diff --git a/src/renderer/coremods/utilityClasses/index.ts b/src/renderer/coremods/utilityClasses/index.ts
new file mode 100644
index 000000000..6c64bf3f6
--- /dev/null
+++ b/src/renderer/coremods/utilityClasses/index.ts
@@ -0,0 +1,122 @@
+import { Injector } from "@replugged";
+import { getByProps, getByStoreName } from "src/renderer/modules/webpack";
+import { users } from "@common";
+import type React from "react";
+import type { Store } from "src/renderer/modules/common/flux";
+import type { Message } from "discord-types/general";
+
+const inject = new Injector();
+const html = document.documentElement;
+
+interface TabBarItemProps {
+  id: string;
+  "aria-controls"?: string;
+}
+
+interface TabBarItemType extends React.Component<TabBarItemProps> {
+  render(): React.ReactElement<TabBarItemProps>;
+}
+
+// Re-adds the tab bar item's ID as an always-present attribute
+function tabBarItemId(): void {
+  const TabBarModule = getByProps<{ TabBar: { Item: { prototype: TabBarItemType } } }>("TabBar");
+  if (!TabBarModule) {
+    throw new Error("Failed to find TabBar module!");
+  }
+
+  inject.after(
+    TabBarModule.TabBar.Item.prototype,
+    "render",
+    function (this: TabBarItemType, _, res) {
+      if (typeof this.props.id === "string") {
+        res.props["aria-controls"] = `${this.props.id.replace(/\s+/g, "-").toLowerCase()}-tab`;
+      }
+      return res;
+    },
+  );
+}
+
+interface ClientThemesBackgroundStore extends Store {
+  gradientPreset: { id: number } | undefined; // undefined when no nitro theme is selected
+}
+type ThemeIDMap = Record<string, number> & Record<number, string>;
+
+function onNitroThemeChange(store: ClientThemesBackgroundStore, ThemeIDMap: ThemeIDMap): void {
+  if (!store.gradientPreset) {
+    html.removeAttribute("data-nitro-theme");
+  } else {
+    const theme = ThemeIDMap[store.gradientPreset.id];
+    html.setAttribute("data-nitro-theme", theme);
+  }
+}
+
+// Adds the currently active nitro theme as a class on the html element
+function nitroThemeClass(): void {
+  const ClientThemesBackgroundStore = getByStoreName<ClientThemesBackgroundStore>(
+    "ClientThemesBackgroundStore",
+  );
+  if (!ClientThemesBackgroundStore) {
+    throw new Error("Failed to find ClientThemesBackgroundStore!");
+  }
+  const ThemeIDMap = getByProps<ThemeIDMap>("MINT_APPLE");
+  if (!ThemeIDMap) {
+    throw new Error("Failed to find ThemeIDs module!");
+  }
+
+  // update theme attribute when theme changes
+  ClientThemesBackgroundStore.addChangeListener(() => {
+    onNitroThemeChange(ClientThemesBackgroundStore, ThemeIDMap);
+  });
+  onNitroThemeChange(ClientThemesBackgroundStore, ThemeIDMap);
+}
+
+function messageDataAttributes(): void {
+  const Message = getByProps<{
+    default: { type: (msg: { message: Message }) => React.ReactElement };
+    getElementFromMessage: unknown;
+  }>("getElementFromMessage");
+
+  if (!Message) {
+    throw new Error("Failed to find Message module!");
+  }
+
+  inject.after(Message.default, "type", ([{ message }], res) => {
+    const props = res.props?.children?.props?.children?.props;
+    if (!props) return;
+    props["data-is-author-self"] = message.author.id === users.getCurrentUser().id;
+    props["data-is-author-bot"] = message.author.bot;
+    // webhooks are also considered bots
+    if (message.author.bot) {
+      props["data-is-author-webhook"] = Boolean(message.webhookId);
+    }
+    props["data-author-id"] = message.author.id;
+    props["data-message-type"] = message.type; // raw enum value, seems consistent enough to be useful
+    if (message.blocked) props["data-is-blocked"] = "true";
+    return res;
+  });
+}
+
+function addHtmlClasses(): void {
+  if (!html.classList.contains("replugged")) {
+    html.classList.add("replugged");
+  }
+}
+
+let observer: MutationObserver;
+
+export function start(): void {
+  tabBarItemId();
+  nitroThemeClass();
+  messageDataAttributes();
+
+  // generic stuff
+  observer = new MutationObserver(addHtmlClasses);
+  observer.observe(html, { attributeFilter: ["class"] });
+}
+
+export function stop(): void {
+  inject.uninjectAll();
+  observer.disconnect();
+  html.classList.remove("replugged");
+  html.removeAttribute("data-nitro-theme");
+}
diff --git a/src/renderer/managers/coremods.ts b/src/renderer/managers/coremods.ts
index cafd75fb7..d422eaaf6 100644
--- a/src/renderer/managers/coremods.ts
+++ b/src/renderer/managers/coremods.ts
@@ -34,6 +34,7 @@ export namespace coremods {
   export let watcher: Coremod;
   export let commands: Coremod;
   export let welcome: Coremod;
+  export let utilityClasses: Coremod;
 }
 
 export async function start(name: keyof typeof coremods): Promise<void> {
@@ -59,6 +60,7 @@ export async function startAll(): Promise<void> {
   coremods.watcher = await import("../coremods/watcher");
   coremods.commands = await import("../coremods/commands");
   coremods.welcome = await import("../coremods/welcome");
+  coremods.utilityClasses = await import("../coremods/utilityClasses");
 
   await Promise.all(
     Object.entries(coremods).map(async ([name, mod]) => {