diff --git a/CHANGELOG.md b/CHANGELOG.md
index b9880d0d..1c39495e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 * [#379](https://github.com/shlinkio/shlink-web-client/issues/379) and [#384](https://github.com/shlinkio/shlink-web-client/issues/384) Improved QR code modal, including controls to customize size, format and margin, as well as a button to copy the link to the clipboard.
 * [#385](https://github.com/shlinkio/shlink-web-client/issues/385) Added setting to determine if "validate URL" should be enabled or disabled by default.
 * [#386](https://github.com/shlinkio/shlink-web-client/issues/386) Added new card in overview section to display amount of orphan visits when using Shlink 2.6.0 or higher.
+* [#177](https://github.com/shlinkio/shlink-web-client/issues/177) Added dark theme.
 
 ### Changed
 * *Nothing*
diff --git a/src/App.tsx b/src/App.tsx
index 4928f42d..23938617 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -2,11 +2,14 @@ import { useEffect, FC } from 'react';
 import { Route, Switch } from 'react-router-dom';
 import NotFound from './common/NotFound';
 import { ServersMap } from './servers/data';
+import { Settings } from './settings/reducers/settings';
+import { changeThemeInMarkup } from './utils/theme';
 import './App.scss';
 
 interface AppProps {
   fetchServers: Function;
   servers: ServersMap;
+  settings: Settings;
 }
 
 const App = (
@@ -17,12 +20,14 @@ const App = (
   EditServer: FC,
   Settings: FC,
   ShlinkVersionsContainer: FC,
-) => ({ fetchServers, servers }: AppProps) => {
-  // On first load, try to fetch the remote servers if the list is empty
+) => ({ fetchServers, servers, settings }: AppProps) => {
   useEffect(() => {
+    // On first load, try to fetch the remote servers if the list is empty
     if (Object.keys(servers).length === 0) {
       fetchServers();
     }
+
+    changeThemeInMarkup(settings.ui?.theme ?? 'light');
   }, []);
 
   return (
diff --git a/src/common/AsideMenu.scss b/src/common/AsideMenu.scss
index 09e0dc3e..35b0339e 100644
--- a/src/common/AsideMenu.scss
+++ b/src/common/AsideMenu.scss
@@ -3,7 +3,7 @@
 
 .aside-menu {
   width: $asideMenuWidth;
-  background-color: white;
+  background-color: var(--primary-color);
   box-shadow: rgba(0, 0, 0, .05) 0 8px 15px;
   position: fixed !important;
   padding-top: 13px;
@@ -18,7 +18,6 @@
 
   @media (min-width: $mdMin) {
     padding: 30px 15px 15px;
-    border-right: 1px solid #eeeeee;
   }
 
   @media (max-width: $smMax) {
@@ -50,17 +49,13 @@
 }
 
 .aside-menu__item:hover {
-  background-color: $lightColor;
-}
-
-.aside-menu__item--selected {
-  color: #ffffff;
-  background-color: $mainColor;
+  background-color: var(--secondary-color);
 }
 
+.aside-menu__item--selected,
 .aside-menu__item--selected:hover {
   color: #ffffff;
-  background-color: $mainColor;
+  background-color: var(--brand-color);
 }
 
 .aside-menu__item--divider {
diff --git a/src/common/Home.scss b/src/common/Home.scss
index 775de88f..c8a00d35 100644
--- a/src/common/Home.scss
+++ b/src/common/Home.scss
@@ -36,6 +36,6 @@
 
 .home__servers-container {
   @media (min-width: $mdMin) {
-    border-left: 1px solid rgba(0, 0, 0, .125);
+    border-left: 1px solid var(--border-color);
   }
 }
diff --git a/src/common/MainHeader.scss b/src/common/MainHeader.scss
index 89279c68..03d9ce80 100644
--- a/src/common/MainHeader.scss
+++ b/src/common/MainHeader.scss
@@ -1,8 +1,8 @@
 @import '../utils/base';
 
 .main-header.main-header {
-  background-color: $mainColor !important;
   color: white;
+  background-color: var(--brand-color) !important;
 
   .navbar-brand {
     color: inherit !important;
diff --git a/src/common/react-tagsinput.scss b/src/common/react-tagsinput.scss
index 6753a0f9..6ecd1cd3 100644
--- a/src/common/react-tagsinput.scss
+++ b/src/common/react-tagsinput.scss
@@ -1,6 +1,8 @@
+@import '../utils/base';
+
 .react-tagsinput {
-  background-color: #ffffff;
-  border: 1px solid #cccccc;
+  background-color: var(--input-color);
+  border: 1px solid var(--input-border-color);
   border-radius: .25rem;
   overflow: hidden;
   min-height: 2.6rem;
@@ -10,7 +12,7 @@
 
 .react-tagsinput--focused {
   border-color: #80bdff;
-  box-shadow: 0 0 0 .2rem rgba(0, 123, 255, .25);
+  box-shadow: 0 0 0 .2rem rgb(70 150 229 / 25%);
 }
 
 .react-tagsinput-tag {
@@ -44,5 +46,13 @@
   width: 100%;
   margin-bottom: 6px;
   font-size: 1.25rem;
-  color: #495057;
+  color: var(--input-text-color);
+}
+
+.react-tagsinput-input::placeholder {
+  color: $textPlaceholder;
+}
+
+.react-autosuggest__suggestion--highlighted {
+  background-color: var(--active-color);
 }
diff --git a/src/container/index.ts b/src/container/index.ts
index f7a0d3cf..b369c1f8 100644
--- a/src/container/index.ts
+++ b/src/container/index.ts
@@ -43,7 +43,7 @@ bottle.serviceFactory(
   'Settings',
   'ShlinkVersionsContainer',
 );
-bottle.decorator('App', connect([ 'servers' ], [ 'fetchServers' ]));
+bottle.decorator('App', connect([ 'servers', 'settings' ], [ 'fetchServers' ]));
 
 provideCommonServices(bottle, connect, withRouter);
 provideApiServices(bottle);
diff --git a/src/domains/DomainSelector.scss b/src/domains/DomainSelector.scss
index 89e02433..729f58ea 100644
--- a/src/domains/DomainSelector.scss
+++ b/src/domains/DomainSelector.scss
@@ -1,12 +1,19 @@
+@import '../utils/base';
 @import '../utils/mixins/vertical-align';
 
