diff --git a/cli/src/api/open-api/api.ts b/cli/src/api/open-api/api.ts
index 8d278b44ce..2133d04113 100644
--- a/cli/src/api/open-api/api.ts
+++ b/cli/src/api/open-api/api.ts
@@ -3307,6 +3307,12 @@ export interface SystemConfigDto {
      * @memberof SystemConfigDto
      */
     'storageTemplate': SystemConfigStorageTemplateDto;
+    /**
+     * 
+     * @type {SystemConfigThemeDto}
+     * @memberof SystemConfigDto
+     */
+    'theme': SystemConfigThemeDto;
     /**
      * 
      * @type {SystemConfigThumbnailDto}
@@ -3741,6 +3747,19 @@ export interface SystemConfigTemplateStorageOptionDto {
      */
     'yearOptions': Array<string>;
 }
+/**
+ * 
+ * @export
+ * @interface SystemConfigThemeDto
+ */
+export interface SystemConfigThemeDto {
+    /**
+     * 
+     * @type {string}
+     * @memberof SystemConfigThemeDto
+     */
+    'customCss': string;
+}
 /**
  * 
  * @export
diff --git a/mobile/openapi/.openapi-generator/FILES b/mobile/openapi/.openapi-generator/FILES
index 85b96e6473..747c435dd3 100644
--- a/mobile/openapi/.openapi-generator/FILES
+++ b/mobile/openapi/.openapi-generator/FILES
@@ -135,6 +135,7 @@ doc/SystemConfigPasswordLoginDto.md
 doc/SystemConfigReverseGeocodingDto.md
 doc/SystemConfigStorageTemplateDto.md
 doc/SystemConfigTemplateStorageOptionDto.md
+doc/SystemConfigThemeDto.md
 doc/SystemConfigThumbnailDto.md
 doc/SystemConfigTrashDto.md
 doc/TagApi.md
@@ -302,6 +303,7 @@ lib/model/system_config_password_login_dto.dart
 lib/model/system_config_reverse_geocoding_dto.dart
 lib/model/system_config_storage_template_dto.dart
 lib/model/system_config_template_storage_option_dto.dart
+lib/model/system_config_theme_dto.dart
 lib/model/system_config_thumbnail_dto.dart
 lib/model/system_config_trash_dto.dart
 lib/model/tag_response_dto.dart
@@ -456,6 +458,7 @@ test/system_config_password_login_dto_test.dart
 test/system_config_reverse_geocoding_dto_test.dart
 test/system_config_storage_template_dto_test.dart
 test/system_config_template_storage_option_dto_test.dart
+test/system_config_theme_dto_test.dart
 test/system_config_thumbnail_dto_test.dart
 test/system_config_trash_dto_test.dart
 test/tag_api_test.dart
diff --git a/mobile/openapi/README.md b/mobile/openapi/README.md
index 47d04b9bd2..07d2cf402f 100644
Binary files a/mobile/openapi/README.md and b/mobile/openapi/README.md differ
diff --git a/mobile/openapi/doc/SystemConfigDto.md b/mobile/openapi/doc/SystemConfigDto.md
index a5b8db773c..d426bef345 100644
Binary files a/mobile/openapi/doc/SystemConfigDto.md and b/mobile/openapi/doc/SystemConfigDto.md differ
diff --git a/mobile/openapi/doc/SystemConfigThemeDto.md b/mobile/openapi/doc/SystemConfigThemeDto.md
new file mode 100644
index 0000000000..bcdbb690cb
Binary files /dev/null and b/mobile/openapi/doc/SystemConfigThemeDto.md differ
diff --git a/mobile/openapi/lib/api.dart b/mobile/openapi/lib/api.dart
index e72c1da168..091a38e36d 100644
Binary files a/mobile/openapi/lib/api.dart and b/mobile/openapi/lib/api.dart differ
diff --git a/mobile/openapi/lib/api_client.dart b/mobile/openapi/lib/api_client.dart
index 34b9a431d4..33586a7e13 100644
Binary files a/mobile/openapi/lib/api_client.dart and b/mobile/openapi/lib/api_client.dart differ
diff --git a/mobile/openapi/lib/model/system_config_dto.dart b/mobile/openapi/lib/model/system_config_dto.dart
index 932e68466b..8e15d7e219 100644
Binary files a/mobile/openapi/lib/model/system_config_dto.dart and b/mobile/openapi/lib/model/system_config_dto.dart differ
