 +262,7 @@ describe('versioned site, pluginId=default', () => {
       versionLabel: '1.0.1',
       versionName: '1.0.1',
       versionPath: '/docs',
-      versionBanner: 'none',
+      versionBanner: null,
       versionBadge: true,
       versionClassName: 'docs-version-1.0.1',
     };
@@ -554,7 +554,7 @@ describe('versioned site, pluginId=default', () => {
         routePriority: -1,
         tagsPath: '/docs/tags',
         versionPath: '/docs',
-        versionBanner: 'none',
+        versionBanner: null,
         versionBadge: false,
       },
     ]);
@@ -702,7 +702,7 @@ describe('versioned site, pluginId=community', () => {
       versionLabel: '1.0.0',
       versionName: '1.0.0',
       versionPath: '/communityBasePath',
-      versionBanner: 'none',
+      versionBanner: null,
       versionBadge: true,
       versionClassName: 'docs-version-1.0.0',
     };
@@ -750,7 +750,7 @@ describe('versioned site, pluginId=community', () => {
         routePriority: -1,
         tagsPath: '/communityBasePath/tags',
         versionPath: '/communityBasePath',
-        versionBanner: 'none',
+        versionBanner: null,
         versionBadge: false,
       },
     ]);
diff --git a/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts b/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
index 9972e6a96b..4c0495de73 100644
--- a/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
+++ b/packages/docusaurus-plugin-content-docs/src/plugin-content-docs.d.ts
@@ -11,7 +11,7 @@ declare module '@docusaurus/plugin-content-docs' {
 
 // TODO public api surface types should rather be exposed as "@docusaurus/plugin-content-docs"
 declare module '@docusaurus/plugin-content-docs-types' {
-  type VersionBanner = import('./types').VersionBanner;
+  export type VersionBanner = import('./types').VersionBanner;
   type GlobalDataVersion = import('./types').GlobalVersion;
   type GlobalDataDoc = import('./types').GlobalDoc;
   type VersionTag = import('./types').VersionTag;
@@ -22,7 +22,7 @@ declare module '@docusaurus/plugin-content-docs-types' {
     pluginId: string;
     version: string;
     label: string;
-    banner: VersionBanner;
+    banner: VersionBanner | null;
     badge: boolean;
     className: string;
     isLast: boolean;
diff --git a/packages/docusaurus-plugin-content-docs/src/types.ts b/packages/docusaurus-plugin-content-docs/src/types.ts
index 089b5bf84c..16f977883c 100644
--- a/packages/docusaurus-plugin-content-docs/src/types.ts
+++ b/packages/docusaurus-plugin-content-docs/src/types.ts
@@ -32,7 +32,7 @@ export type VersionMetadata = ContentPaths & {
   tagsPath: string;
   versionEditUrl?: string | undefined;
   versionEditUrlLocalized?: string | undefined;
-  versionBanner: VersionBanner;
+  versionBanner: VersionBanner | null;
   versionBadge: boolean;
   versionClassName: string;
   isLast: boolean;
@@ -65,12 +65,12 @@ export type PathOptions = {
 };
 
 // TODO support custom version banner? {type: "error", content: "html content"}
-export type VersionBanner = 'none' | 'unreleased' | 'unmaintained';
+export type VersionBanner = 'unreleased' | 'unmaintained';
 
 export type VersionOptions = {
   path?: string;
   label?: string;
-  banner?: VersionBanner;
+  banner?: 'none' | VersionBanner;
   badge?: boolean;
   className?: string;
 };
diff --git a/packages/docusaurus-plugin-content-docs/src/versions.ts b/packages/docusaurus-plugin-content-docs/src/versions.ts
index d73b26faf5..b4de0af428 100644
--- a/packages/docusaurus-plugin-content-docs/src/versions.ts
+++ b/packages/docusaurus-plugin-content-docs/src/versions.ts
@@ -264,10 +264,10 @@ function getDefaultVersionBanner({
   versionName: string;
   versionNames: string[];
   lastVersionName: string;
-}): VersionBanner {
+}): VersionBanner | null {
   // Current version: good, no banner
   if (versionName === lastVersionName) {
-    return 'none';
+    return null;
   }
   // Upcoming versions: unreleased banner
   else if (
@@ -291,17 +291,16 @@ function getVersionBanner({
   versionNames: string[];
   lastVersionName: string;
   options: Pick<PluginOptions, 'versions'>;
-}): VersionBanner {
-  const versionOptionBanner = options.versions[versionName]?.banner;
-
-  return (
-    versionOptionBanner ??
-    getDefaultVersionBanner({
-      versionName,
-      versionNames,
-      lastVersionName,
-    })
-  );
+}): VersionBanner | null {
+  const versionBannerOption = options.versions[versionName]?.banner;
+  if (versionBannerOption) {
+    return versionBannerOption === 'none' ? null : versionBannerOption;
+  }
+  return getDefaultVersionBanner({
+    versionName,
+    versionNames,
+    lastVersionName,
+  });
 }
 