+.domains-dropdown__toggle-btn.domains-dropdown__toggle-btn,
+.domains-dropdown__toggle-btn.domains-dropdown__toggle-btn:hover,
+.domains-dropdown__toggle-btn.domains-dropdown__toggle-btn:active {
+  color: $textPlaceholder !important;
+}
+
 .domains-dropdown__toggle-btn--active.domains-dropdown__toggle-btn--active,
 .domains-dropdown__toggle-btn--active.domains-dropdown__toggle-btn--active:hover,
 .domains-dropdown__toggle-btn--active.domains-dropdown__toggle-btn--active:active {
-  color: #495057 !important;
+  color: var(--input-text-color) !important;
 }
 
 .domains-dropdown__back-btn.domains-dropdown__back-btn,
 .domains-dropdown__back-btn.domains-dropdown__back-btn:hover {
-  border-color: #ced4da;
+  border-color: var(--border-color);
 }
diff --git a/src/domains/DomainSelector.tsx b/src/domains/DomainSelector.tsx
index c843f409..5ab1e591 100644
--- a/src/domains/DomainSelector.tsx
+++ b/src/domains/DomainSelector.tsx
@@ -54,7 +54,7 @@ export const DomainSelector = ({ listDomains, value, domainsList, onChange }: Do
   ) : (
     <DropdownBtn
       text={valueIsEmpty ? 'Domain' : `Domain: ${value}`}
-      className={!valueIsEmpty ? 'domains-dropdown__toggle-btn--active' : ''}
+      className={!valueIsEmpty ? 'domains-dropdown__toggle-btn--active' : 'domains-dropdown__toggle-btn'}
     >
       {domains.map(({ domain, isDefault }) => (
         <DropdownItem
diff --git a/src/index.scss b/src/index.scss
index d5542c25..65ebc4f1 100644
--- a/src/index.scss
+++ b/src/index.scss
@@ -1,32 +1,87 @@
+/* stylelint-disable no-descending-specificity */
+
 @import './utils/base';
 @import 'node_modules/bootstrap/scss/bootstrap.scss';
 @import './common/react-tagsinput.scss';
+@import './theme/theme';
+
+* {
+  outline: none !important;
+}
 
 html,
 body,
 #root {
   height: 100%;
-  background: $lightColor;
-}
-
-* {
-  outline: none !important;
+  background: var(--secondary-color);
+  color: var(--text-color);
 }
 
 .bg-main {
   background-color: $mainColor !important;
 }
 
-.card {
-  box-shadow: 0 .125rem .25rem rgba(0, 0, 0, .075);
-}
-
-.card-header {
-  background-color: white;
+.card-body,
+.card-header,
+.list-group-item {
+  background-color: transparent;
 }
 
 .card-footer {
-  background-color: rgba(255, 255, 255, .5);
+  background-color: var(--primary-color-alfa);
+}
+
+.card {
+  box-shadow: 0 .125rem .25rem rgba(0, 0, 0, .075);
+  background-color: var(--primary-color);
+  border-color: var(--border-color);
+}
+
+.list-group {
+  background-color: var(--primary-color);
+}
+
+.modal-content,
+.page-link,
+.page-item.disabled .page-link,
+.dropdown-menu {
+  background-color: var(--primary-color);
+}
+
+.modal-header,
+.modal-footer,
+.card-header,
+.card-footer,
+.table thead th,
+.table th,
+.table td,
+.page-link,
+.page-link:hover,
+.page-item.disabled .page-link,
+.dropdown-divider,
+.dropdown-menu,
+.list-group-item,
+.modal-content {
+  border-color: var(--border-color);
+}
+
+.table-bordered,
+.table-bordered thead th,
+.table-bordered thead td {
+  border-color: var(--table-border-color);
+}
+
+.page-link:hover {
+  background-color: var(--secondary-color);
+}
+
+.page-item.active .page-link {
+  background-color: var(--brand-color);
+  border-color: var(--brand-color);
+}
+
+.pagination .page-link {
+  cursor: pointer;
 }
 
 .container-xl {
@@ -40,32 +95,61 @@ body,
   }
 }
 
+.dropdown-item,
+.dropdown-item-text {
+  color: var(--text-color);
+}
+
 .dropdown-item:not(:disabled) {
   cursor: pointer;
 }
 
+.dropdown-item:focus:not(:disabled),
+.dropdown-item:hover:not(:disabled),
 .dropdown-item.active:not(:disabled),
 .dropdown-item:active:not(:disabled) {
-  background-color: $lightGrey !important;
-  color: inherit !important;
+  background-color: var(--active-color) !important;
+  color: var(--text-color) !important;
 }
 
 .badge-main {
   color: #ffffff;
-  background-color: $mainColor;
+  background-color: var(--brand-color);
+}
+
+.close,
+.close:hover,
+.table,
+.table-hover tbody tr:hover {
+  color: var(--text-color);
 }
 
 .table-hover tbody tr:hover {
-  background-color: $lightColor;
+  background-color: var(--secondary-color);
 }
 
-.react-datepicker__input-container,
-.react-datepicker-wrapper {
-  display: block !important;
+.form-control,
+.form-control:focus {
+  background-color: var(--primary-color);
+  border-color: var(--input-border-color);
+  color: var(--input-text-color);
 }
 
-.react-datepicker-popper {
-  z-index: 2;
+.form-control.disabled,
+.form-control:disabled {
+  background-color: var(--input-disabled-color);
+  cursor: not-allowed;
+}
+
+.card .form-control:not(:disabled),
+.card .form-control:not(:disabled):hover {
+  background-color: var(--input-color);
+}
+
+.table-active,
+.table-active > th,
+.table-active > td {
+  background-color: var(--table-highlight-color) !important;
 }
 
 .navbar-brand {
@@ -74,10 +158,6 @@ body,
   }
 }
 
-.pagination .page-link {
-  cursor: pointer;
-}
-
 .indivisible {
   white-space: nowrap;
 }
@@ -92,14 +172,6 @@ body,
   white-space: nowrap;
 }
 
