diff --git a/components/account/AccountPostsFollowers.vue b/components/account/AccountPostsFollowers.vue
index f2e1cbcc..98dcd4c2 100644
--- a/components/account/AccountPostsFollowers.vue
+++ b/components/account/AccountPostsFollowers.vue
@@ -4,6 +4,8 @@ import type { mastodon } from 'masto'
 defineProps<{
   account: mastodon.v1.Account
 }>()
+
+const userSettings = useUserSettings()
 </script>
 
 <template>
@@ -38,7 +40,7 @@ defineProps<{
       </template>
     </NuxtLink>
     <NuxtLink
-      v-if="!getWellnessSetting('hideFollowerCount')"
+      v-if="!getWellnessSetting(userSettings, 'hideFollowerCount')"
       :to="getAccountFollowersRoute(account)"
       replace text-secondary
       exact-active-class="text-primary"
diff --git a/components/nav/NavBottomMoreMenu.vue b/components/nav/NavBottomMoreMenu.vue
index 3d124c8c..5cb3321d 100644
--- a/components/nav/NavBottomMoreMenu.vue
+++ b/components/nav/NavBottomMoreMenu.vue
@@ -4,6 +4,8 @@ let { modelValue } = $defineModel<{
 }>()
 const colorMode = useColorMode()
 
+const userSettings = useUserSettings()
+
 function toggleVisible() {
   modelValue = !modelValue
 }
diff --git a/components/nav/NavFooter.vue b/components/nav/NavFooter.vue
index ebe7f9b9..ed8fb042 100644
--- a/components/nav/NavFooter.vue
+++ b/components/nav/NavFooter.vue
@@ -2,6 +2,8 @@
 const buildInfo = useRuntimeConfig().public.buildInfo
 const timeAgoOptions = useTimeAgoOptions()
 
+const userSettings = useUserSettings()
+
 const buildTimeDate = new Date(buildInfo.time)
 const buildTimeAgo = useTimeAgo(buildTimeDate, timeAgoOptions)
 
diff --git a/components/settings/SettingsColorMode.vue b/components/settings/SettingsColorMode.vue
index 2a0f5b72..86649723 100644
--- a/components/settings/SettingsColorMode.vue
+++ b/components/settings/SettingsColorMode.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import type { ColorMode } from '~/types'
+import type { ColorMode } from '~/composables/settings'
 
 const colorMode = useColorMode()
 
diff --git a/components/settings/SettingsFontSize.vue b/components/settings/SettingsFontSize.vue
index 91d5dfc0..24207113 100644
--- a/components/settings/SettingsFontSize.vue
+++ b/components/settings/SettingsFontSize.vue
@@ -1,14 +1,15 @@
 <script lang="ts" setup>
 import { DEFAULT_FONT_SIZE } from '~/constants'
-import type { FontSize } from '~/types'
+import type { FontSize } from '~/composables/settings'
+
+const userSettings = useUserSettings()
 
 const sizes = ['xs', 'sm', 'md', 'lg', 'xl'] as FontSize[]
-const fontSize = useFontSizeRef()
 </script>
 
 <template>
-  <select v-model="fontSize">
-    <option v-for="size in sizes" :key="size" :value="size" :selected="fontSize === size">
+  <select v-model="userSettings.fontSize">
+    <option v-for="size in sizes" :key="size" :value="size" :selected="userSettings.fontSize === size">
       {{ `${$t(`settings.interface.size_label.${size}`)}${size === DEFAULT_FONT_SIZE ? $t('settings.interface.default') : ''}` }}
     </option>
   </select>
diff --git a/components/settings/SettingsLanguage.vue b/components/settings/SettingsLanguage.vue
index ab535e11..a1c87c1f 100644
--- a/components/settings/SettingsLanguage.vue
+++ b/components/settings/SettingsLanguage.vue
@@ -2,13 +2,14 @@
 import type { ComputedRef } from 'vue'
 import type { LocaleObject } from '#i18n'
 
-const { locale, setLocale } = useI18n()
+const userSettings = useUserSettings()
+
 const { locales } = useI18n() as { locales: ComputedRef<LocaleObject[]> }
 </script>
 
