diff --git a/client/src/app/app.component.ts b/client/src/app/app.component.ts
index 17b4e0c4c..f4adef4ac 100644
--- a/client/src/app/app.component.ts
+++ b/client/src/app/app.component.ts
@@ -5,6 +5,7 @@ import { LoginDataService } from './core/services/login-data.service';
 import { ConfigService } from './core/services/config.service';
 import { ConstantsService } from './core/services/constants.service';
 import { ServertimeService } from './core/services/servertime.service';
+import { ThemeService } from './core/services/theme.service';
 
 /**
  * Angular's global App Component
@@ -25,6 +26,7 @@ export class AppComponent {
      * @param autoupdateService
      * @param notifyService
      * @param translate
+     * @param themeService used to listen to theme-changes
      */
     public constructor(
         translate: TranslateService,
@@ -32,7 +34,8 @@ export class AppComponent {
         configService: ConfigService,
         loginDataService: LoginDataService,
         constantsService: ConstantsService, // Needs to be started, so it can register itself to the WebsocketService
-        servertimeService: ServertimeService
+        servertimeService: ServertimeService,
+        themeService: ThemeService
     ) {
         // manually add the supported languages
         translate.addLangs(['en', 'de', 'cs']);
diff --git a/client/src/app/core/services/theme.service.spec.ts b/client/src/app/core/services/theme.service.spec.ts
new file mode 100644
index 000000000..51fe21708
--- /dev/null
+++ b/client/src/app/core/services/theme.service.spec.ts
@@ -0,0 +1,12 @@
+import { TestBed } from '@angular/core/testing';
+
+import { ThemeService } from './theme.service';
+
+describe('ThemeService', () => {
+    beforeEach(() => TestBed.configureTestingModule({}));
+
+    it('should be created', () => {
+        const service: ThemeService = TestBed.get(ThemeService);
+        expect(service).toBeTruthy();
+    });
+});
diff --git a/client/src/app/core/services/theme.service.ts b/client/src/app/core/services/theme.service.ts
new file mode 100644
index 000000000..c7e507996
--- /dev/null
+++ b/client/src/app/core/services/theme.service.ts
@@ -0,0 +1,31 @@
+import { Injectable } from '@angular/core';
+import { ConfigService } from './config.service';
+
+/**
+ * Service to set the theme for the OpenSlides.
+ * Reads related data from server,
+ * the server sends the value of the new theme --> the new theme has only to be added to the body.
+ */
+@Injectable({
+    providedIn: 'root'
+})
+export class ThemeService {
+    /**
+     * Here it will subscribe to the observer from config-service to read data.
+     *
+     * @param configService must be injected to get the data from server.
+     */
+    public constructor(configService: ConfigService) {
+        configService.get('openslides_theme').subscribe(newTheme => {
+            // Listen to the related event.
+            const classList = document.getElementsByTagName('body')[0].classList; // Get the classlist of the body.
+            if (newTheme) {
+                const toRemove = Array.from(classList).filter((item: string) => item.includes('theme'));
+                if (toRemove.length) {
+                    classList.remove(...toRemove); // Remove all old themes.
+                }
+                classList.add(newTheme); // Add the new theme.
+            }
+        });
+    }
+}
diff --git a/client/src/app/shared/components/logo/logo.component.ts b/client/src/app/shared/components/logo/logo.component.ts
index 92285586d..77473f0b6 100644
--- a/client/src/app/shared/components/logo/logo.component.ts
+++ b/client/src/app/shared/components/logo/logo.component.ts
@@ -1,5 +1,6 @@
 import { Component, OnInit, Input } from '@angular/core';
 import { MediaManageService } from '../../../site/mediafiles/services/media-manage.service';
+import { ConfigService } from 'app/core/services/config.service';
 
 /**
  * Reusable Logo component for Apps.
@@ -37,10 +38,15 @@ import { MediaManageService } from '../../../site/mediafiles/services/media-mana
 })
 export class LogoComponent implements OnInit {
     /**
-     * Constant path of the dark logo
+     * Constant path of the logo with dark colors for bright themes
      */
     public static STANDARD_LOGO = '/assets/img/openslides-logo-h.svg';
 