-.react-datepicker__day--keyboard-selected {
-  background-color: $mainColor;
-
-  &:hover {
-    background-color: darken($mainColor, 12%);
-  }
-}
-
 .progress-bar {
   background-color: $mainColor;
 }
diff --git a/src/servers/Overview.scss b/src/servers/Overview.scss
index 75a56ec4..f8b49ad7 100644
--- a/src/servers/Overview.scss
+++ b/src/servers/Overview.scss
@@ -2,10 +2,10 @@
 
 .overview__card.overview__card {
   text-align: center;
-  border-top: 3px solid $mainColor;
+  border-top: 3px solid var(--brand-color);
 }
 
 .overview__card-title {
   text-transform: uppercase;
-  color: #6c757d;
+  color: $textPlaceholder;
 }
diff --git a/src/servers/ServersListGroup.scss b/src/servers/ServersListGroup.scss
index 78457102..9a0709f0 100644
--- a/src/servers/ServersListGroup.scss
+++ b/src/servers/ServersListGroup.scss
@@ -18,7 +18,7 @@
 }
 
 .servers-list__server-item:hover {
-  background-color: $lightColor;
+  background-color: var(--secondary-color);
 }
 
 .servers-list__server-item-icon {
@@ -29,7 +29,7 @@
 
 .servers-list__list-group--embedded.servers-list__list-group--embedded {
   border-radius: 0;
-  border-top: 1px solid rgba(0, 0, 0, .125);
+  border-top: 1px solid var(--border-color);
 
   @media (min-width: $mdMin) {
     max-height: 220px;
@@ -40,6 +40,6 @@
 
   .servers-list__server-item {
     border: none;
-    border-bottom: 1px solid rgba(0, 0, 0, .125);
+    border-bottom: 1px solid var(--border-color);
   }
 }
diff --git a/src/settings/RealTimeUpdates.tsx b/src/settings/RealTimeUpdates.tsx
index 914c5a6f..d737f6e9 100644
--- a/src/settings/RealTimeUpdates.tsx
+++ b/src/settings/RealTimeUpdates.tsx
@@ -19,6 +19,9 @@ const RealTimeUpdates = (
     <FormGroup>
       <ToggleSwitch checked={realTimeUpdates.enabled} onChange={toggleRealTimeUpdates}>
         Enable or disable real-time updates, when using Shlink v2.2.0 or newer.
+        <small className="form-text text-muted">
+          Real-time updates are currently being <b>{realTimeUpdates.enabled ? 'processed' : 'ignored'}</b>.
+        </small>
       </ToggleSwitch>
     </FormGroup>
     <FormGroup className="mb-0">
diff --git a/src/settings/Settings.tsx b/src/settings/Settings.tsx
index bbd524d9..8e6731f5 100644
--- a/src/settings/Settings.tsx
+++ b/src/settings/Settings.tsx
@@ -2,14 +2,19 @@ import { FC } from 'react';
 import { Row } from 'reactstrap';
 import NoMenuLayout from '../common/NoMenuLayout';
 
-const Settings = (RealTimeUpdates: FC, ShortUrlCreation: FC) => () => (
+const Settings = (RealTimeUpdates: FC, ShortUrlCreation: FC, UserInterface: FC) => () => (
   <NoMenuLayout>
     <Row>
       <div className="col-lg-6">
-        <RealTimeUpdates />
+        <div className="mb-3 mb-md-4">
+          <UserInterface />
+        </div>
+        <div className="mb-3 mb-md-4">
+          <ShortUrlCreation />
+        </div>
       </div>
       <div className="col-lg-6">
-        <ShortUrlCreation />
+        <RealTimeUpdates />
       </div>
     </Row>
   </NoMenuLayout>
diff --git a/src/settings/UserInterface.scss b/src/settings/UserInterface.scss
new file mode 100644
index 00000000..121b0784
--- /dev/null
+++ b/src/settings/UserInterface.scss
@@ -0,0 +1,4 @@
+.user-interface__theme-icon {
+  float: right;
+  margin-top: .25rem;
+}
diff --git a/src/settings/UserInterface.tsx b/src/settings/UserInterface.tsx
new file mode 100644
index 00000000..3180ebc4
--- /dev/null
+++ b/src/settings/UserInterface.tsx
@@ -0,0 +1,30 @@
+import { FC } from 'react';
+import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
+import { faSun, faMoon } from '@fortawesome/free-solid-svg-icons';
+import { SimpleCard } from '../utils/SimpleCard';
+import ToggleSwitch from '../utils/ToggleSwitch';
+import { changeThemeInMarkup, Theme } from '../utils/theme';
+import { Settings, UiSettings } from './reducers/settings';
+import './UserInterface.scss';
+
+interface UserInterfaceProps {
+  settings: Settings;
+  setUiSettings: (settings: UiSettings) => void;
+}
+
+export const UserInterface: FC<UserInterfaceProps> = ({ settings: { ui }, setUiSettings }) => (
+  <SimpleCard title="User interface">
+    <FontAwesomeIcon icon={ui?.theme === 'dark' ? faMoon : faSun} className="user-interface__theme-icon" />
+    <ToggleSwitch
+      checked={ui?.theme === 'dark'}
+      onChange={(useDarkTheme) => {
+        const theme: Theme = useDarkTheme ? 'dark' : 'light';
+
+        setUiSettings({ theme });
+        changeThemeInMarkup(theme);
+      }}
+    >
+      Use dark theme.
+    </ToggleSwitch>
+  </SimpleCard>
+);
diff --git a/src/settings/reducers/settings.ts b/src/settings/reducers/settings.ts
index aa1bc929..e5c0d1f9 100644
--- a/src/settings/reducers/settings.ts
+++ b/src/settings/reducers/settings.ts
@@ -2,6 +2,7 @@ import { Action } from 'redux';
 import { dissoc, mergeDeepRight } from 'ramda';
 import { buildReducer } from '../../utils/helpers/redux';
 import { RecursivePartial } from '../../utils/utils';
+import { Theme } from '../../utils/theme';
 
 export const SET_SETTINGS = 'shlink/realTimeUpdates/SET_SETTINGS';
 