 <template>
-  <select :value="locale" @input="e => setLocale((e.target as any).value)">
-    <option v-for="item in locales" :key="item.code" :value="item.code" :selected="locale === item.code">
+  <select v-model="userSettings.language">
+    <option v-for="item in locales" :key="item.code" :value="item.code" :selected="userSettings.language === item.code">
       {{ item.name }}
     </option>
   </select>
diff --git a/components/status/StatusActions.vue b/components/status/StatusActions.vue
index 61710810..44c16dad 100644
--- a/components/status/StatusActions.vue
+++ b/components/status/StatusActions.vue
@@ -11,6 +11,8 @@ const focusEditor = inject<typeof noop>('focus-editor', noop)
 
 const { details, command } = $(props)
 
+const userSettings = useUserSettings()
+
 const {
   status,
   isLoading,
@@ -53,7 +55,7 @@ const reply = () => {
     <div flex-1>
       <StatusActionButton
         :content="$t('action.boost')"
-        :text="!getWellnessSetting('hideBoostCount') && status.reblogsCount ? status.reblogsCount : ''"
+        :text="!getWellnessSetting(userSettings, 'hideBoostCount') && status.reblogsCount ? status.reblogsCount : ''"
         color="text-green" hover="text-green" group-hover="bg-green/10"
         icon="i-ri:repeat-line"
         active-icon="i-ri:repeat-fill"
@@ -62,7 +64,7 @@ const reply = () => {
         :command="command"
         @click="toggleReblog()"
       >
-        <template v-if="status.reblogsCount && !getWellnessSetting('hideBoostCount')" #text>
+        <template v-if="status.reblogsCount && !getWellnessSetting(userSettings, 'hideBoostCount')" #text>
           <CommonLocalizedNumber
             keypath="action.boost_count"
             :count="status.reblogsCount"
@@ -74,7 +76,7 @@ const reply = () => {
     <div flex-1>
       <StatusActionButton
         :content="$t('action.favourite')"
-        :text="!getWellnessSetting('hideFavoriteCount') && status.favouritesCount ? status.favouritesCount : ''"
+        :text="!getWellnessSetting(userSettings, 'hideFavoriteCount') && status.favouritesCount ? status.favouritesCount : ''"
         color="text-rose" hover="text-rose" group-hover="bg-rose/10"
         icon="i-ri:heart-3-line"
         active-icon="i-ri:heart-3-fill"
@@ -83,7 +85,7 @@ const reply = () => {
         :command="command"
         @click="toggleFavourite()"
       >
-        <template v-if="status.favouritesCount && !getWellnessSetting('hideFavoriteCount')" #text>
+        <template v-if="status.favouritesCount && !getWellnessSetting(userSettings, 'hideFavoriteCount')" #text>
           <CommonLocalizedNumber
             keypath="action.favourite_count"
             :count="status.favouritesCount"
diff --git a/components/status/StatusActionsMore.vue b/components/status/StatusActionsMore.vue
index bf4fd412..29af77e1 100644
--- a/components/status/StatusActionsMore.vue
+++ b/components/status/StatusActionsMore.vue
@@ -23,6 +23,7 @@ const clipboard = useClipboard()
 const router = useRouter()
 const route = useRoute()
 const { t } = useI18n()
+const userSettings = useUserSettings()
 
 const isAuthor = $computed(() => status.account.id === currentUser.value?.account.id)
 
diff --git a/components/status/StatusCard.vue b/components/status/StatusCard.vue
index 9e227114..2fc94e0c 100644
--- a/components/status/StatusCard.vue
+++ b/components/status/StatusCard.vue
@@ -22,6 +22,7 @@ const props = withDefaults(
   }>(),
   { actions: true },
 )
+const userSettings = useUserSettings()
 
 const status = $computed(() => {
   if (props.status.reblog && !props.status.content)
diff --git a/composables/command.ts b/composables/command.ts
index 1a73918d..aa8c48d1 100644
--- a/composables/command.ts
+++ b/composables/command.ts
@@ -244,6 +244,7 @@ export const provideGlobalCommands = () => {
   const users = useUsers()
   const masto = useMasto()
   const colorMode = useColorMode()
+  const userSettings = useUserSettings()
 
   useCommand({
     scope: 'Navigation',
diff --git a/composables/injections.ts b/composables/injections.ts
index c43e910f..b304fbc1 100644
--- a/composables/injections.ts
+++ b/composables/injections.ts
@@ -1,8 +1,4 @@
-import { InjectionKeyDropdownContext, InjectionKeyFontSize } from '~/constants/symbols'
-
-export function useFontSizeRef() {
-  return inject(InjectionKeyFontSize)!
-}
+import { InjectionKeyDropdownContext } from '~/constants/symbols'
 