diff --git a/mobile/openapi/lib/model/system_config_theme_dto.dart b/mobile/openapi/lib/model/system_config_theme_dto.dart
new file mode 100644
index 0000000000..f34234952d
Binary files /dev/null and b/mobile/openapi/lib/model/system_config_theme_dto.dart differ
diff --git a/mobile/openapi/test/system_config_dto_test.dart b/mobile/openapi/test/system_config_dto_test.dart
index 1a3e38a9e9..30dbe6860b 100644
Binary files a/mobile/openapi/test/system_config_dto_test.dart and b/mobile/openapi/test/system_config_dto_test.dart differ
diff --git a/mobile/openapi/test/system_config_theme_dto_test.dart b/mobile/openapi/test/system_config_theme_dto_test.dart
new file mode 100644
index 0000000000..98e283559e
Binary files /dev/null and b/mobile/openapi/test/system_config_theme_dto_test.dart differ
diff --git a/server/immich-openapi-specs.json b/server/immich-openapi-specs.json
index e6230fcc32..09ff41e24f 100644
--- a/server/immich-openapi-specs.json
+++ b/server/immich-openapi-specs.json
@@ -8060,6 +8060,9 @@
           "storageTemplate": {
             "$ref": "#/components/schemas/SystemConfigStorageTemplateDto"
           },
+          "theme": {
+            "$ref": "#/components/schemas/SystemConfigThemeDto"
+          },
           "thumbnail": {
             "$ref": "#/components/schemas/SystemConfigThumbnailDto"
           },
@@ -8077,7 +8080,8 @@
           "storageTemplate",
           "job",
           "thumbnail",
-          "trash"
+          "trash",
+          "theme"
         ],
         "type": "object"
       },
@@ -8404,6 +8408,17 @@
         ],
         "type": "object"
       },
+      "SystemConfigThemeDto": {
+        "properties": {
+          "customCss": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "customCss"
+        ],
+        "type": "object"
+      },
       "SystemConfigThumbnailDto": {
         "properties": {
           "colorspace": {
diff --git a/server/src/domain/system-config/dto/system-config-theme.dto.ts b/server/src/domain/system-config/dto/system-config-theme.dto.ts
new file mode 100644
index 0000000000..f47b51e0e1
--- /dev/null
+++ b/server/src/domain/system-config/dto/system-config-theme.dto.ts
@@ -0,0 +1,6 @@
+import { IsString } from 'class-validator';
+
+export class SystemConfigThemeDto {
+  @IsString()
+  customCss!: string;
+}
diff --git a/server/src/domain/system-config/dto/system-config.dto.ts b/server/src/domain/system-config/dto/system-config.dto.ts
index 1522683826..6a88e758c6 100644
--- a/server/src/domain/system-config/dto/system-config.dto.ts
+++ b/server/src/domain/system-config/dto/system-config.dto.ts
@@ -9,6 +9,7 @@ import { SystemConfigOAuthDto } from './system-config-oauth.dto';
 import { SystemConfigPasswordLoginDto } from './system-config-password-login.dto';
 import { SystemConfigReverseGeocodingDto } from './system-config-reverse-geocoding.dto';
 import { SystemConfigStorageTemplateDto } from './system-config-storage-template.dto';
+import { SystemConfigThemeDto } from './system-config-theme.dto';
 import { SystemConfigThumbnailDto } from './system-config-thumbnail.dto';
 import { SystemConfigTrashDto } from './system-config-trash.dto';
 
@@ -62,6 +63,11 @@ export class SystemConfigDto implements SystemConfig {
   @ValidateNested()
   @IsObject()
   trash!: SystemConfigTrashDto;
+
+  @Type(() => SystemConfigThemeDto)
+  @ValidateNested()
+  @IsObject()
+  theme!: SystemConfigThemeDto;
 }
 
 export function mapConfig(config: SystemConfig): SystemConfigDto {