@@ -19,9 +20,14 @@ export interface ShortUrlCreationSettings {
   validateUrls: boolean;
 }
 
+export interface UiSettings {
+  theme: Theme;
+}
+
 export interface Settings {
   realTimeUpdates: RealTimeUpdatesSettings;
   shortUrlCreation?: ShortUrlCreationSettings;
+  ui?: UiSettings;
 }
 
 const initialState: Settings = {
@@ -31,6 +37,9 @@ const initialState: Settings = {
   shortUrlCreation: {
     validateUrls: false,
   },
+  ui: {
+    theme: 'light',
+  },
 };
 
 type SettingsAction = Action & Settings;
@@ -55,3 +64,8 @@ export const setShortUrlCreationSettings = (settings: ShortUrlCreationSettings):
   type: SET_SETTINGS,
   shortUrlCreation: settings,
 });
+
+export const setUiSettings = (settings: UiSettings): PartialSettingsAction => ({
+  type: SET_SETTINGS,
+  ui: settings,
+});
diff --git a/src/settings/services/provideServices.ts b/src/settings/services/provideServices.ts
index 393ccefc..cd01599b 100644
--- a/src/settings/services/provideServices.ts
+++ b/src/settings/services/provideServices.ts
@@ -1,14 +1,20 @@
 import Bottle from 'bottlejs';
 import RealTimeUpdates from '../RealTimeUpdates';
 import Settings from '../Settings';
-import { setRealTimeUpdatesInterval, setShortUrlCreationSettings, toggleRealTimeUpdates } from '../reducers/settings';
+import {
+  setRealTimeUpdatesInterval,
+  setShortUrlCreationSettings,
+  setUiSettings,
+  toggleRealTimeUpdates,
+} from '../reducers/settings';
 import { ConnectDecorator } from '../../container/types';
 import { withoutSelectedServer } from '../../servers/helpers/withoutSelectedServer';
 import { ShortUrlCreation } from '../ShortUrlCreation';
+import { UserInterface } from '../UserInterface';
 
 const provideServices = (bottle: Bottle, connect: ConnectDecorator) => {
   // Components
-  bottle.serviceFactory('Settings', Settings, 'RealTimeUpdates', 'ShortUrlCreation');
+  bottle.serviceFactory('Settings', Settings, 'RealTimeUpdates', 'ShortUrlCreation', 'UserInterface');
   bottle.decorator('Settings', withoutSelectedServer);
   bottle.decorator('Settings', connect(null, [ 'resetSelectedServer' ]));
 
@@ -21,10 +27,14 @@ const provideServices = (bottle: Bottle, connect: ConnectDecorator) => {
   bottle.serviceFactory('ShortUrlCreation', () => ShortUrlCreation);
   bottle.decorator('ShortUrlCreation', connect([ 'settings' ], [ 'setShortUrlCreationSettings' ]));
 
+  bottle.serviceFactory('UserInterface', () => UserInterface);
+  bottle.decorator('UserInterface', connect([ 'settings' ], [ 'setUiSettings' ]));
+
   // Actions
   bottle.serviceFactory('toggleRealTimeUpdates', () => toggleRealTimeUpdates);
   bottle.serviceFactory('setRealTimeUpdatesInterval', () => setRealTimeUpdatesInterval);
   bottle.serviceFactory('setShortUrlCreationSettings', () => setShortUrlCreationSettings);
+  bottle.serviceFactory('setUiSettings', () => setUiSettings);
 };
 
 export default provideServices;
diff --git a/src/short-urls/Paginator.scss b/src/short-urls/Paginator.scss
index 03b784d0..b28b471a 100644
--- a/src/short-urls/Paginator.scss
+++ b/src/short-urls/Paginator.scss
@@ -1,7 +1,7 @@
 .short-urls-paginator {
   position: sticky;
   bottom: 0;
-  background-color: rgba(255, 255, 255, .5);
+  background-color: var(--primary-color-alfa);
   padding: .75rem 0;
-  border-top: 1px solid rgba(black, .125);
+  border-top: 1px solid var(--border-color);
 }
diff --git a/src/short-urls/UseExistingIfFoundInfoIcon.tsx b/src/short-urls/UseExistingIfFoundInfoIcon.tsx
index c737d690..2d003a1e 100644
--- a/src/short-urls/UseExistingIfFoundInfoIcon.tsx
+++ b/src/short-urls/UseExistingIfFoundInfoIcon.tsx
@@ -1,8 +1,8 @@
 import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
 import { faInfoCircle as infoIcon } from '@fortawesome/free-solid-svg-icons';
 import { Modal, ModalBody, ModalHeader } from 'reactstrap';
-import './UseExistingIfFoundInfoIcon.scss';
 import { useToggle } from '../utils/helpers/hooks';
+import './UseExistingIfFoundInfoIcon.scss';
 
 const InfoModal = ({ isOpen, toggle }: { isOpen: boolean; toggle: () => void }) => (
   <Modal isOpen={isOpen} toggle={toggle} centered size="lg">
diff --git a/src/short-urls/helpers/QrCodeModal.tsx b/src/short-urls/helpers/QrCodeModal.tsx
index e26d289a..4bde939e 100644
--- a/src/short-urls/helpers/QrCodeModal.tsx
+++ b/src/short-urls/helpers/QrCodeModal.tsx
@@ -1,5 +1,5 @@
 import { useMemo, useState } from 'react';
-import { DropdownItem, FormGroup, Modal, ModalBody, ModalHeader, Row } from 'reactstrap';
+import { Modal, DropdownItem, FormGroup, ModalBody, ModalHeader, Row } from 'reactstrap';
 import { ExternalLink } from 'react-external-link';
 import classNames from 'classnames';
 import { ShortUrlModalProps } from '../data';
diff --git a/src/short-urls/helpers/ShortUrlsRow.scss b/src/short-urls/helpers/ShortUrlsRow.scss
index 89255646..17ec51ac 100644
--- a/src/short-urls/helpers/ShortUrlsRow.scss
+++ b/src/short-urls/helpers/ShortUrlsRow.scss
@@ -5,7 +5,7 @@
   @media (max-width: $responsiveTableBreakpoint) {
     display: block;
     margin-bottom: 10px;
-    border-bottom: 1px solid $lightGrey;
+    border-bottom: 1px solid var(--border-color);
     position: relative;
   }
 }
diff --git a/src/tags/TagCard.scss b/src/tags/TagCard.scss
index ce6849aa..ecb79abe 100644
--- a/src/tags/TagCard.scss
+++ b/src/tags/TagCard.scss
@@ -1,3 +1,5 @@
+@import '../utils/base';
+
 .tag-card.tag-card {
   margin-bottom: .5rem;
 }
@@ -26,11 +28,11 @@
 }
 