 export function useDropdownContext() {
   return inject(InjectionKeyDropdownContext, undefined)
diff --git a/composables/settings/definition.ts b/composables/settings/definition.ts
new file mode 100644
index 00000000..951be211
--- /dev/null
+++ b/composables/settings/definition.ts
@@ -0,0 +1,46 @@
+import { DEFAULT_FONT_SIZE, DEFAULT_LANGUAGE } from '~/constants'
+
+export type FontSize = 'xs' | 'sm' | 'md' | 'lg' | 'xl'
+export type ColorMode = 'light' | 'dark'
+
+export interface FeatureFlags {
+  experimentalVirtualScroller: boolean
+  experimentalGitHubCards: boolean
+  experimentalUserPicker: boolean
+}
+
+export interface WellnessSettings {
+  hideBoostCount: boolean
+  hideFavoriteCount: boolean
+  hideFollowerCount: boolean
+}
+
+export interface UserSettings {
+  featureFlags: Partial<FeatureFlags>
+  wellnessSettings: Partial<WellnessSettings>
+  colorMode?: ColorMode
+  fontSize: FontSize
+  language: string
+  zenMode?: boolean
+}
+
+export function getDefaultUserSettings(): UserSettings {
+  return {
+    language: DEFAULT_LANGUAGE,
+    fontSize: DEFAULT_FONT_SIZE,
+    featureFlags: {},
+    wellnessSettings: {},
+  }
+}
+
+export const DEFAULT_WELLNESS_SETTINGS: WellnessSettings = {
+  hideBoostCount: false,
+  hideFavoriteCount: false,
+  hideFollowerCount: false,
+}
+
+export const DEFAULT_FEATURE_FLAGS: FeatureFlags = {
+  experimentalVirtualScroller: true,
+  experimentalGitHubCards: true,
+  experimentalUserPicker: true,
+}
diff --git a/composables/settings/featureFlags.ts b/composables/settings/featureFlags.ts
deleted file mode 100644
index 611f6a77..00000000
--- a/composables/settings/featureFlags.ts
+++ /dev/null
@@ -1,36 +0,0 @@
-import type { Ref } from 'vue'
-import { userSettings } from '.'
-
-export interface FeatureFlags {
-  experimentalVirtualScroller: boolean
-  experimentalGitHubCards: boolean
-  experimentalUserPicker: boolean
-}
-export type FeatureFlagsMap = Record<string, FeatureFlags>
-
-const DEFAULT_FEATURE_FLAGS: FeatureFlags = {
-  experimentalVirtualScroller: true,
-  experimentalGitHubCards: true,
-  experimentalUserPicker: true,
-}
-
-export function useFeatureFlag<T extends keyof FeatureFlags>(name: T): Ref<FeatureFlags[T]> {
-  return computed({
-    get() {
-      return getFeatureFlag(name)
-    },
-    set(value) {
-      if (userSettings.value)
-        userSettings.value.featureFlags[name] = value
-    },
-  })
-}
-
-export function getFeatureFlag<T extends keyof FeatureFlags>(name: T): FeatureFlags[T] {
-  return userSettings.value?.featureFlags?.[name] ?? DEFAULT_FEATURE_FLAGS[name]
-}
-
-export function toggleFeatureFlag(key: keyof FeatureFlags) {
-  const flag = useFeatureFlag(key)
-  flag.value = !flag.value
-}
diff --git a/composables/settings/index.ts b/composables/settings/index.ts
index e53fb847..556503f5 100644
--- a/composables/settings/index.ts
+++ b/composables/settings/index.ts
@@ -1,24 +1,2 @@
-import type { FeatureFlags } from './featureFlags'
-import type { WellnessSettings } from './wellness'
-import type { ColorMode, FontSize } from '~/types'
-import { STORAGE_KEY_SETTINGS } from '~/constants'
-
-export interface UserSettings {
-  featureFlags: Partial<FeatureFlags>
-  wellnessSettings: Partial<WellnessSettings>
-  colorMode?: ColorMode
-  fontSize?: FontSize
-  lang?: string
-  zenMode?: boolean
-}
-
-export function getDefaultUserSettings(): UserSettings {
-  return {
-    featureFlags: {},
-    wellnessSettings: {},
-  }
-}
-
-export const userSettings = process.server
-  ? computed(getDefaultUserSettings)
-  : useUserLocalStorage(STORAGE_KEY_SETTINGS, getDefaultUserSettings)
+export * from './definition'
+export * from './storage'
diff --git a/composables/settings/storage.ts b/composables/settings/storage.ts
new file mode 100644
index 00000000..917e398e
--- /dev/null
+++ b/composables/settings/storage.ts
@@ -0,0 +1,53 @@
+import type { Ref } from 'vue'
+import type { FeatureFlags, UserSettings, WellnessSettings } from './definition'
