diff --git a/browser/background.js b/browser/background.js
new file mode 100644
index 00000000..1f2d5ec1
--- /dev/null
+++ b/browser/background.js
@@ -0,0 +1,32 @@
+/**
+ * @template T
+ * @param {T[]} arr
+ * @param {(v: T) => boolean} predicate
+ */
+function removeFirst(arr, predicate) {
+    const idx = arr.findIndex(predicate);
+    if (idx !== -1) arr.splice(idx, 1);
+}
+
+chrome.webRequest.onHeadersReceived.addListener(
+    ({ responseHeaders, type, url }) => {
+        if (!responseHeaders) return;
+
+        if (type === "main_frame") {
+            // In main frame requests, the CSP needs to be removed to enable fetching of custom css
+            // as desired by the user
+            removeFirst(responseHeaders, h => h.name.toLowerCase() === "content-security-policy");
+        } else if (type === "stylesheet" && url.startsWith("https://raw.githubusercontent.com/")) {
+            // Most users will load css from GitHub, but GitHub doesn't set the correct content type,
+            // so we fix it here
+            removeFirst(responseHeaders, h => h.name.toLowerCase() === "content-type");
+            responseHeaders.push({
+                name: "Content-Type",
+                value: "text/css"
+            });
+        }
+        return { responseHeaders };
+    },
+    { urls: ["https://raw.githubusercontent.com/*", "*://*.discord.com/*"], types: ["main_frame", "stylesheet"] },
+    ["blocking", "responseHeaders"]
+);
diff --git a/browser/manifestv2.json b/browser/manifestv2.json
index a6feada7..3cac9450 100644
--- a/browser/manifestv2.json
+++ b/browser/manifestv2.json
@@ -26,7 +26,11 @@
         }
     ],
 
-    "web_accessible_resources": ["dist/*", "third-party/*"],
+    "background": {
+        "scripts": ["background.js"]
+    },
+
+    "web_accessible_resources": ["dist/Vencord.js", "dist/Vencord.css"],
 
     "browser_specific_settings": {
         "gecko": {
diff --git a/scripts/build/buildWeb.mjs b/scripts/build/buildWeb.mjs
index e4eeb53e..02e4da0c 100644
--- a/scripts/build/buildWeb.mjs
+++ b/scripts/build/buildWeb.mjs
@@ -145,11 +145,11 @@ async function loadDir(dir, basePath = "") {
 /**
   * @type {(target: string, files: string[]) => Promise<void>}
  */
-async function buildExtension(target, files, noMonaco = false) {
+async function buildExtension(target, files) {
     const entries = {
         "dist/Vencord.js": await readFile("dist/extension.js"),
         "dist/Vencord.css": await readFile("dist/extension.css"),
-        ...(noMonaco ? {} : await loadDir("dist/monaco")),
+        ...await loadDir("dist/monaco"),
         ...Object.fromEntries(await Promise.all(RnNoiseFiles.map(async file =>
             [`third-party/rnnoise/${file.replace(/^dist\//, "")}`, await readFile(`node_modules/@sapphi-red/web-noise-suppressor/${file}`)]
         ))),
@@ -195,7 +195,7 @@ const appendCssRuntime = readFile("dist/Vencord.user.css", "utf-8").then(content
 await Promise.all([
     appendCssRuntime,
     buildExtension("chromium-unpacked", ["modifyResponseHeaders.json", "content.js", "manifest.json", "icon.png"]),
-    buildExtension("firefox-unpacked", ["content.js", "manifestv2.json", "icon.png"], true),
+    buildExtension("firefox-unpacked", ["background.js", "content.js", "manifestv2.json", "icon.png"]),
 ]);
 
 Zip.sync.zip("dist/chromium-unpacked").compress().save("dist/extension.zip");
diff --git a/src/components/VencordSettings/ThemesTab.tsx b/src/components/VencordSettings/ThemesTab.tsx
index 573f3b9f..f19cdcb8 100644
--- a/src/components/VencordSettings/ThemesTab.tsx
+++ b/src/components/VencordSettings/ThemesTab.tsx
@@ -18,11 +18,9 @@
 
 import { useSettings } from "@api/Settings";
 import { classNameFactory } from "@api/Styles";
-import { ErrorCard } from "@components/ErrorCard";
 import { Flex } from "@components/Flex";
 import { DeleteIcon } from "@components/Icons";
 import { Link } from "@components/Link";
-import { IsFirefox } from "@utils/constants";
 import { Margins } from "@utils/margins";
 import { classes } from "@utils/misc";
 import { showItemInFolder } from "@utils/native";
@@ -251,14 +249,12 @@ function ThemesTab() {
                             >
                                 Load missing Themes
                             </Button>
-                            {!IsFirefox && (
-                                <Button
-                                    onClick={() => VencordNative.quickCss.openEditor()}
-                                    size={Button.Sizes.SMALL}
-                                >
-                                    Edit QuickCSS
-                                </Button>
-                            )}
+                            <Button
+                                onClick={() => VencordNative.quickCss.openEditor()}
+                                size={Button.Sizes.SMALL}
+                            >
+                                Edit QuickCSS
+                            </Button>
                         </>
                     </Card>
 