 function getVersionBadge({
diff --git a/packages/docusaurus-theme-classic/package.json b/packages/docusaurus-theme-classic/package.json
index 0f3cf69a75..17b7d1c135 100644
--- a/packages/docusaurus-theme-classic/package.json
+++ b/packages/docusaurus-theme-classic/package.json
@@ -51,7 +51,9 @@
   },
   "devDependencies": {
     "@docusaurus/module-type-aliases": "2.0.0-beta.5",
+    "@types/mdx-js__react": "^1.5.4",
     "@types/parse-numeric-range": "^0.0.1",
+    "@types/rtlcss": "^3.1.1",
     "utility-types": "^3.10.0"
   },
   "peerDependencies": {
diff --git a/packages/docusaurus-theme-classic/src/index.ts b/packages/docusaurus-theme-classic/src/index.ts
index 7bf65db0f2..3097fe6cfa 100644
--- a/packages/docusaurus-theme-classic/src/index.ts
+++ b/packages/docusaurus-theme-classic/src/index.ts
@@ -10,7 +10,7 @@ import type {ThemeConfig} from '@docusaurus/theme-common';
 import {getTranslationFiles, translateThemeConfig} from './translations';
 import path from 'path';
 import Module from 'module';
-import type {AcceptedPlugin, Result, Plugin as PostCssPlugin} from 'postcss';
+import type {AcceptedPlugin, Plugin as PostCssPlugin} from 'postcss';
 import rtlcss from 'rtlcss';
 import {readDefaultCodeTranslationMessages} from '@docusaurus/utils';
 
@@ -25,7 +25,10 @@ const ContextReplacementPlugin = requireFromDocusaurusCore(
 // Need to be inlined to prevent dark mode FOUC
 // Make sure that the 'storageKey' is the same as the one in `/theme/hooks/useTheme.js`
 const ThemeStorageKey = 'theme';
-const noFlashColorMode = ({defaultMode, respectPrefersColorScheme}) => {
+const noFlashColorMode = ({
+  defaultMode,
+  respectPrefersColorScheme,
+}: ThemeConfig['colorMode']) => {
   return `(function() {
   var defaultMode = '${defaultMode}';
   var respectPrefersColorScheme = ${respectPrefersColorScheme};
@@ -83,7 +86,7 @@ const AnnouncementBarInlineJavaScript = `
   document.documentElement.setAttribute('${AnnouncementBarDismissDataAttribute}', isDismissed());
 })();`;
 
-function getInfimaCSSFile(direction) {
+function getInfimaCSSFile(direction: string) {
   return `infima/dist/css/default/default${
     direction === 'rtl' ? '-rtl' : ''
   }.css`;
@@ -183,13 +186,13 @@ export default function docusaurusThemeClassic(
         const resolvedInfimaFile = require.resolve(getInfimaCSSFile(direction));
         const plugin: PostCssPlugin = {
           postcssPlugin: 'RtlCssPlugin',
-          prepare: (result: Result) => {
+          prepare: (result) => {
             const file = result.root?.source?.input?.file;
             // Skip Infima as we are using the its RTL version.
             if (file === resolvedInfimaFile) {
               return {};
             }
-            return rtlcss(result.root);
+            return rtlcss((result.root as unknown) as rtlcss.ConfigOptions);
           },
         };
         postCssOptions.plugins.push(plugin);
diff --git a/packages/docusaurus-theme-classic/src/prism-include-languages.js b/packages/docusaurus-theme-classic/src/prism-include-languages.ts
similarity index 100%
rename from packages/docusaurus-theme-classic/src/prism-include-languages.js
rename to packages/docusaurus-theme-classic/src/prism-include-languages.ts
diff --git a/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx b/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
index 086186bb8b..65383d93e3 100644
--- a/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
@@ -18,49 +18,61 @@ import styles from './styles.module.css';
 
 import {useThemeConfig, parseCodeBlockTitle} from '@docusaurus/theme-common';
 