 .tag-card__tag-name {
-  color: #007bff;
+  color: $mainColor;
   cursor: pointer;
 }
 
 .tag-card__tag-name:hover {
-  color: #0056b3;
+  color: darken($mainColor, 15%);
   text-decoration: underline;
 }
diff --git a/src/tags/TagCard.tsx b/src/tags/TagCard.tsx
index d7359b25..b72bca0e 100644
--- a/src/tags/TagCard.tsx
+++ b/src/tags/TagCard.tsx
@@ -35,10 +35,10 @@ const TagCard = (
   return (
     <Card className="tag-card">
       <CardHeader className="tag-card__header">
-        <Button color="light" size="sm" className="tag-card__btn tag-card__btn--last" onClick={toggleDelete}>
+        <Button color="link" size="sm" className="tag-card__btn tag-card__btn--last" onClick={toggleDelete}>
           <FontAwesomeIcon icon={deleteIcon} />
         </Button>
-        <Button color="light" size="sm" className="tag-card__btn" onClick={toggleEdit}>
+        <Button color="link" size="sm" className="tag-card__btn" onClick={toggleEdit}>
           <FontAwesomeIcon icon={editIcon} />
         </Button>
         <h5 className="tag-card__tag-title text-ellipsis">
@@ -57,14 +57,14 @@ const TagCard = (
           <CardBody className="tag-card__body">
             <Link
               to={shortUrlsLink}
-              className="btn btn-light btn-block d-flex justify-content-between align-items-center mb-1"
+              className="btn btn-outline-secondary btn-block d-flex justify-content-between align-items-center mb-1"
             >
               <span className="text-ellipsis"><FontAwesomeIcon icon={faLink} className="mr-2" />Short URLs</span>
               <b>{prettify(tagStats.shortUrlsCount)}</b>
             </Link>
             <Link
               to={`/server/${serverId}/tag/${tag}/visits`}
-              className="btn btn-light btn-block d-flex justify-content-between align-items-center"
+              className="btn btn-outline-secondary btn-block d-flex justify-content-between align-items-center"
             >
               <span className="text-ellipsis"><FontAwesomeIcon icon={faEye} className="mr-2" />Visits</span>
               <b>{prettify(tagStats.visitsCount)}</b>
diff --git a/src/theme/theme.scss b/src/theme/theme.scss
new file mode 100644
index 00000000..e4f8cc64
--- /dev/null
+++ b/src/theme/theme.scss
@@ -0,0 +1,63 @@
+@import '../utils/base';
+
+// Light theme colors
+$lightPrimaryColor: #ffffff;
+$lightPrimaryColorAlfa: rgba($lightPrimaryColor, .5);
+$lightSecondaryColor: $lightColor;
+$lightTextColor: #212529;
+$lightBorderColor: rgba(0, 0, 0, .125);
+$lightTableBorderColor: $mediumGrey;
+$lightActiveColor: $lightGrey;
+$lightBrandColor: $mainColor;
+$lightInputColor: $lightPrimaryColor;
+$lightInputTextColor: #495057;
+$lightDisabledInputColor: $lightColor;
+$lightBorderInputColor: rgba(0, 0, 0, .19);
+$lightTableHighlightColor: rgba(0, 0, 0, .075);
+
+// Dark theme colors
+$darkPrimaryColor: #161b22;
+$darkPrimaryColorAlfa: rgba($darkPrimaryColor, .8);
+$darkSecondaryColor: #0f131a;
+$darkTextColor: rgb(201, 209, 217);
+$darkBorderColor: rgba(255, 255, 255, .15);
+$darkTableBorderColor: #393d43;
+$darkActiveColor: $darkSecondaryColor;
+$darkBrandColor: #0b2d4e;
+$darkInputColor: darken($darkPrimaryColor, 2%);
+$darkInputTextColor: $darkTextColor;
+$darkDisabledInputColor: lighten($darkPrimaryColor, 2%);
+$darkBorderInputColor: $darkBorderColor;
+$darkTableHighlightColor: $darkBorderColor;
+
+html:not([data-theme='dark']) {
+  --primary-color: #{$lightPrimaryColor};
+  --primary-color-alfa: #{$lightPrimaryColorAlfa};
+  --secondary-color: #{$lightSecondaryColor};
+  --text-color: #{$lightTextColor};
+  --border-color: #{$lightBorderColor};
+  --active-color: #{$lightActiveColor};
+  --brand-color: #{$lightBrandColor};
+  --input-color: #{$lightInputColor};
+  --input-disabled-color: #{$lightDisabledInputColor};
+  --input-border-color: #{$lightBorderInputColor};
+  --input-text-color: #{$lightInputTextColor};
+  --table-border-color: #{$lightTableBorderColor};
+  --table-highlight-color: #{$lightTableHighlightColor};
+}
+
+html[data-theme='dark'] {
+  --primary-color: #{$darkPrimaryColor};
+  --primary-color-alfa: #{$darkPrimaryColorAlfa};
+  --secondary-color: #{$darkSecondaryColor};
+  --text-color: #{$darkTextColor};
+  --border-color: #{$darkBorderColor};
+  --active-color: #{$darkActiveColor};
+  --brand-color: #{$darkBrandColor};
+  --input-color: #{$darkInputColor};
+  --input-disabled-color: #{$darkDisabledInputColor};
+  --input-border-color: #{$darkBorderInputColor};
+  --input-text-color: #{$darkInputTextColor};
+  --table-border-color: #{$darkTableBorderColor};
+  --table-highlight-color: #{$darkTableHighlightColor};
+}
diff --git a/src/utils/DateInput.scss b/src/utils/DateInput.scss
index 9653c38b..50c4016a 100644
--- a/src/utils/DateInput.scss
+++ b/src/utils/DateInput.scss
@@ -10,7 +10,12 @@
 }
 
