diff --git a/res/css/views/auth/_AuthPage.pcss b/res/css/views/auth/_AuthPage.pcss
index 4ea4f1ffbb..e7a578b2f1 100644
--- a/res/css/views/auth/_AuthPage.pcss
+++ b/res/css/views/auth/_AuthPage.pcss
@@ -29,8 +29,13 @@ Please see LICENSE files in the repository root for full details.
         margin-top: 0;
     }
 
-    /* Apply a blurred shadow around the modal */
     &.mx_AuthPage_modal_withBlur {
+        /* Apply a blurred shadow around the modal */
         box-shadow: 0 2px 4px 0 rgb(0, 0, 0, 0.33);
+
+        .mx_AuthPage_modalContent {
+            /* Make the modal's background semitransparent */
+            background-color: $authpage-modal-content-with-blur-bg-color;
+        }
     }
 }
diff --git a/res/css/views/auth/_Welcome.pcss b/res/css/views/auth/_Welcome.pcss
index 490b6490f6..50a91aa767 100644
--- a/res/css/views/auth/_Welcome.pcss
+++ b/res/css/views/auth/_Welcome.pcss
@@ -20,3 +20,8 @@ Please see LICENSE files in the repository root for full details.
     width: 160px;
     margin-bottom: 10px;
 }
+
+/* Invert image colours in dark mode. */
+.cpd-theme-dark .mx_WelcomePage_logo {
+    filter: invert(1);
+}
diff --git a/res/themes/dark/css/_dark.pcss b/res/themes/dark/css/_dark.pcss
index c9c86717e6..326c2cd646 100644
--- a/res/themes/dark/css/_dark.pcss
+++ b/res/themes/dark/css/_dark.pcss
@@ -176,6 +176,8 @@ $togglesw-off-color: $room-highlight-color;
 /* Authpage */
 /* ******************** */
 $authpage-primary-color: $primary-content;
+/* background colour of the modal, when the background is blurred */
+$authpage-modal-content-with-blur-bg-color: rgb(0, 0, 0, 0.59);
 /* ******************** */
 
 /* Message action bar */
diff --git a/res/themes/legacy-light/css/_legacy-light.pcss b/res/themes/legacy-light/css/_legacy-light.pcss
index 7b95ded5d4..ca90eb2e55 100644
--- a/res/themes/legacy-light/css/_legacy-light.pcss
+++ b/res/themes/legacy-light/css/_legacy-light.pcss
@@ -275,6 +275,7 @@ $progressbar-bg-color: rgba(141, 151, 165, 0.2);
 
 $authpage-bg-color: #2e3649;
 $authpage-modal-bg-color: rgba(255, 255, 255, 0.59);
+$authpage-modal-content-with-blur-bg-color: rgb(255, 255, 255, 0.59);
 $authpage-focus-bg-color: #dddddd;
 $authpage-lang-color: $secondary-content;
 $authpage-primary-color: $primary-content;
diff --git a/res/themes/light/css/_light.pcss b/res/themes/light/css/_light.pcss
index 8edf5b814a..f01a85cb4c 100644
--- a/res/themes/light/css/_light.pcss
+++ b/res/themes/light/css/_light.pcss
@@ -245,6 +245,8 @@ $togglesw-ball-color: var(--cpd-color-bg-action-primary-rest);
 $authpage-primary-color: #232f32;
 $authpage-bg-color: #2e3649;
 $authpage-modal-bg-color: $roomlist-bg-color;
+/* background colour of the modal, when the background is blurred */
+$authpage-modal-content-with-blur-bg-color: rgb(255, 255, 255, 0.59);
 $authpage-focus-bg-color: $focus-bg-color;
 $authpage-lang-color: $secondary-content;
 $authpage-primary-color: $primary-content;
diff --git a/res/welcome.html b/res/welcome.html
index d2e87c3be8..f1cf3911f4 100644
--- a/res/welcome.html
+++ b/res/welcome.html
@@ -27,7 +27,6 @@
         align-items: center;
         text-align: center;
         padding: 25px 35px;
-        color: #2e2f32;
     }
 
     .mx_Logo {
diff --git a/src/components/structures/MatrixChat.tsx b/src/components/structures/MatrixChat.tsx
index b734dc9138..b0b45e4add 100644
--- a/src/components/structures/MatrixChat.tsx
+++ b/src/components/structures/MatrixChat.tsx
@@ -47,7 +47,6 @@ import PageType from "../../PageTypes";
 import createRoom, { type IOpts } from "../../createRoom";
 import { _t, _td } from "../../languageHandler";
 import SettingsStore from "../../settings/SettingsStore";
-import ThemeController from "../../settings/controllers/ThemeController";
 import { startAnyRegistrationFlow } from "../../Registration";
 import AutoDiscoveryUtils from "../../utils/AutoDiscoveryUtils";
 import { calculateRoomVia, makeRoomPermalink } from "../../utils/permalinks/Permalinks";
@@ -1016,8 +1015,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         newState.isMobileRegistration = isMobileRegistration;
 
         this.setStateForNewView(newState);
-        ThemeController.isLogin = true;
-        this.themeWatcher?.recheck();
         this.notifyNewScreen(isMobileRegistration ? "mobile_register" : "register");
     }
 