-const highlightLinesRangeRegex = /{([\d,-]+)}/;
+const HighlightLinesRangeRegex = /{([\d,-]+)}/;
+
+const HighlightLanguages = ['js', 'jsBlock', 'jsx', 'python', 'html'] as const;
+type HighlightLanguage = typeof HighlightLanguages[number];
+
+type HighlightLanguageConfig = {
+  start: string;
+  end: string;
+};
+
+// Supported types of highlight comments
+const HighlightComments: Record<HighlightLanguage, HighlightLanguageConfig> = {
+  js: {
+    start: '\\/\\/',
+    end: '',
+  },
+  jsBlock: {
+    start: '\\/\\*',
+    end: '\\*\\/',
+  },
+  jsx: {
+    start: '\\{\\s*\\/\\*',
+    end: '\\*\\/\\s*\\}',
+  },
+  python: {
+    start: '#',
+    end: '',
+  },
+  html: {
+    start: '<!--',
+    end: '-->',
+  },
+};
+
+// Supported highlight directives
+const HighlightDirectives = [
+  'highlight-next-line',
+  'highlight-start',
+  'highlight-end',
+];
+
 const getHighlightDirectiveRegex = (
-  languages = ['js', 'jsBlock', 'jsx', 'python', 'html'],
+  languages: readonly HighlightLanguage[] = HighlightLanguages,
 ) => {
-  // supported types of comments
-  const comments = {
-    js: {
-      start: '\\/\\/',
-      end: '',
-    },
-    jsBlock: {
-      start: '\\/\\*',
-      end: '\\*\\/',
-    },
-    jsx: {
-      start: '\\{\\s*\\/\\*',
-      end: '\\*\\/\\s*\\}',
-    },
-    python: {
-      start: '#',
-      end: '',
-    },
-    html: {
-      start: '<!--',
-      end: '-->',
-    },
-  };
-  // supported directives
-  const directives = [
-    'highlight-next-line',
-    'highlight-start',
-    'highlight-end',
-  ].join('|');
   // to be more reliable, the opening and closing comment must match
   const commentPattern = languages
-    .map(
-      (lang) =>
-        `(?:${comments[lang].start}\\s*(${directives})\\s*${comments[lang].end})`,
-    )
+    .map((lang) => {
+      const {start, end} = HighlightComments[lang];
+      return `(?:${start}\\s*(${HighlightDirectives.join('|')})\\s*${end})`;
+    })
     .join('|');
   // white space is allowed, but otherwise it should be on it's own line
   return new RegExp(`^\\s*(?:${commentPattern})\\s*$`);
 };
+
 // select comment styles based on language
 const highlightDirectiveRegex = (lang: string) => {
   switch (lang) {
@@ -123,9 +135,9 @@ export default function CodeBlock({
     ? children.join('')
     : (children as string);
 
-  if (metastring && highlightLinesRangeRegex.test(metastring)) {
+  if (metastring && HighlightLinesRangeRegex.test(metastring)) {
     // Tested above
-    const highlightLinesRange = metastring.match(highlightLinesRangeRegex)![1];
+    const highlightLinesRange = metastring.match(HighlightLinesRangeRegex)![1];
     highlightLines = rangeParser(highlightLinesRange).filter((n) => n > 0);
   }
 
diff --git a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
index 702e7a54ca..fd5f3fe331 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
@@ -35,7 +35,7 @@ function useShowAnnouncementBar() {
   return showAnnouncementBar;
 }
 
-function HideableSidebarButton({onClick}) {
+function HideableSidebarButton({onClick}: {onClick: React.MouseEventHandler}) {
   return (
     <button
       type="button"
diff --git a/packages/docusaurus-theme-classic/src/theme/DocSidebarItem/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocSidebarItem/index.tsx
index 98e109eceb..637f0d1846 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocSidebarItem/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocSidebarItem/index.tsx
@@ -26,7 +26,10 @@ import type {
 
 import styles from './styles.module.css';
 