 .date-input-container__input:not(:disabled) {
-  background-color: #ffffff !important;
+  background-color: var(--primary-color) !important;
+}
+
+.card .date-input-container__input:not(:disabled),
+.dropdown .date-input-container__input:not(:disabled) {
+  background-color: var(--input-color) !important;
 }
 
 .date-input-container__icon {
@@ -32,3 +37,66 @@
   background-color: #333333;
   font-size: 14px;
 }
+
+.react-datepicker__input-container,
+.react-datepicker-wrapper {
+  display: block !important;
+}
+
+.react-datepicker__day--keyboard-selected {
+  background-color: $mainColor;
+
+  &:hover {
+    background-color: darken($mainColor, 12%);
+  }
+}
+
+.react-datepicker.react-datepicker {
+  background-color: var(--primary-color);
+  color: var(--text-color);
+  border-color: var(--border-color);
+}
+
+.react-datepicker__header.react-datepicker__header {
+  background-color: var(--secondary-color);
+  border-color: var(--border-color);
+}
+
+.react-datepicker__current-month.react-datepicker__current-month,
+.react-datepicker-time__header.react-datepicker-time__header,
+.react-datepicker-year-header.react-datepicker-year-header,
+.react-datepicker__day-name.react-datepicker__day-name,
+.react-datepicker__day:not(:hover).react-datepicker__day:not(:hover),
+.react-datepicker__time-name.react-datepicker__time-name {
+  color: inherit;
+}
+
+.react-datepicker__day--keyboard-selected.react-datepicker__day--keyboard-selected,
+.react-datepicker__month-text--keyboard-selected.react-datepicker__month-text--keyboard-selected,
+.react-datepicker__quarter-text--keyboard-selected.react-datepicker__quarter-text--keyboard-selected,
+.react-datepicker__year-text--keyboard-selected.react-datepicker__year-text--keyboard-selected {
+  background-color: var(--brand-color) !important;
+  color: white !important;
+}
+
+.react-datepicker-popper.react-datepicker-popper {
+  z-index: 2;
+
+  &[data-placement^='top'] .react-datepicker__triangle.react-datepicker__triangle {
+    border-top-color: var(--primary-color);
+    border-bottom-color: var(--border-color);
+
+    &::before {
+      border-top-color: var(--border-color);
+    }
+  }
+
+  &[data-placement^='bottom'] .react-datepicker__triangle.react-datepicker__triangle {
+    border-top-color: var(--border-color);
+    border-bottom-color: var(--secondary-color);
+
+    &::before {
+      border-bottom-color: var(--border-color);
+    }
+  }
+}
diff --git a/src/utils/DropdownBtn.scss b/src/utils/DropdownBtn.scss
index 6cfae1dc..f5c40c27 100644
--- a/src/utils/DropdownBtn.scss
+++ b/src/utils/DropdownBtn.scss
@@ -1,3 +1,5 @@
+/* stylelint-disable no-descending-specificity */
+
 @import '../utils/mixins/vertical-align';
 
 .dropdown-btn__toggle.dropdown-btn__toggle,
@@ -6,10 +8,24 @@
 .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled):focus,
 .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled):hover,
 .show > .dropdown-btn__toggle.dropdown-btn__toggle.dropdown-toggle {
-  color: #6c757d;
-  background-color: white;
   text-align: left;
-  border-color: rgba(0, 0, 0, .125);
+  color: var(--input-text-color);
+  background-color: var(--primary-color);
+  border-color: var(--input-border-color);
+}
+
+.card .dropdown-btn__toggle.dropdown-btn__toggle,
+.card .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled).active,
+.card .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled):active,
+.card .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled):focus,
+.card .dropdown-btn__toggle.dropdown-btn__toggle:not(:disabled):not(.disabled):hover,
+.show > .card .dropdown-btn__toggle.dropdown-btn__toggle.dropdown-toggle {
+  background-color: var(--input-color);
+}
+
+.dropdown-btn__toggle.dropdown-btn__toggle.disabled,
+.dropdown-btn__toggle.dropdown-btn__toggle:disabled {
+  background-color: var(--input-disabled-color);
 }
 
 .dropdown-btn__toggle.dropdown-btn__toggle:after {
diff --git a/src/utils/base.scss b/src/utils/base.scss
index 8b70dc17..d5c52b2c 100644
--- a/src/utils/base.scss
+++ b/src/utils/base.scss
@@ -12,9 +12,10 @@ $responsiveTableBreakpoint: $mdMax;
 // Colors
 $mainColor: #4696e5;
 $lightColor: #f5f6fe;
-$lightGrey: #dddddd;
+$lightGrey: #eeeeee;
 $dangerColor: #dc3545;
 $mediumGrey: #dee2e6;
+$textPlaceholder: #6c757d;
 
 // Misc
 $headerHeight: 57px;
@@ -23,6 +24,6 @@ $footer-height: 2.3rem;
 $footer-margin: .8rem;
 
 // Bootstrap overwrites
-//$theme-colors: (
-//  'primary': $mainColor
-//);
+$theme-colors: (
+  'primary': $mainColor
+);
diff --git a/src/utils/mixins/sticky-cell.scss b/src/utils/mixins/sticky-cell.scss
index a20f341f..0e2d6125 100644
--- a/src/utils/mixins/sticky-cell.scss
+++ b/src/utils/mixins/sticky-cell.scss
@@ -12,7 +12,7 @@
     left: 0;
     bottom: -1px;
     right: -1px;
-    background: $mediumGrey;
+    background: var(--table-border-color);
     z-index: -2;
   }
 
@@ -27,7 +27,7 @@
     left: 1px;
     bottom: 0;
     right: 0;
-    background: white;
+    background: var(--primary-color);
     z-index: -1;
   }
 
diff --git a/src/utils/theme/index.ts b/src/utils/theme/index.ts
index a4b5f96b..3f47f7eb 100644
--- a/src/utils/theme/index.ts
+++ b/src/utils/theme/index.ts
@@ -2,6 +2,24 @@ export const MAIN_COLOR = '#4696e5';
 
 export const MAIN_COLOR_ALPHA = 'rgba(70, 150, 229, 0.4)';
 