+    /**
+     * Constant path of the logo with white colors for dark themes
+     */
+    public static STANDARD_LOGO_DARK_THEME = '/assets/img/openslides-logo-h-dark-transparent.svg';
+
     /**
      * Holds the actions for logos. Updated via an observable
      */
@@ -65,11 +71,12 @@ export class LogoComponent implements OnInit {
     @Input()
     public alignment = 'center';
     /**
-     * The consotructor
+     * The constructor
      *
      * @param mmservice The Media Manage Service
+     * @param configService The ConfigService to subscribe to theme-changes
      */
-    public constructor(private mmservice: MediaManageService) {}
+    public constructor(private mmservice: MediaManageService, private configService: ConfigService) {}
 
     /**
      * Initialization function
@@ -96,6 +103,21 @@ export class LogoComponent implements OnInit {
         }
     }
 
+    /**
+     * Check if the user uses a dark theme or a 'bright' theme.
+     * In relation to the theme this will return the corresponding imagepath.
+     *
+     * @returns path of the image corresponding to the chosen theme.
+     */
+    protected getImagePathRelatedToTheme(): string {
+        const theme = this.configService.instant<string>('openslides_theme');
+        if (theme) {
+            return theme.includes('dark') ? LogoComponent.STANDARD_LOGO_DARK_THEME : LogoComponent.STANDARD_LOGO;
+        } else {
+            return LogoComponent.STANDARD_LOGO;
+        }
+    }
+
     /**
      * gets the header image based on logo action
      *
@@ -119,7 +141,7 @@ export class LogoComponent implements OnInit {
             }
         }
         if (path === '') {
-            path = LogoComponent.STANDARD_LOGO;
+            path = this.getImagePathRelatedToTheme();
         }
         return path;
     }
@@ -146,10 +168,14 @@ export class LogoComponent implements OnInit {
      *  logo was set
      */
     protected getFooterImage(logoAction: string): string {
-        if (this.getHeaderImage(logoAction) === LogoComponent.STANDARD_LOGO || this.getHeaderImage(logoAction) === '') {
+        if (
+            this.getHeaderImage(logoAction) === LogoComponent.STANDARD_LOGO ||
+            this.getHeaderImage(logoAction) === LogoComponent.STANDARD_LOGO_DARK_THEME ||
+            this.getHeaderImage(logoAction) === ''
+        ) {
             return '';
         } else {
-            return LogoComponent.STANDARD_LOGO;
+            return this.getImagePathRelatedToTheme();
         }
     }
 }
diff --git a/client/src/app/site/site.component.scss-theme.scss b/client/src/app/site/site.component.scss-theme.scss
index 3d79bc4f9..9140e26f4 100644
--- a/client/src/app/site/site.component.scss-theme.scss
+++ b/client/src/app/site/site.component.scss-theme.scss
@@ -11,7 +11,7 @@
     os-site {
         /* main background color */
         .main-container {
-            background-color: $os-background;
+            background-color: mat-color($background, background);
         }
         .nav-toolbar {
             background-color: mat-color($background, card); //TODO
@@ -37,10 +37,10 @@
         /** style the active link */
         .active {
             mat-icon {
-                color: $os-primary;
+                color: mat-color($primary);
             }
             span {
-                color: $os-primary;
+                color: mat-color($primary);
             }
         }
     }
diff --git a/client/src/assets/styles/global-components-style.scss b/client/src/assets/styles/global-components-style.scss
new file mode 100644
index 000000000..dd0245fa3
--- /dev/null
+++ b/client/src/assets/styles/global-components-style.scss
@@ -0,0 +1,34 @@
+// Material theming import
+@import '~@angular/material/theming';
+
+/**
+ *  Mixin-style to style global classes and tags with theme-related colors.
+ */
+@mixin os-components-style($theme) {
+    $primary: map-get($theme, primary);
+    $accent: map-get($theme, accent);
+    $warn: map-get($theme, warn);
+    $foreground: map-get($theme, foreground);
+    $background: map-get($theme, background);
+
+    h1, h3.accent {
+        color: mat-color($primary);
+    }
+
+    a {
+        color: mat-color($primary);
+    }
+
+    .accent-text {
+        color: mat-color($accent);
+    }
+
+    .button24 {
+        color: mat-color($primary);
+    }
+
+    //custom table header for search button, filtering and more. Used in ListViews
+    .custom-table-header {
+        background: mat-color($background, background);
+    }
+}
diff --git a/client/src/assets/styles/openslides-dark-theme.scss b/client/src/assets/styles/openslides-dark-theme.scss
new file mode 100644
index 000000000..2cdf28e8e
--- /dev/null
+++ b/client/src/assets/styles/openslides-dark-theme.scss
@@ -0,0 +1,9 @@
+$openslides-primary: mat-palette($mat-light-blue, 500, 100, 700);
+$openslides-accent: mat-palette($mat-orange, 700, 300, 900);
+$openslides-warn: mat-palette($mat-red, 600, 500, 700);
+
+$openslides-dark-theme: mat-dark-theme(
+    $openslides-primary,
+    $openslides-accent,
+    $openslides-warn
+);
diff --git a/client/src/assets/styles/openslides-green-theme.scss b/client/src/assets/styles/openslides-green-theme.scss
new file mode 100644
index 000000000..456d9c13e
--- /dev/null
+++ b/client/src/assets/styles/openslides-green-theme.scss
@@ -0,0 +1,42 @@
+$openslides-green: (
+    50: #e9f2e6,
+    100: #c8e0bf,
+    200: #a3cb95,
+    300: #7eb66b,
+    400: #62a64b,
+    500: #46962b,
+    600: #3f8e26,
+    700: #0a321e,
+    800: #092d1a,
+    900: #072616,
+    A100: #acff9d,
+    A200: #80ff6a,
+    A400: #55ff37,
+    A700: #3fff1e,
+    contrast: (
+        50: #000000,
+        100: #000000,
+        200: #000000,
+        300: #000000,
+        400: #000000,
+        500: #ffffff,
+        600: #ffffff,
+        700: #ffffff,
+        800: #ffffff,
+        900: #ffffff,
+        A100: #000000,
+        A200: #000000,
+        A400: #000000,
+        A700: #000000
+    )
+);
+
+$openslides-primary: mat-palette($openslides-green);
+$openslides-accent: mat-palette($mat-amber);
+$openslides-warn: mat-palette($mat-red);
+
+$openslides-green-theme: mat-light-theme(
+    $openslides-primary,
+    $openslides-accent,
+    $openslides-warn
+)
diff --git a/client/src/assets/styles/openslides-theme.scss b/client/src/assets/styles/openslides-theme.scss
index f7af5bf86..2952fda99 100644
--- a/client/src/assets/styles/openslides-theme.scss
+++ b/client/src/assets/styles/openslides-theme.scss
@@ -79,9 +79,22 @@ $openslides-warn: mat-palette($mat-red);
 $openslides-theme: mat-light-theme($openslides-primary, $openslides-accent, $openslides-warn);
 
