diff --git a/app/main.ts b/app/main.ts
index 2bed7f977db..cc0726820de 100644
--- a/app/main.ts
+++ b/app/main.ts
@@ -19,6 +19,7 @@ import {
   dialog,
   ipcMain as ipc,
   Menu,
+  nativeTheme,
   powerSaveBlocker,
   protocol as electronProtocol,
   screen,
@@ -33,8 +34,11 @@ import * as GlobalErrors from './global_errors';
 import { setup as setupCrashReports } from './crashReports';
 import { setup as setupSpellChecker } from './spell_check';
 import { redactAll, addSensitivePath } from '../ts/util/privacy';
+import { missingCaseError } from '../ts/util/missingCaseError';
 import { strictAssert } from '../ts/util/assert';
 import { consoleLogger } from '../ts/util/consoleLogger';
+import type { ThemeSettingType } from '../ts/types/Storage.d';
+import { ThemeType } from '../ts/types/Util';
 
 import './startup_config';
 
@@ -230,6 +234,61 @@ async function getSpellCheckSetting() {
   return slowValue;
 }
 
+type GetThemeSettingOptionsType = Readonly<{
+  ephemeralOnly?: boolean;
+}>;
+
+async function getThemeSetting({
+  ephemeralOnly = false,
+}: GetThemeSettingOptionsType = {}): Promise<ThemeSettingType> {
+  const fastValue = ephemeralConfig.get('theme-setting');
+  if (fastValue !== undefined) {
+    getLogger().info('got fast theme-setting value', fastValue);
+    return fastValue as ThemeSettingType;
+  }
+
+  if (ephemeralOnly) {
+    return 'system';
+  }
+
+  const json = await sql.sqlCall('getItemById', ['theme-setting']);
+
+  // Default to `system` if setting doesn't exist yet
+  const slowValue = json ? json.value : 'system';
+
+  ephemeralConfig.set('theme-setting', slowValue);
+
+  getLogger().info('got slow theme-setting value', slowValue);
+
+  return slowValue;
+}
+
+async function getResolvedThemeSetting(
+  options?: GetThemeSettingOptionsType
+): Promise<ThemeType> {
+  const theme = await getThemeSetting(options);
+  if (theme === 'system') {
+    return nativeTheme.shouldUseDarkColors ? ThemeType.dark : ThemeType.light;
+  }
+  return ThemeType[theme];
+}
+
+async function getBackgroundColor(
+  options?: GetThemeSettingOptionsType
+): Promise<string> {
+  const theme = await getResolvedThemeSetting(options);
+
+  if (theme === 'light') {
+    return '#3a76f0';
+  }
+
+  if (theme === 'dark') {
+    return '#121212';
+  }
+
+  throw missingCaseError(theme);
+}
+
 let systemTrayService: SystemTrayService | undefined;
 const systemTraySettingCache = new SystemTraySettingCache(
   sql,
@@ -479,7 +538,7 @@ async function createWindow() {
         : 'default',
     backgroundColor: isTestEnvironment(getEnvironment())
       ? '#ffffff' // Tests should always be rendered on a white background
-      : '#3a76f0',
+      : await getBackgroundColor(),
     webPreferences: {
       ...defaultWebPrefs,
       nodeIntegration: false,
@@ -599,6 +658,7 @@ async function createWindow() {
 
   const moreKeys = {
     isFullScreen: String(Boolean(mainWindow.isFullScreen())),
+    resolvedTheme: await getResolvedThemeSetting(),
   };
 
   if (getEnvironment() === Environment.Test) {
@@ -996,7 +1056,7 @@ function showScreenShareWindow(sourceName: string) {
 }
 
 let aboutWindow: BrowserWindow | undefined;
-function showAbout() {
+async function showAbout() {
   if (aboutWindow) {
     aboutWindow.show();
     return;
@@ -1008,7 +1068,7 @@ function showAbout() {
     resizable: false,
     title: getLocale().i18n('aboutSignalDesktop'),
     autoHideMenuBar: true,
-    backgroundColor: '#3a76f0',
+    backgroundColor: await getBackgroundColor(),
     show: false,
     webPreferences: {
       ...defaultWebPrefs,
@@ -1038,7 +1098,7 @@ function showAbout() {
 }
 