-export const HIGHLIGHTED_COLOR = '#F77F28';
+export const HIGHLIGHTED_COLOR = '#f77f28';
 
 export const HIGHLIGHTED_COLOR_ALPHA = 'rgba(247, 127, 40, 0.4)';
+
+export const PRIMARY_LIGHT_COLOR = 'white';
+
+export const PRIMARY_DARK_COLOR = '#161b22';
+
+export type Theme = 'dark' | 'light';
+
+export const changeThemeInMarkup = (theme: Theme) => {
+  const html = document.getElementsByTagName('html');
+
+  html?.[0]?.setAttribute('data-theme', theme);
+};
+
+export const isDarkThemeEnabled = (): boolean => {
+  const html = document.getElementsByTagName('html');
+
+  return html?.[0]?.getAttribute('data-theme') === 'dark';
+};
diff --git a/src/visits/VisitsStats.scss b/src/visits/VisitsStats.scss
index dc945d12..1caafc6d 100644
--- a/src/visits/VisitsStats.scss
+++ b/src/visits/VisitsStats.scss
@@ -25,6 +25,6 @@
 
 .visits-stats__nav-link.active {
   border-color: $mainColor;
-  background-color: white !important;
+  background-color: var(--primary-color) !important;
   color: $mainColor !important;
 }
diff --git a/src/visits/VisitsTable.scss b/src/visits/VisitsTable.scss
index a8ad3f24..2b20f59c 100644
--- a/src/visits/VisitsTable.scss
+++ b/src/visits/VisitsTable.scss
@@ -4,7 +4,7 @@
 .visits-table {
   margin: 1.5rem 0 0;
   position: relative;
-  background-color: white;
+  background-color: var(--primary-color);
   overflow-y: hidden;
 }
 
diff --git a/src/visits/VisitsTable.tsx b/src/visits/VisitsTable.tsx
index 54e16602..fb99a950 100644
--- a/src/visits/VisitsTable.tsx
+++ b/src/visits/VisitsTable.tsx
@@ -154,7 +154,7 @@ const VisitsTable = ({
             <tr
               key={index}
               style={{ cursor: 'pointer' }}
-              className={classNames({ 'table-primary': isSelected })}
+              className={classNames({ 'table-active': isSelected })}
               onClick={() => setSelectedVisits(
                 isSelected ? selectedVisits.filter((v) => v !== visit) : [ ...selectedVisits, visit ],
               )}
diff --git a/src/visits/helpers/DefaultChart.tsx b/src/visits/helpers/DefaultChart.tsx
index 78d1863a..74dd083a 100644
--- a/src/visits/helpers/DefaultChart.tsx
+++ b/src/visits/helpers/DefaultChart.tsx
@@ -7,7 +7,15 @@ import { fillTheGaps } from '../../utils/helpers/visits';
 import { Stats } from '../types';
 import { prettify } from '../../utils/helpers/numbers';
 import { pointerOnHover, renderDoughnutChartLabel, renderNonDoughnutChartLabel } from '../../utils/helpers/charts';
-import { HIGHLIGHTED_COLOR, HIGHLIGHTED_COLOR_ALPHA, MAIN_COLOR, MAIN_COLOR_ALPHA } from '../../utils/theme';
+import {
+  HIGHLIGHTED_COLOR,
+  HIGHLIGHTED_COLOR_ALPHA,
+  isDarkThemeEnabled,
+  MAIN_COLOR,
+  MAIN_COLOR_ALPHA,
+  PRIMARY_DARK_COLOR,
+  PRIMARY_LIGHT_COLOR,
+} from '../../utils/theme';
 import './DefaultChart.scss';
 
 export interface DefaultChartProps {
@@ -47,7 +55,7 @@ const generateGraphData = (
         '#DCDCDC',
         '#463730',
       ],
-      borderColor: isBarChart ? MAIN_COLOR : 'white',
+      borderColor: isBarChart ? MAIN_COLOR : (isDarkThemeEnabled() ? PRIMARY_DARK_COLOR : PRIMARY_LIGHT_COLOR),
       borderWidth: 2,
     },
     highlightedData && {
diff --git a/test/App.test.tsx b/test/App.test.tsx
index 26938298..da1fda0b 100644
--- a/test/App.test.tsx
+++ b/test/App.test.tsx
@@ -1,6 +1,8 @@
 import { shallow, ShallowWrapper } from 'enzyme';
 import { Route } from 'react-router-dom';
 import { identity } from 'ramda';
+import { Mock } from 'ts-mockery';
+import { Settings } from '../src/settings/reducers/settings';
 import appFactory from '../src/App';
 
 describe('<App />', () => {
@@ -10,7 +12,7 @@ describe('<App />', () => {
   beforeEach(() => {
     const App = appFactory(MainHeader, () => null, () => null, () => null, () => null, () => null, () => null);
 
-    wrapper = shallow(<App fetchServers={identity} servers={{}} />);
+    wrapper = shallow(<App fetchServers={identity} servers={{}} settings={Mock.all<Settings>()} />);
   });
   afterEach(() => wrapper.unmount());
 
diff --git a/test/settings/ShortUrlCreation.test.tsx b/test/settings/ShortUrlCreation.test.tsx
index 07d0bd7b..1cb92d9a 100644
--- a/test/settings/ShortUrlCreation.test.tsx
+++ b/test/settings/ShortUrlCreation.test.tsx
@@ -25,7 +25,7 @@ describe('<ShortUrlCreation />', () => {
     [{ validateUrls: true }, true ],
     [{ validateUrls: false }, false ],
     [ undefined, false ],
-  ])('switch is toggled if option is tru', (shortUrlCreation, expectedChecked) => {
+  ])('switch is toggled if option is true', (shortUrlCreation, expectedChecked) => {
     const wrapper = createWrapper(shortUrlCreation);
     const toggle = wrapper.find(ToggleSwitch);
 