@@ -1089,8 +1086,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
                 roomJustCreatedOpts: roomInfo.justCreatedOpts,
             },
             () => {
-                ThemeController.isLogin = false;
-                this.themeWatcher?.recheck();
                 this.notifyNewScreen("room/" + presentedId, replaceLast);
             },
         );
@@ -1115,8 +1110,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             view: Views.WELCOME,
         });
         this.notifyNewScreen("welcome");
-        ThemeController.isLogin = true;
-        this.themeWatcher?.recheck();
     }
 
     private viewLogin(otherState?: any): void {
@@ -1125,8 +1118,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
             ...otherState,
         });
         this.notifyNewScreen("login");
-        ThemeController.isLogin = true;
-        this.themeWatcher?.recheck();
     }
 
     private viewHome(justRegistered = false): void {
@@ -1138,8 +1129,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         });
         this.setPage(PageType.HomePage);
         this.notifyNewScreen("home");
-        ThemeController.isLogin = false;
-        this.themeWatcher?.recheck();
     }
 
     private viewUser(userId: string, subAction: string): void {
@@ -1414,8 +1403,6 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
      * crypto is disabled.) XXX: is this a bug or a feature?
      */
     private async onLoggedIn(): Promise<void> {
-        ThemeController.isLogin = false;
-        this.themeWatcher?.recheck();
         StorageManager.tryPersistStorage();
 
         await this.onShowPostLoginScreen();
diff --git a/src/components/structures/static-page-vars.ts b/src/components/structures/static-page-vars.ts
index e27a449546..b5f21ea195 100644
--- a/src/components/structures/static-page-vars.ts
+++ b/src/components/structures/static-page-vars.ts
@@ -14,5 +14,5 @@ const matrixSvg = require("../../../res/img/matrix.svg").default;
  * Intended to replace $matrixLogo in the welcome page.
  */
 export const MATRIX_LOGO_HTML = `<a href="https://matrix.org" target="_blank" rel="noreferrer noopener">
-    <img width="79" height="34" alt="Matrix" style="padding-left: 1px;vertical-align: middle" src="${matrixSvg}"/>
+    <img class="mx_WelcomePage_logo" width="79" height="34" alt="Matrix" style="padding-left: 1px;vertical-align: middle" src="${matrixSvg}"/>
 </a>`;
diff --git a/src/components/views/auth/AuthPage.tsx b/src/components/views/auth/AuthPage.tsx
index 05da48bf2e..adc901f6c9 100644
--- a/src/components/views/auth/AuthPage.tsx
+++ b/src/components/views/auth/AuthPage.tsx
@@ -75,9 +75,8 @@ export default class AuthPage extends React.PureComponent<React.PropsWithChildre
         let modalBlur;
         if (this.props.addBlur !== false) {
             // Blur out the background: add a `div` which covers the content behind the modal,
-            // and blurs it out, and make the modal's background semitransparent.
+            // and blurs it out.
             modalBlur = <div className="mx_AuthPage_modalBlur" style={blurStyle} />;
-            modalContentStyle.background = "rgba(255, 255, 255, 0.59)";
         }
 
         const modalClasses = classNames({
diff --git a/src/settings/controllers/ThemeController.ts b/src/settings/controllers/ThemeController.ts
index 32a13ff8b7..567cc59735 100644
--- a/src/settings/controllers/ThemeController.ts
+++ b/src/settings/controllers/ThemeController.ts
@@ -12,8 +12,6 @@ import { DEFAULT_THEME, enumerateThemes } from "../../theme";
 import { type SettingLevel } from "../SettingLevel";
 
 export default class ThemeController extends SettingController {
-    public static isLogin = false;
-
     public getValueOverride(
         level: SettingLevel,
         roomId: string,
@@ -22,8 +20,6 @@ export default class ThemeController extends SettingController {
     ): any {
         if (!calculatedValue) return null; // Don't override null themes
 