 let settingsWindow: BrowserWindow | undefined;
-function showSettingsWindow() {
+async function showSettingsWindow() {
   if (settingsWindow) {
     settingsWindow.show();
     return;
@@ -1051,7 +1111,7 @@ function showSettingsWindow() {
     resizable: false,
     title: getLocale().i18n('signalDesktopPreferences'),
     autoHideMenuBar: true,
-    backgroundColor: '#3a76f0',
+    backgroundColor: await getBackgroundColor(),
     show: false,
     webPreferences: {
       ...defaultWebPrefs,
@@ -1121,7 +1181,7 @@ async function showStickerCreator() {
     height: 650,
     title: getLocale().i18n('signalDesktopStickerCreator'),
     autoHideMenuBar: true,
-    backgroundColor: '#3a76f0',
+    backgroundColor: await getBackgroundColor(),
     show: false,
     webPreferences: {
       ...defaultWebPrefs,
@@ -1172,16 +1232,14 @@ async function showDebugLogWindow() {
     return;
   }
 
-  const theme = settingsChannel
-    ? await settingsChannel.getSettingFromMainWindow('themeSetting')
-    : undefined;
+  const theme = await getThemeSetting();
   const options = {
     width: 700,
     height: 500,
     resizable: false,
     title: getLocale().i18n('debugLog'),
     autoHideMenuBar: true,
-    backgroundColor: '#3a76f0',
+    backgroundColor: await getBackgroundColor(),
     show: false,
     webPreferences: {
       ...defaultWebPrefs,
@@ -1235,9 +1293,7 @@ function showPermissionsPopupWindow(forCalling: boolean, forCamera: boolean) {
       return;
     }
 
-    const theme = settingsChannel
-      ? await settingsChannel.getSettingFromMainWindow('themeSetting')
-      : undefined;
+    const theme = await getThemeSetting();
     const size = mainWindow.getSize();
     const options = {
       width: Math.min(400, size[0]),
@@ -1245,7 +1301,7 @@ function showPermissionsPopupWindow(forCalling: boolean, forCamera: boolean) {
       resizable: false,
       title: getLocale().i18n('allowAccess'),
       autoHideMenuBar: true,
-      backgroundColor: '#3a76f0',
+      backgroundColor: await getBackgroundColor(),
       show: false,
       modal: true,
       webPreferences: {
@@ -1509,6 +1565,12 @@ app.on('ready', async () => {
   const timeout = new Promise(resolveFn =>
     setTimeout(resolveFn, 3000, 'timeout')
   );
+
+  // This color is to be used only in loading screen and in this case we should
+  // never wait for the database to be initialized. Thus the theme setting
+  // lookup should be done only in ephemeral config.
+  const backgroundColor = await getBackgroundColor({ ephemeralOnly: true });
+
   // eslint-disable-next-line more/no-then
   Promise.race([sqlInitPromise, timeout]).then(maybeTimeout => {
     if (maybeTimeout !== 'timeout') {
@@ -1525,7 +1587,7 @@ app.on('ready', async () => {
       height: 265,
       resizable: false,
       frame: false,
-      backgroundColor: '#3a76f0',
+      backgroundColor,
       webPreferences: {
         ...defaultWebPrefs,
         nodeIntegration: false,
diff --git a/preload.js b/preload.js
index 6e0784aadb0..32c88d4676f 100644
--- a/preload.js
+++ b/preload.js
@@ -15,6 +15,7 @@ try {
   const { strictAssert } = require('./ts/util/assert');
   const { parseIntWithFallback } = require('./ts/util/parseIntWithFallback');
   const { UUIDKind } = require('./ts/types/UUID');
+  const { ThemeType } = require('./ts/types/Util');
 
   // It is important to call this as early as possible
   const { SignalContext } = require('./ts/windows/context');
@@ -247,6 +248,12 @@ try {
     });
   }
 