-const isActiveSidebarItem = (item: Props['item'], activePath: string) => {
+const isActiveSidebarItem = (
+  item: Props['item'],
+  activePath: string,
+): boolean => {
   if (item.type === 'link') {
     return isSamePath(item.href, activePath);
   }
diff --git a/packages/docusaurus-theme-classic/src/theme/DocVersionBanner/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocVersionBanner/index.tsx
index eebbe862bd..948fa0cf04 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocVersionBanner/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocVersionBanner/index.tsx
@@ -21,6 +21,7 @@ import {
 
 import type {Props} from '@theme/DocVersionBanner';
 import clsx from 'clsx';
+import type {VersionBanner} from '@docusaurus/plugin-content-docs-types';
 
 type BannerLabelComponentProps = {
   siteTitle: string;
@@ -66,7 +67,7 @@ function UnmaintainedVersionLabel({
 }
 
 const BannerLabelComponents: Record<
-  Exclude<Props['versionMetadata']['banner'], 'none'>,
+  VersionBanner,
   ComponentType<BannerLabelComponentProps>
 > = {
   unreleased: UnreleasedVersionLabel,
@@ -75,7 +76,7 @@ const BannerLabelComponents: Record<
 
 function BannerLabel(props: BannerLabelComponentProps) {
   const BannerLabelComponent =
-    BannerLabelComponents[props.versionMetadata.banner];
+    BannerLabelComponents[props.versionMetadata.banner!];
   return <BannerLabelComponent {...props} />;
 }
 
@@ -156,11 +157,10 @@ function DocVersionBannerEnabled({versionMetadata}: Props): JSX.Element {
 }
 
 function DocVersionBanner({versionMetadata}: Props): JSX.Element {
-  if (versionMetadata.banner === 'none') {
-    return <></>;
-  } else {
+  if (versionMetadata.banner) {
     return <DocVersionBannerEnabled versionMetadata={versionMetadata} />;
   }
+  return <></>;
 }
 
 export default DocVersionBanner;
diff --git a/packages/docusaurus-theme-classic/src/theme/NavbarItem/DocsVersionDropdownNavbarItem.tsx b/packages/docusaurus-theme-classic/src/theme/NavbarItem/DocsVersionDropdownNavbarItem.tsx
index 2b48ada127..0b8688d72a 100644
--- a/packages/docusaurus-theme-classic/src/theme/NavbarItem/DocsVersionDropdownNavbarItem.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/NavbarItem/DocsVersionDropdownNavbarItem.tsx
@@ -16,9 +16,10 @@ import {
 import type {Props} from '@theme/NavbarItem/DocsVersionDropdownNavbarItem';
 import {useDocsPreferredVersion} from '@docusaurus/theme-common';
 import {translate} from '@docusaurus/Translate';
+import type {GlobalDataVersion} from '@docusaurus/plugin-content-docs-types';
 
-const getVersionMainDoc = (version) =>
-  version.docs.find((doc) => doc.id === version.mainDocId);
+const getVersionMainDoc = (version: GlobalDataVersion) =>
+  version.docs.find((doc) => doc.id === version.mainDocId)!;
 
 export default function DocsVersionDropdownNavbarItem({
   mobile,
diff --git a/packages/docusaurus-theme-classic/src/theme/NavbarItem/index.tsx b/packages/docusaurus-theme-classic/src/theme/NavbarItem/index.tsx
index 78c40909ea..5189c6e04f 100644
--- a/packages/docusaurus-theme-classic/src/theme/NavbarItem/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/NavbarItem/index.tsx
@@ -16,7 +16,9 @@ import type {Types, Props} from '@theme/NavbarItem';
 
 const NavbarItemComponents: Record<
   Exclude<Types, undefined>,
-  () => (props) => JSX.Element
+  // TODO: properly type this
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  () => (props: any) => JSX.Element
 > = {
   default: () => DefaultNavbarItem,
   localeDropdown: () => LocaleDropdownNavbarItem,
diff --git a/packages/docusaurus-theme-classic/src/theme/hooks/useTabGroupChoice.ts b/packages/docusaurus-theme-classic/src/theme/hooks/useTabGroupChoice.ts
index 1ddb0ebc9e..b1014cc3f6 100644
--- a/packages/docusaurus-theme-classic/src/theme/hooks/useTabGroupChoice.ts
+++ b/packages/docusaurus-theme-classic/src/theme/hooks/useTabGroupChoice.ts
@@ -21,11 +21,11 @@ const useTabGroupChoice = (): useTabGroupChoiceReturns => {
 