diff --git a/test/settings/UserInterface.test.tsx b/test/settings/UserInterface.test.tsx
new file mode 100644
index 00000000..02a0a037
--- /dev/null
+++ b/test/settings/UserInterface.test.tsx
@@ -0,0 +1,60 @@
+import { shallow, ShallowWrapper } from 'enzyme';
+import { Mock } from 'ts-mockery';
+import { faMoon, faSun } from '@fortawesome/free-solid-svg-icons';
+import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
+import { Settings, UiSettings } from '../../src/settings/reducers/settings';
+import { UserInterface } from '../../src/settings/UserInterface';
+import ToggleSwitch from '../../src/utils/ToggleSwitch';
+import { Theme } from '../../src/utils/theme';
+
+describe('<UserInterface />', () => {
+  let wrapper: ShallowWrapper;
+  const setUiSettings = jest.fn();
+  const createWrapper = (ui?: UiSettings) => {
+    wrapper = shallow(
+      <UserInterface
+        settings={Mock.of<Settings>({ ui })}
+        setUiSettings={setUiSettings}
+      />,
+    );
+
+    return wrapper;
+  };
+
+  afterEach(() => wrapper?.unmount());
+  afterEach(jest.clearAllMocks);
+
+  it.each([
+    [{ theme: 'dark' as Theme }, true ],
+    [{ theme: 'light' as Theme }, false ],
+    [ undefined, false ],
+  ])('toggles switch if theme is dark', (ui, expectedChecked) => {
+    const wrapper = createWrapper(ui);
+    const toggle = wrapper.find(ToggleSwitch);
+
+    expect(toggle.prop('checked')).toEqual(expectedChecked);
+  });
+
+  it.each([
+    [{ theme: 'dark' as Theme }, faMoon ],
+    [{ theme: 'light' as Theme }, faSun ],
+    [ undefined, faSun ],
+  ])('shows different icons based on theme', (ui, expectedIcon) => {
+    const wrapper = createWrapper(ui);
+    const icon = wrapper.find(FontAwesomeIcon);
+
+    expect(icon.prop('icon')).toEqual(expectedIcon);
+  });
+
+  it.each([
+    [ true, 'dark' ],
+    [ false, 'light' ],
+  ])('invokes setUiSettings when toggle value changes', (checked, theme) => {
+    const wrapper = createWrapper();
+    const toggle = wrapper.find(ToggleSwitch);
+
+    expect(setUiSettings).not.toHaveBeenCalled();
+    toggle.simulate('change', checked);
+    expect(setUiSettings).toHaveBeenCalledWith({ theme });
+  });
+});
diff --git a/test/settings/reducers/settings.test.ts b/test/settings/reducers/settings.test.ts
index 1bfd1701..57d22066 100644
--- a/test/settings/reducers/settings.test.ts
+++ b/test/settings/reducers/settings.test.ts
@@ -3,12 +3,14 @@ import reducer, {
   toggleRealTimeUpdates,
   setRealTimeUpdatesInterval,
   setShortUrlCreationSettings,
+  setUiSettings,
 } from '../../../src/settings/reducers/settings';
 
 describe('settingsReducer', () => {
   const realTimeUpdates = { enabled: true };
   const shortUrlCreation = { validateUrls: false };
-  const settings = { realTimeUpdates, shortUrlCreation };
+  const ui = { theme: 'light' };
+  const settings = { realTimeUpdates, shortUrlCreation, ui };
 
   describe('reducer', () => {
     it('returns realTimeUpdates when action is SET_SETTINGS', () => {
@@ -39,4 +41,12 @@ describe('settingsReducer', () => {
       expect(result).toEqual({ type: SET_SETTINGS, shortUrlCreation: { validateUrls: true } });
     });
   });
+
+  describe('setUiSettings', () => {
+    it('creates action to set ui settings', () => {
+      const result = setUiSettings({ theme: 'dark' });
+
+      expect(result).toEqual({ type: SET_SETTINGS, ui: { theme: 'dark' } });
+    });
+  });
 });
diff --git a/test/short-urls/helpers/EditTagsModal.test.tsx b/test/short-urls/helpers/EditTagsModal.test.tsx
index 3da11f62..fddccad0 100644
--- a/test/short-urls/helpers/EditTagsModal.test.tsx
+++ b/test/short-urls/helpers/EditTagsModal.test.tsx
@@ -1,10 +1,10 @@
 import { shallow, ShallowWrapper } from 'enzyme';
-import { Modal } from 'reactstrap';
 import { Mock } from 'ts-mockery';
 import createEditTagsModal from '../../../src/short-urls/helpers/EditTagsModal';
 import { ShortUrl } from '../../../src/short-urls/data';
 import { ShortUrlTags } from '../../../src/short-urls/reducers/shortUrlTags';
 import { OptionalString } from '../../../src/utils/utils';
+import { Modal } from 'reactstrap';
 
 describe('<EditTagsModal />', () => {
   let wrapper: ShallowWrapper;
diff --git a/test/visits/VisitsTable.test.tsx b/test/visits/VisitsTable.test.tsx
index 339233d0..a2d01c4a 100644
--- a/test/visits/VisitsTable.test.tsx
+++ b/test/visits/VisitsTable.test.tsx
@@ -85,7 +85,7 @@ describe('<VisitsTable />', () => {
     );
 
     expect(wrapper.find('.text-primary')).toHaveLength(3);
-    expect(wrapper.find('.table-primary')).toHaveLength(2);
+    expect(wrapper.find('.table-active')).toHaveLength(2);
 
     // Select one extra
     wrapper.find('tr').at(5).simulate('click');
diff --git a/test/visits/helpers/MapModal.test.tsx b/test/visits/helpers/MapModal.test.tsx
index 9c286b11..71cdda26 100644
--- a/test/visits/helpers/MapModal.test.tsx
+++ b/test/visits/helpers/MapModal.test.tsx
@@ -1,8 +1,8 @@
 import { shallow, ShallowWrapper } from 'enzyme';
-import { Modal } from 'reactstrap';
 import { Marker, Popup } from 'react-leaflet';
 import MapModal from '../../../src/visits/helpers/MapModal';
 import { CityStats } from '../../../src/visits/types';
+import { Modal } from 'reactstrap';
 
 describe('<MapModal />', () => {
   let wrapper: ShallowWrapper;