+import { STORAGE_KEY_SETTINGS } from '~/constants'
+
+export const useUserSettings = () => {
+  if (process.server)
+    return useState('user-settings', getDefaultUserSettings)
+  return useUserLocalStorage(STORAGE_KEY_SETTINGS, getDefaultUserSettings)
+}
+
+// TODO: refactor & simplify this
+
+export function useWellnessSetting<T extends keyof WellnessSettings>(name: T): Ref<WellnessSettings[T]> {
+  const userSettings = useUserSettings()
+  return computed({
+    get() {
+      return getWellnessSetting(userSettings.value, name)
+    },
+    set(value) {
+      userSettings.value.wellnessSettings[name] = value
+    },
+  })
+}
+
+export function getWellnessSetting<T extends keyof WellnessSettings>(userSettings: UserSettings, name: T): WellnessSettings[T] {
+  return userSettings?.wellnessSettings?.[name] ?? DEFAULT_WELLNESS_SETTINGS[name]
+}
+
+export function toggleWellnessSetting(key: keyof WellnessSettings) {
+  const flag = useWellnessSetting(key)
+  flag.value = !flag.value
+}
+
+export function useFeatureFlag<T extends keyof FeatureFlags>(name: T): Ref<FeatureFlags[T]> {
+  const userSettings = useUserSettings()
+  return computed({
+    get() {
+      return getFeatureFlag(userSettings.value, name)
+    },
+    set(value) {
+      userSettings.value.featureFlags[name] = value
+    },
+  })
+}
+
+export function getFeatureFlag<T extends keyof FeatureFlags>(userSettings: UserSettings, name: T): FeatureFlags[T] {
+  return userSettings?.featureFlags?.[name] ?? DEFAULT_FEATURE_FLAGS[name]
+}
+
+export function toggleFeatureFlag(key: keyof FeatureFlags) {
+  const flag = useFeatureFlag(key)
+  flag.value = !flag.value
+}
diff --git a/composables/settings/wellness.ts b/composables/settings/wellness.ts
deleted file mode 100644
index 164365e6..00000000
--- a/composables/settings/wellness.ts
+++ /dev/null
@@ -1,36 +0,0 @@
-import type { Ref } from 'vue'
-import { userSettings } from '.'
-
-export interface WellnessSettings {
-  hideBoostCount: boolean
-  hideFavoriteCount: boolean
-  hideFollowerCount: boolean
-}
-export type WellnessSettingsMap = Record<string, WellnessSettings>
-
-const DEFAULT_WELLNESS_SETTINGS: WellnessSettings = {
-  hideBoostCount: false,
-  hideFavoriteCount: false,
-  hideFollowerCount: false,
-}
-
-export function useWellnessSetting<T extends keyof WellnessSettings>(name: T): Ref<WellnessSettings[T]> {
-  return computed({
-    get() {
-      return getWellnessSetting(name)
-    },
-    set(value) {
-      if (userSettings.value)
-        userSettings.value.wellnessSettings[name] = value
-    },
-  })
-}
-
-export function getWellnessSetting<T extends keyof WellnessSettings>(name: T): WellnessSettings[T] {
-  return userSettings.value?.wellnessSettings?.[name] ?? DEFAULT_WELLNESS_SETTINGS[name]
-}
-
-export function toggleWellnessSetting(key: keyof WellnessSettings) {
-  const flag = useWellnessSetting(key)
-  flag.value = !flag.value
-}
diff --git a/composables/users.ts b/composables/users.ts
index 9af04f68..6bad13b8 100644
--- a/composables/users.ts
+++ b/composables/users.ts
@@ -271,13 +271,7 @@ export function checkLogin() {
  * Create reactive storage for the current user
  */
 export function useUserLocalStorage<T extends object>(key: string, initial: () => T) {
-  // @ts-expect-error bind value to the function
-  const storages = useUserLocalStorage._ = useUserLocalStorage._ || new Map<string, Ref<Record<string, any>>>()
-
-  if (!storages.has(key))
-    storages.set(key, useLocalStorage(key, {}, { deep: true }))
-  const all = storages.get(key) as Ref<Record<string, T>>
-
+  const all = useLocalStorage<Record<string, T>>(key, {}, { deep: true })
   return computed(() => {
     const id = currentUser.value?.account.id
       ? currentUser.value.account.acct
diff --git a/constants/index.ts b/constants/index.ts
index 2c33a9ca..bbe25a44 100644
--- a/constants/index.ts
+++ b/constants/index.ts
@@ -2,6 +2,7 @@ export const APP_NAME = 'Elk'
 