   useEffect(() => {
     try {
-      const localStorageChoices = {};
+      const localStorageChoices: Record<string, string> = {};
       listStorageKeys().forEach((storageKey) => {
         if (storageKey.startsWith(TAB_CHOICE_PREFIX)) {
           const groupId = storageKey.substring(TAB_CHOICE_PREFIX.length);
-          localStorageChoices[groupId] = createStorageSlot(storageKey).get();
+          localStorageChoices[groupId] = createStorageSlot(storageKey).get()!;
         }
       });
       setChoices(localStorageChoices);
diff --git a/packages/docusaurus-theme-classic/src/types.d.ts b/packages/docusaurus-theme-classic/src/types.d.ts
index 0f0711ae69..60ef940976 100644
--- a/packages/docusaurus-theme-classic/src/types.d.ts
+++ b/packages/docusaurus-theme-classic/src/types.d.ts
@@ -756,3 +756,18 @@ declare module '@theme/Tag' {
 
   export default function Tag(props: Props): JSX.Element;
 }
+
+declare module '@theme/prism-include-languages' {
+  import type * as PrismNamespace from 'prismjs';
+
+  export default function prismIncludeLanguages(
+    PrismObject: typeof PrismNamespace,
+  ): void;
+}
+
+declare module 'prism-react-renderer/prism' {
+  import type * as PrismNamespace from 'prismjs';
+
+  const Prism: typeof PrismNamespace;
+  export default Prism;
+}
diff --git a/packages/docusaurus-theme-classic/src/validateThemeConfig.js b/packages/docusaurus-theme-classic/src/validateThemeConfig.ts
similarity index 94%
rename from packages/docusaurus-theme-classic/src/validateThemeConfig.js
rename to packages/docusaurus-theme-classic/src/validateThemeConfig.ts
index 730bd317f1..4e15ff4688 100644
--- a/packages/docusaurus-theme-classic/src/validateThemeConfig.js
+++ b/packages/docusaurus-theme-classic/src/validateThemeConfig.ts
@@ -5,7 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const {Joi, URISchema} = require('@docusaurus/utils-validation');
+import {Joi, URISchema} from '@docusaurus/utils-validation';
+import type {ThemeConfig, Validate, ValidationResult} from '@docusaurus/types';
 
 const DEFAULT_DOCS_CONFIG = {
   versionPersistence: 'localStorage',
@@ -81,7 +82,7 @@ const DocItemSchema = NavbarItemBaseSchema.append({
   docsPluginId: Joi.string(),
 });
 
-const itemWithType = (type) => {
+const itemWithType = (type: string | undefined) => {
   // because equal(undefined) is not supported :/
   const typeSchema = type
     ? Joi.string().required().equal(type)
@@ -95,7 +96,7 @@ const itemWithType = (type) => {
 
 const DropdownSubitemSchema = Joi.object({
   position: Joi.forbidden(),
-}).when({
+}).when('.', {
   switch: [
     {
       is: itemWithType('docsVersion'),
@@ -150,7 +151,7 @@ const SearchItemSchema = Joi.object({
 
 const NavbarItemSchema = Joi.object({
   position: NavbarItemPosition,
-}).when({
+}).when('.', {
   switch: [
     {
       is: itemWithType('docsVersion'),
@@ -178,7 +179,7 @@ const NavbarItemSchema = Joi.object({
     },
     {
       is: itemWithType(undefined),
-      then: Joi.object().when({
+      then: Joi.object().when('.', {
         // Dropdown item can be specified without type field
         is: Joi.object({
           items: Joi.array().required(),
@@ -246,12 +247,12 @@ const CustomCssSchema = Joi.alternatives()
 
 const ThemeConfigSchema = Joi.object({
   // TODO temporary (@alpha-58)
-  disableDarkMode: Joi.any().forbidden(false).messages({
+  disableDarkMode: Joi.any().forbidden().messages({
     'any.unknown':
       'disableDarkMode theme config is deprecated. Please use the new colorMode attribute. You likely want: config.themeConfig.colorMode.disableSwitch = true',
   }),
   // TODO temporary (@alpha-58)
-  defaultDarkMode: Joi.any().forbidden(false).messages({
+  defaultDarkMode: Joi.any().forbidden().messages({
     'any.unknown':
       'defaultDarkMode theme config is deprecated. Please use the new colorMode attribute. You likely want: config.themeConfig.colorMode.defaultMode = "dark"',
   }),
@@ -329,8 +330,15 @@ const ThemeConfigSchema = Joi.object({
       'The themeConfig.sidebarCollapsible has been moved to docs plugin options. See: https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs',
   }),
 });
-exports.ThemeConfigSchema = ThemeConfigSchema;
 