@@ -320,15 +316,6 @@ function ThemesTab() {
 
     return (
         <SettingsTab title="Themes">
-            {IsFirefox && (
-                <ErrorCard>
-                    <Forms.FormTitle tag="h5">Warning</Forms.FormTitle>
-                    <Forms.FormText>
-                        You are using Firefox. Expect the vast majority of themes to not work.
-                        If this is a problem, use a chromium browser or Discord Desktop / Vesktop.
-                    </Forms.FormText>
-                </ErrorCard>
-            )}
             <TabBar
                 type="top"
                 look="brand"
diff --git a/src/components/VencordSettings/VencordTab.tsx b/src/components/VencordSettings/VencordTab.tsx
index 520e4daa..a8e9ea5b 100644
--- a/src/components/VencordSettings/VencordTab.tsx
+++ b/src/components/VencordSettings/VencordTab.tsx
@@ -21,7 +21,6 @@ import { Settings, useSettings } from "@api/Settings";
 import { classNameFactory } from "@api/Styles";
 import DonateButton from "@components/DonateButton";
 import { ErrorCard } from "@components/ErrorCard";
-import { IsFirefox } from "@utils/constants";
 import { Margins } from "@utils/margins";
 import { identity } from "@utils/misc";
 import { relaunch, showItemInFolder } from "@utils/native";
@@ -110,14 +109,12 @@ function VencordSettings() {
                                 Restart Client
                             </Button>
                         )}
-                        {!IsFirefox && (
-                            <Button
-                                onClick={() => VencordNative.quickCss.openEditor()}
-                                size={Button.Sizes.SMALL}
-                                disabled={settingsDir === "Loading..."}>
-                                Open QuickCSS File
-                            </Button>
-                        )}
+                        <Button
+                            onClick={() => VencordNative.quickCss.openEditor()}
+                            size={Button.Sizes.SMALL}
+                            disabled={settingsDir === "Loading..."}>
+                            Open QuickCSS File
+                        </Button>
                         {!IS_WEB && (
                             <Button
                                 onClick={() => showItemInFolder(settingsDir)}
diff --git a/src/plugins/_core/supportHelper.tsx b/src/plugins/_core/supportHelper.tsx
index 2e86869d..674be8e5 100644
--- a/src/plugins/_core/supportHelper.tsx
+++ b/src/plugins/_core/supportHelper.tsx
@@ -17,7 +17,7 @@
 */
 
 import { DataStore } from "@api/index";
-import { Devs, IsFirefox, SUPPORT_CHANNEL_ID } from "@utils/constants";
+import { Devs, SUPPORT_CHANNEL_ID } from "@utils/constants";
 import { isPluginDev } from "@utils/misc";
 import { makeCodeblock } from "@utils/text";
 import definePlugin from "@utils/types";
@@ -30,7 +30,6 @@ import plugins from "~plugins";
 import settings from "./settings";
 
 const REMEMBER_DISMISS_KEY = "Vencord-SupportHelper-Dismiss";
-const FIREFOX_DISMISS_KEY = "Vencord-Firefox-Warning-Dismiss";
 
 const AllowedChannelIds = [
     SUPPORT_CHANNEL_ID,
@@ -116,22 +115,6 @@ ${makeCodeblock(enabledPlugins.join(", ") + "\n\n" + enabledApiPlugins.join(", "
                     onConfirm: rememberDismiss
                 });
             }
-
-            if (IsFirefox) {
-                const rememberDismiss = () => DataStore.set(FIREFOX_DISMISS_KEY, true);
-
-                Alerts.show({
-                    title: "Hold on!",
-                    body: <div>
-                        <Forms.FormText>You are using Firefox.</Forms.FormText>
-                        <Forms.FormText>Due to Firefox's stupid extension guidelines, most themes and many plugins will not function correctly.</Forms.FormText>
-                        <Forms.FormText>Do not report bugs. Do not ask for help with broken plugins.</Forms.FormText>
-                        <Forms.FormText>Instead, use a chromium browser, Discord Desktop, or Vesktop.</Forms.FormText>
-                    </div>,
-                    onCancel: rememberDismiss,
-                    onConfirm: rememberDismiss
-                });
-            }
         }
     }
 });
diff --git a/src/utils/constants.ts b/src/utils/constants.ts
index e80298d1..6395ddfb 100644
--- a/src/utils/constants.ts
+++ b/src/utils/constants.ts
@@ -389,5 +389,3 @@ export const DevsById = /* #__PURE__*/ (() =>
             .map(([_, v]) => [v.id, v] as const)
     ))
 )() as Record<string, Dev>;
-
-export const IsFirefox = IS_EXTENSION && navigator.userAgent.toLowerCase().includes("firefox");