diff --git a/server/src/domain/system-config/system-config.core.ts b/server/src/domain/system-config/system-config.core.ts
index 66c72fc92e..4fd2faa295 100644
--- a/server/src/domain/system-config/system-config.core.ts
+++ b/server/src/domain/system-config/system-config.core.ts
@@ -114,6 +114,9 @@ export const defaults = Object.freeze<SystemConfig>({
     enabled: true,
     days: 30,
   },
+  theme: {
+    customCss: '',
+  },
 });
 
 export enum FeatureFlag {
diff --git a/server/src/domain/system-config/system-config.service.spec.ts b/server/src/domain/system-config/system-config.service.spec.ts
index 0444217c09..36cdb6543e 100644
--- a/server/src/domain/system-config/system-config.service.spec.ts
+++ b/server/src/domain/system-config/system-config.service.spec.ts
@@ -115,6 +115,9 @@ const updatedConfig = Object.freeze<SystemConfig>({
     enabled: true,
     days: 10,
   },
+  theme: {
+    customCss: '',
+  },
 });
 
 describe(SystemConfigService.name, () => {
diff --git a/server/src/infra/entities/system-config.entity.ts b/server/src/infra/entities/system-config.entity.ts
index 47b1f69fd9..6bd552111a 100644
--- a/server/src/infra/entities/system-config.entity.ts
+++ b/server/src/infra/entities/system-config.entity.ts
@@ -90,6 +90,8 @@ export enum SystemConfigKey {
 
   TRASH_ENABLED = 'trash.enabled',
   TRASH_DAYS = 'trash.days',
+
+  THEME_CUSTOM_CSS = 'theme.customCss',
 }
 
 export enum TranscodePolicy {
@@ -221,4 +223,7 @@ export interface SystemConfig {
     enabled: boolean;
     days: number;
   };
+  theme: {
+    customCss: string;
+  };
 }
diff --git a/web/src/api/open-api/api.ts b/web/src/api/open-api/api.ts
index 8d278b44ce..2133d04113 100644
--- a/web/src/api/open-api/api.ts
+++ b/web/src/api/open-api/api.ts
@@ -3307,6 +3307,12 @@ export interface SystemConfigDto {
      * @memberof SystemConfigDto
      */
     'storageTemplate': SystemConfigStorageTemplateDto;
+    /**
+     * 
+     * @type {SystemConfigThemeDto}
+     * @memberof SystemConfigDto
+     */
+    'theme': SystemConfigThemeDto;
     /**
      * 
      * @type {SystemConfigThumbnailDto}
@@ -3741,6 +3747,19 @@ export interface SystemConfigTemplateStorageOptionDto {
      */
     'yearOptions': Array<string>;
 }
+/**
+ * 
+ * @export
+ * @interface SystemConfigThemeDto
+ */
+export interface SystemConfigThemeDto {
+    /**
+     * 
+     * @type {string}
+     * @memberof SystemConfigThemeDto
+     */
+    'customCss': string;
+}
 /**
  * 
  * @export
diff --git a/web/src/lib/components/admin-page/settings/setting-textarea.svelte b/web/src/lib/components/admin-page/settings/setting-textarea.svelte
new file mode 100644
index 0000000000..99a672c472
--- /dev/null
+++ b/web/src/lib/components/admin-page/settings/setting-textarea.svelte
@@ -0,0 +1,53 @@
+<script lang="ts">
+  import { quintOut } from 'svelte/easing';
+  import { fly } from 'svelte/transition';
+
+  export let value: string;
+  export let label = '';
+  export let desc = '';
+  export let required = false;
+  export let disabled = false;
+  export let isEdited = false;
+
+  const handleInput = (e: Event) => {
+    value = (e.target as HTMLInputElement).value;
+  };
+</script>
+
+<div class="mb-4 w-full">
+  <div class={`flex h-[26px] place-items-center gap-1`}>
+    <label class={`immich-form-label text-sm`} for={label}>{label}</label>
+    {#if required}
+      <div class="text-red-400">*</div>
+    {/if}
+
+    {#if isEdited}
+      <div
+        transition:fly={{ x: 10, duration: 200, easing: quintOut }}