-exports.validateThemeConfig = ({validate, themeConfig}) => {
+export {ThemeConfigSchema};
+
+export function validateThemeConfig({
+  validate,
+  themeConfig,
+}: {
+  validate: Validate<ThemeConfig>;
+  themeConfig: ThemeConfig;
+}): ValidationResult<ThemeConfig> {
   return validate(ThemeConfigSchema, themeConfig);
-};
+}
diff --git a/packages/docusaurus-theme-classic/tsconfig.json b/packages/docusaurus-theme-classic/tsconfig.json
index 583180dbf9..9840db7cfb 100644
--- a/packages/docusaurus-theme-classic/tsconfig.json
+++ b/packages/docusaurus-theme-classic/tsconfig.json
@@ -4,7 +4,6 @@
     "lib": ["DOM", "ES2019"],
     "module": "esnext",
     "noEmit": true,
-    "noImplicitAny": false,
     "jsx": "react",
     "baseUrl": "src"
   },
diff --git a/yarn.lock b/yarn.lock
index 02ac859675..67f9a959d7 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4220,6 +4220,13 @@
   dependencies:
     "@types/unist" "*"
 
+"@types/mdx-js__react@^1.5.4":
+  version "1.5.4"
+  resolved "https://registry.yarnpkg.com/@types/mdx-js__react/-/mdx-js__react-1.5.4.tgz#75ed343b5a1f56d9518e902d956e1b611da4a297"
+  integrity sha512-hce+Hymj3cEMOma13eQRhpT3mhQrOkN4CAYEwKWB/qj2BiuUrrTpCkOShEERGmLVgDc3nxF4Dc0k7W999EQxnQ==
+  dependencies:
+    "@types/react" "*"
+
 "@types/micromatch@^4.0.2":
   version "4.0.2"
   resolved "https://registry.yarnpkg.com/@types/micromatch/-/micromatch-4.0.2.tgz#ce29c8b166a73bf980a5727b1e4a4d099965151d"
@@ -4419,6 +4426,13 @@
   dependencies:
     "@types/node" "*"
 
+"@types/rtlcss@^3.1.1":
+  version "3.1.1"
+  resolved "https://registry.yarnpkg.com/@types/rtlcss/-/rtlcss-3.1.1.tgz#f091b04a2c48b92317228113a2a235c755d51c77"
+  integrity sha512-xj8SSY1sadjWrU9we6pm0jaSsZiZoZeEuzN5ebYW6SKCi6xIWLFCkKr58bHTaopqoDiyhwLbCvxIQ7uW4SK98g==
+  dependencies:
+    postcss "^8.2.x"
+
 "@types/sax@^1.2.1":
   version "1.2.1"
   resolved "https://registry.yarnpkg.com/@types/sax/-/sax-1.2.1.tgz#e0248be936ece791a82db1a57f3fb5f7c87e8172"
@@ -16035,10 +16049,10 @@ postcss-zindex@^5.0.1:
     source-map "^0.6.1"
     supports-color "^6.1.0"
 
-postcss@^8.1.7, postcss@^8.2.15, postcss@^8.2.4, postcss@^8.2.9:
-  version "8.3.1"
-  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.3.1.tgz#71f380151c227f83b898294a46481f689f86b70a"
-  integrity sha512-9qH0MGjsSm+fjxOi3GnwViL1otfi7qkj+l/WX5gcRGmZNGsIcqc+A5fBkE6PUobEQK4APqYVaES+B3Uti98TCw==
+postcss@^8.1.7, postcss@^8.2.15, postcss@^8.2.4, postcss@^8.2.9, postcss@^8.2.x:
+  version "8.3.6"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.3.6.tgz#2730dd76a97969f37f53b9a6096197be311cc4ea"
+  integrity sha512-wG1cc/JhRgdqB6WHEuyLTedf3KIRuD0hG6ldkFEZNCjRxiC+3i6kkWUUbiJQayP28iwG35cEmAbe98585BYV0A==
   dependencies:
     colorette "^1.2.2"
     nanoid "^3.1.23"