 // Create Sass color vars (for using in scss files).
-$os-primary: mat-color($openslides-primary);
-$os-accent: mat-color($openslides-accent);
-$os-warn: mat-color($openslides-warn);
+// This will be set dynamically with the selecting theme
+// $os-primary: mat-color($openslides-primary);
+// $os-accent: mat-color($openslides-accent);
+// $os-warn: mat-color($openslides-warn);
 
 $os-outline: mat-color($mat-grey, 300);
 $os-background: mat-color($mat-grey, 100);
+
+/** This is the workaround to set a custom background-color
+ *  In the first step the color must be merged, in order to have to a map.
+ *  The components will get a value from this map.
+ */
+$background: map-get($openslides-theme, background);
+$background: map_merge($background, (background: $os-background));
+
+/**
+ *  Merge the theme with the custom-background.
+ */
+$openslides-theme: map_merge($openslides-theme, (background: $background));
diff --git a/client/src/index.html b/client/src/index.html
index 86e4969d0..e95a941de 100644
--- a/client/src/index.html
+++ b/client/src/index.html
@@ -12,7 +12,7 @@
     <meta name="theme-color" content="#317796">
 </head>
 
-<body>
+<body class="openslides-theme">
     <os-root></os-root>
     <noscript>Please enable JavaScript to continue using this application.</noscript>
 </body>
diff --git a/client/src/styles.scss b/client/src/styles.scss
index 2ddc0baf0..e35b5a9a3 100644
--- a/client/src/styles.scss
+++ b/client/src/styles.scss
@@ -1,23 +1,45 @@
+/** Imports the material-design-theming */
 @import '~@angular/material/theming';
 @include mat-core();
 