+        class="rounded-full bg-orange-100 px-2 text-[10px] text-orange-900"
+      >
+        Unsaved change
+      </div>
+    {/if}
+  </div>
+
+  {#if desc}
+    <p class="immich-form-label pb-2 text-sm" id="{label}-desc">
+      {desc}
+    </p>
+  {:else}
+    <slot name="desc" />
+  {/if}
+
+  <textarea
+    class="immich-form-input w-full pb-2"
+    aria-describedby={desc ? `${label}-desc` : undefined}
+    aria-labelledby="{label}-label"
+    id={label}
+    name={label}
+    {required}
+    {value}
+    on:input={handleInput}
+    {disabled}
+  />
+</div>
diff --git a/web/src/lib/components/admin-page/settings/theme/theme-settings.svelte b/web/src/lib/components/admin-page/settings/theme/theme-settings.svelte
new file mode 100644
index 0000000000..b28d0106d2
--- /dev/null
+++ b/web/src/lib/components/admin-page/settings/theme/theme-settings.svelte
@@ -0,0 +1,98 @@
+<script lang="ts">
+  import {
+    notificationController,
+    NotificationType,
+  } from '$lib/components/shared-components/notification/notification';
+  import { handleError } from '$lib/utils/handle-error';
+  import { api, SystemConfigThemeDto } from '@api';
+  import { isEqual } from 'lodash-es';
+  import { fade } from 'svelte/transition';
+  import SettingButtonsRow from '../setting-buttons-row.svelte';
+  import SettingTextarea from '../setting-textarea.svelte';
+
+  export let themeConfig: SystemConfigThemeDto; // this is the config that is being edited
+  export let disabled = false;
+
+  let savedConfig: SystemConfigThemeDto;
+  let defaultConfig: SystemConfigThemeDto;
+
+  async function getConfigs() {
+    [savedConfig, defaultConfig] = await Promise.all([
+      api.systemConfigApi.getConfig().then((res) => res.data.theme),
+      api.systemConfigApi.getDefaults().then((res) => res.data.theme),
+    ]);
+  }
+
+  async function saveSetting() {
+    try {
+      const { data: current } = await api.systemConfigApi.getConfig();
+
+      const { data: updated } = await api.systemConfigApi.updateConfig({
+        systemConfigDto: {
+          ...current,
+          theme: themeConfig,
+        },
+      });
+
+      themeConfig = { ...updated.theme };
+      savedConfig = { ...updated.theme };
+
+      notificationController.show({ message: 'Theme saved', type: NotificationType.Info });
+    } catch (error) {
+      handleError(error, 'Unable to save settings');
+    }
+  }
+
+  async function reset() {
+    const { data: resetConfig } = await api.systemConfigApi.getConfig();
+
+    themeConfig = { ...resetConfig.theme };
+    savedConfig = { ...resetConfig.theme };
+
+    notificationController.show({
+      message: 'Reset theme to the recent saved theme',
+      type: NotificationType.Info,
+    });
+  }
+
+  async function resetToDefault() {
+    const { data: configs } = await api.systemConfigApi.getDefaults();
+
+    themeConfig = { ...configs.theme };
+    defaultConfig = { ...configs.theme };
+
+    notificationController.show({
+      message: 'Reset theme to default',
+      type: NotificationType.Info,
+    });
+  }
+</script>
+
+<div>
+  {#await getConfigs() then}
+    <div in:fade={{ duration: 500 }}>
+      <form autocomplete="off" on:submit|preventDefault>
+        <div class="ml-4 mt-4 flex flex-col gap-4">
+          <div class="ml-4">
+            <SettingTextarea
+              {disabled}
+              label="Custom CSS"
+              desc="Cascading Style Sheets allow the design of Immich to be customized."