+  if (config.resolvedTheme === 'light') {
+    window.initialTheme = ThemeType.light;
+  } else if (config.resolvedTheme === 'dark') {
+    window.initialTheme = ThemeType.dark;
+  }
+
   // Settings-related events
 
   window.showSettings = () => ipc.send('show-settings');
diff --git a/stylesheets/_global.scss b/stylesheets/_global.scss
index 9665d2af017..e709364f773 100644
--- a/stylesheets/_global.scss
+++ b/stylesheets/_global.scss
@@ -235,7 +235,16 @@ $loading-height: 16px;
   right: 0;
   top: 0;
   bottom: 0;
-  background-color: $color-ultramarine-icon;
+
+  /* Note: background-color is intentionally transparent until body has the
+   *       theme class.
+   */
+  @include explicit-light-theme {
+    background-color: $color-ultramarine-icon;
+  }
+  @include dark-theme {
+    background-color: $color-gray-95;
+  }
   color: $color-white;
   display: flex;
   flex-direction: column;
diff --git a/stylesheets/_mixins.scss b/stylesheets/_mixins.scss
index 16af1688898..5a87e596003 100644
--- a/stylesheets/_mixins.scss
+++ b/stylesheets/_mixins.scss
@@ -97,6 +97,12 @@
   @content;
 }
 
+@mixin explicit-light-theme() {
+  .light-theme & {
+    @content;
+  }
+}
+
 @mixin dark-theme() {
   .dark-theme & {
     @content;
diff --git a/ts/background.ts b/ts/background.ts
index 95979424203..d81ec041ad9 100644
--- a/ts/background.ts
+++ b/ts/background.ts
@@ -29,6 +29,7 @@ import type { Receipt } from './types/Receipt';
 import { getTitleBarVisibility, TitleBarVisibility } from './types/Settings';
 import { SocketStatus } from './types/SocketStatus';
 import { DEFAULT_CONVERSATION_COLOR } from './types/Colors';
+import { ThemeType } from './types/Util';
 import { ChallengeHandler } from './challenge';
 import * as durations from './util/durations';
 import { explodePromise } from './util/explodePromise';
@@ -166,6 +167,13 @@ export async function cleanupSessionResets(): Promise<void> {
 }
 
 export async function startApp(): Promise<void> {
+  if (window.initialTheme === ThemeType.light) {
+    document.body.classList.add('light-theme');
+  }
+  if (window.initialTheme === ThemeType.dark) {
+    document.body.classList.add('dark-theme');
+  }
+
   const idleDetector = new IdleDetector();
 
   await KeyboardLayout.initialize();
diff --git a/ts/main/settingsChannel.ts b/ts/main/settingsChannel.ts
index e9cc1bffba5..bb06746f52b 100644
--- a/ts/main/settingsChannel.ts
+++ b/ts/main/settingsChannel.ts
@@ -17,6 +17,7 @@ import type {
 const EPHEMERAL_NAME_MAP = new Map([
   ['spellCheck', 'spell-check'],
   ['systemTraySetting', 'system-tray-setting'],
+  ['themeSetting', 'theme-setting'],
 ]);
 
 type ResponseQueueEntry = Readonly<{
@@ -68,7 +69,9 @@ export class SettingsChannel {
     this.installSetting('readReceiptSetting', { setter: false });
     this.installSetting('typingIndicatorSetting', { setter: false });
 
-    this.installSetting('themeSetting');
+    this.installSetting('themeSetting', {
+      isEphemeral: true,
+    });
     this.installSetting('hideMenuBar');
     this.installSetting('systemTraySetting', {
       isEphemeral: true,
diff --git a/ts/window.d.ts b/ts/window.d.ts
index 874acc50169..abf6e4e14a9 100644
--- a/ts/window.d.ts
+++ b/ts/window.d.ts
@@ -29,7 +29,7 @@ import * as Curve from './Curve';
 import * as RemoteConfig from './RemoteConfig';
 import * as OS from './OS';
 import { getEnvironment } from './environment';
-import { LocalizerType } from './types/Util';
+import { LocalizerType, ThemeType } from './types/Util';
 import type { Receipt } from './types/Receipt';
 import { ConversationController } from './ConversationController';
 import { ReduxActions } from './state/types';
@@ -212,6 +212,7 @@ declare global {
     isAfterVersion: (version: string, anotherVersion: string) => boolean;
     isBeforeVersion: (version: string, anotherVersion: string) => boolean;
     isFullScreen: () => boolean;
+    initialTheme?: ThemeType;
     libphonenumber: {
       util: {
         getRegionCodeForNumber: (number: string) => string;