-        if (ThemeController.isLogin) return "light";
-
         const themes = enumerateThemes();
         // Override in case some no longer supported theme is stored here
         if (!themes[calculatedValue]) {
diff --git a/src/settings/watchers/ThemeWatcher.ts b/src/settings/watchers/ThemeWatcher.ts
index 5ee5810884..d066e38f6f 100644
--- a/src/settings/watchers/ThemeWatcher.ts
+++ b/src/settings/watchers/ThemeWatcher.ts
@@ -13,7 +13,6 @@ import { TypedEventEmitter } from "matrix-js-sdk/src/matrix";
 import SettingsStore from "../SettingsStore";
 import dis from "../../dispatcher/dispatcher";
 import { Action } from "../../dispatcher/actions";
-import ThemeController from "../controllers/ThemeController";
 import { findHighContrastTheme } from "../../theme";
 import { type ActionPayload } from "../../dispatcher/payloads";
 import { SettingLevel } from "../SettingLevel";
@@ -88,15 +87,6 @@ export default class ThemeWatcher extends TypedEventEmitter<ThemeWatcherEvent, T
     public getEffectiveTheme(): string {
         // Dev note: Much of this logic is replicated in the AppearanceUserSettingsTab
 
-        // XXX: checking the isLight flag here makes checking it in the ThemeController
-        // itself completely redundant since we just override the result here and we're
-        // now effectively just using the ThemeController as a place to store the static
-        // variable. The system theme setting probably ought to have an equivalent
-        // controller that honours the same flag, although probably better would be to
-        // have the theme logic in one place rather than split between however many
-        // different places.
-        if (ThemeController.isLogin) return "light";
-
         // If the user has specifically enabled the system matching option (excluding default),
         // then use that over anything else. We pick the lowest possible level for the setting
         // to ensure the ordering otherwise works.
diff --git a/test/unit-tests/components/structures/__snapshots__/MatrixChat-test.tsx.snap b/test/unit-tests/components/structures/__snapshots__/MatrixChat-test.tsx.snap
index fa0c2fdf30..5aa149d284 100644
--- a/test/unit-tests/components/structures/__snapshots__/MatrixChat-test.tsx.snap
+++ b/test/unit-tests/components/structures/__snapshots__/MatrixChat-test.tsx.snap
@@ -123,7 +123,7 @@ exports[`<MatrixChat /> Multi-tab lockout waits for other tab to stop during sta
       <main
         aria-live="polite"
         class="mx_AuthPage_modalContent"
-        style="display: flex; z-index: 1; border-radius: inherit; background: rgba(255, 255, 255, 0.59);"
+        style="display: flex; z-index: 1; border-radius: inherit;"
         tabindex="-1"
       >
         <div
@@ -243,7 +243,7 @@ exports[`<MatrixChat /> with a soft-logged-out session should show the soft-logo
       <main
         aria-live="polite"
         class="mx_AuthPage_modalContent"
-        style="display: flex; z-index: 1; border-radius: inherit; background: rgba(255, 255, 255, 0.59);"
+        style="display: flex; z-index: 1; border-radius: inherit;"
         tabindex="-1"
       >
         <div
diff --git a/test/unit-tests/components/views/auth/__snapshots__/AuthPage-test.tsx.snap b/test/unit-tests/components/views/auth/__snapshots__/AuthPage-test.tsx.snap
index 67da73e0af..82579e3db7 100644
--- a/test/unit-tests/components/views/auth/__snapshots__/AuthPage-test.tsx.snap
+++ b/test/unit-tests/components/views/auth/__snapshots__/AuthPage-test.tsx.snap
@@ -16,7 +16,7 @@ exports[`<AuthPage /> should match snapshot 1`] = `
       <main
         aria-live="polite"
         class="mx_AuthPage_modalContent"
-        style="display: flex; z-index: 1; border-radius: inherit; background: rgba(255, 255, 255, 0.59);"
+        style="display: flex; z-index: 1; border-radius: inherit;"
         tabindex="-1"
       />
     </div>
diff --git a/test/unit-tests/settings/controllers/ThemeController-test.ts b/test/unit-tests/settings/controllers/ThemeController-test.ts
index c8eb607898..4cce1d85ed 100644
--- a/test/unit-tests/settings/controllers/ThemeController-test.ts
+++ b/test/unit-tests/settings/controllers/ThemeController-test.ts
@@ -14,11 +14,6 @@ import { DEFAULT_THEME } from "../../../../src/theme";
 describe("ThemeController", () => {
     jest.spyOn(SettingsStore, "getValue").mockReturnValue([]);
 
-    afterEach(() => {
-        // reset
-        ThemeController.isLogin = false;
-    });
-
     it("returns null when calculatedValue is falsy", () => {
         const controller = new ThemeController();
 
@@ -32,16 +27,6 @@ describe("ThemeController", () => {
         ).toEqual(null);
     });
 
-    it("returns light when login flag is set", () => {
-        const controller = new ThemeController();
-
-        ThemeController.isLogin = true;
-
-        expect(controller.getValueOverride(SettingLevel.ACCOUNT, "$room:server", "dark", SettingLevel.ACCOUNT)).toEqual(
-            "light",
-        );
-    });
-
     it("returns default theme when value is not a valid theme", () => {
         const controller = new ThemeController();