+              bind:value={themeConfig.customCss}
+              required={true}
+              isEdited={themeConfig.customCss !== savedConfig.customCss}
+            />
+
+            <SettingButtonsRow
+              on:reset={reset}
+              on:save={saveSetting}
+              on:reset-to-default={resetToDefault}
+              showResetToDefault={!isEqual(savedConfig, defaultConfig)}
+              {disabled}
+            />
+          </div>
+        </div>
+      </form>
+    </div>
+  {/await}
+</div>
diff --git a/web/src/routes/+layout.svelte b/web/src/routes/+layout.svelte
index fbe83775f6..a0cc96aba8 100644
--- a/web/src/routes/+layout.svelte
+++ b/web/src/routes/+layout.svelte
@@ -67,6 +67,7 @@
 <svelte:head>
   <title>{$page.data.meta?.title || 'Web'} - Immich</title>
   <link rel="manifest" href="/manifest.json" />
+  <link rel="stylesheet" href="/custom.css" />
   <meta name="theme-color" content="currentColor" />
   <FaviconHeader />
   <AppleHeader />
diff --git a/web/src/routes/admin/system-settings/+page.svelte b/web/src/routes/admin/system-settings/+page.svelte
index 0f2b2dd7df..04a46bbed0 100644
--- a/web/src/routes/admin/system-settings/+page.svelte
+++ b/web/src/routes/admin/system-settings/+page.svelte
@@ -10,6 +10,7 @@
   import StorageTemplateSettings from '$lib/components/admin-page/settings/storage-template/storage-template-settings.svelte';
   import ThumbnailSettings from '$lib/components/admin-page/settings/thumbnail/thumbnail-settings.svelte';
   import TrashSettings from '$lib/components/admin-page/settings/trash-settings/trash-settings.svelte';
+  import ThemeSettings from '$lib/components/admin-page/settings/theme/theme-settings.svelte';
   import LinkButton from '$lib/components/elements/buttons/link-button.svelte';
   import UserPageLayout from '$lib/components/layouts/user-page-layout.svelte';
   import { downloadManager } from '$lib/stores/download';
@@ -96,6 +97,10 @@
         />
       </SettingAccordion>
 
+      <SettingAccordion title="Theme Settings" subtitle="Manage customization of the Immich web interface">
+        <ThemeSettings disabled={$featureFlags.configFile} themeConfig={configs.theme} />
+      </SettingAccordion>
+
       <SettingAccordion title="Thumbnail Settings" subtitle="Manage the resolution of thumbnail sizes">
         <ThumbnailSettings disabled={$featureFlags.configFile} thumbnailConfig={configs.thumbnail} />
       </SettingAccordion>
diff --git a/web/src/routes/custom.css/+server.ts b/web/src/routes/custom.css/+server.ts
new file mode 100644
index 0000000000..acf8e6d105
--- /dev/null
+++ b/web/src/routes/custom.css/+server.ts
@@ -0,0 +1,9 @@
+import { RequestHandler, text } from '@sveltejs/kit';
+export const GET = (async ({ locals: { api } }) => {
+  const { customCss } = await api.systemConfigApi.getConfig().then((res) => res.data.theme);
+  return text(customCss, {
+    headers: {
+      'Content-Type': 'text/css',
+    },
+  });
+}) satisfies RequestHandler;