-/** Import brand theme and (new) component themes */
+/** Import brand theme */
 @import './assets/styles/openslides-theme.scss';
-@import './app/site/site.component.scss-theme';
+@import './assets/styles/openslides-dark-theme.scss';
+@import './assets/styles/openslides-green-theme.scss';
+
+/** Import the component-related stylesheets here */
+@import './app/site/site.component.scss-theme.scss';
+@import './assets/styles/global-components-style.scss';
 
 /** fonts */
 @import './assets/styles/fonts.scss';
 
+/** Mix the component-related style-rules */
 @mixin openslides-components-theme($theme) {
     @include os-site-theme($theme);
+    @include os-components-style($theme);
     /** More components are added here */
 }
 
-@include angular-material-theme($openslides-theme);
-@include openslides-components-theme($openslides-theme);
-
 @import '~angular-tree-component/dist/angular-tree-component.css';
 
+/** Define the classes to switch between themes */
+.openslides-theme {
+    @include angular-material-theme($openslides-theme);
+    @include openslides-components-theme($openslides-theme);
+}
+
+.openslides-dark-theme {
+    @include angular-material-theme($openslides-dark-theme);
+    @include openslides-components-theme($openslides-dark-theme);
+}
+
+.openslides-green-theme {
+    @include angular-material-theme($openslides-green-theme);
+    @include openslides-components-theme($openslides-green-theme);
+}
+
+/** Define the general style-rules */
 * {
     font-family: OSFont, Fira Sans, Roboto, Arial, Helvetica, sans-serif;
 }
@@ -30,12 +52,10 @@ mat-icon {
 }
 
 body {
-    // background: #e8eaed;
     margin: 0 auto;
     padding: 0;
     line-height: 1.5;
     font-size: 14px;
-    color: #222;
 }
 
 h1,
@@ -50,7 +70,6 @@ h3,
 h1 {
     padding-bottom: 10px;
     line-height: 1.2;
-    color: $os-primary;
     margin: 0;
     font-weight: normal;
     font-size: 36px;
@@ -59,13 +78,10 @@ h3 {
     font-weight: 500;
     margin-bottom: 0;
 }
-h3.accent {
-    color: $os-accent;
-}
+
 h4 {
     font-weight: 400;
     font-size: 12px;
-    color: rgba(0, 0, 0, 0.54);
     margin-bottom: 5px;
 
     .mat-icon-button mat-icon {
@@ -83,7 +99,6 @@ img {
 
 a {
     text-decoration: none;
-    color: #039be5; /*TODO: move to theme*/
 
     &:hover {
         text-decoration: underline;
@@ -121,9 +136,6 @@ b {
     }
 }
 
-.accent-text {
-    color: mat-color($openslides-accent);
-}
 
 .green-text {
     // TODO better name/theming
@@ -209,7 +221,6 @@ mat-card {
     height: 60px;
     line-height: 60px;
     text-align: right;
-    background: white;
     border-bottom: 1px solid rgba(0, 0, 0, 0.12);
     display: flex;
     justify-content: flex-end;
@@ -228,6 +239,7 @@ mat-card {
 
     mat-icon {
         vertical-align: text-bottom;
+        margin-right: 2px;
     }
 }
 
@@ -386,7 +398,6 @@ button.mat-menu-item.selected {
 }
 .button24 {
     background-color: white;
-    color: $os-primary !important;
     width: 24px !important;
     height: 24px !important;
 }
diff --git a/openslides/core/config_variables.py b/openslides/core/config_variables.py
index 42abf8a5b..a99143aa7 100644
--- a/openslides/core/config_variables.py
+++ b/openslides/core/config_variables.py
@@ -112,6 +112,21 @@ def get_config_variables():
         subgroup="System",
     )
 
+    yield ConfigVariable(
+        name="openslides_theme",
+        default_value="openslides-theme",
+        input_type="choice",
+        label="OpenSlides Theme",
+        choices=(
+            {"value": "openslides-theme", "display_name": "OpenSlides Default"},
+            {"value": "openslides-dark-theme", "display_name": "OpenSlides Dark"},
+            {"value": "openslides-green-theme", "display_name": "OpenSlides Green"},
+        ),
+        weight=141,
+        group="General",
+        subgroup="System",
+    )
+
     # General export settings
 
     yield ConfigVariable(