 export const DEFAULT_POST_CHARS_LIMIT = 500
 export const DEFAULT_FONT_SIZE = 'md'
+export const DEFAULT_LANGUAGE = 'en-US'
 
 export const STORAGE_KEY_DRAFTS = 'elk-drafts'
 export const STORAGE_KEY_USERS = 'elk-users'
@@ -20,7 +21,6 @@ export const STORAGE_KEY_NOTIFICATION_POLICY = 'elk-notification-policy'
 export const COOKIE_MAX_AGE = 10 * 365 * 24 * 60 * 60 * 1000
 
 export const COOKIE_KEY_FONT_SIZE = 'elk-font-size'
-export const COOKIE_KEY_COLOR_MODE = 'elk-color-mode'
 export const COOKIE_KEY_LOCALE = 'elk-lang'
 
 export const HANDLED_MASTO_URLS = /^(https?:\/\/)?([\w\d-]+\.)+\w+\/(@[@\w\d-\.]+)(\/objects)?(\/\d+)?$/
diff --git a/constants/symbols.ts b/constants/symbols.ts
index bf8a9291..8e04e1b4 100644
--- a/constants/symbols.ts
+++ b/constants/symbols.ts
@@ -1,7 +1,4 @@
-import type { InjectionKey, Ref } from 'vue'
-import type { FontSize } from '~/types'
-
-export const InjectionKeyFontSize: InjectionKey<Ref<FontSize>> = Symbol('font-size')
+import type { InjectionKey } from 'vue'
 
 export const InjectionKeyDropdownContext: InjectionKey<{
   hide: () => void
diff --git a/layouts/default.vue b/layouts/default.vue
index bff152d8..4bd08925 100644
--- a/layouts/default.vue
+++ b/layouts/default.vue
@@ -1,7 +1,8 @@
 <script lang="ts" setup>
-import { useFeatureFlag } from '~~/composables/settings/featureFlags'
+import { useFeatureFlag } from '~/composables/settings'
 
 const route = useRoute()
+const userSettings = useUserSettings()
 
 const wideLayout = computed(() => route.meta.wideLayout ?? false)
 
diff --git a/pages/settings/preferences/index.vue b/pages/settings/preferences/index.vue
index 9981b4da..45b87813 100644
--- a/pages/settings/preferences/index.vue
+++ b/pages/settings/preferences/index.vue
@@ -4,6 +4,8 @@ const { t } = useI18n()
 useHeadFixed({
   title: () => `${t('settings.preferences.label')} | ${t('nav.settings')}`,
 })
+
+const userSettings = useUserSettings()
 </script>
 
 <template>
@@ -18,19 +20,19 @@ useHeadFixed({
       {{ $t('settings.feature_flags.title') }}
     </h3>
     <SettingsToggleItem
-      :checked="getFeatureFlag('experimentalVirtualScroller')"
+      :checked="getFeatureFlag(userSettings, 'experimentalVirtualScroller')"
       @click="toggleFeatureFlag('experimentalVirtualScroller')"
     >
       {{ $t('settings.feature_flags.virtual_scroll') }}
     </SettingsToggleItem>
     <SettingsToggleItem
-      :checked="getFeatureFlag('experimentalGitHubCards')"
+      :checked="getFeatureFlag(userSettings, 'experimentalGitHubCards')"
       @click="toggleFeatureFlag('experimentalGitHubCards')"
     >
       {{ $t('settings.feature_flags.github_cards') }}
     </SettingsToggleItem>
     <SettingsToggleItem
-      :checked="getFeatureFlag('experimentalUserPicker')"
+      :checked="getFeatureFlag(userSettings, 'experimentalUserPicker')"
       @click="toggleFeatureFlag('experimentalUserPicker')"
     >
       {{ $t('settings.feature_flags.user_picker') }}
diff --git a/pages/settings/wellness/index.vue b/pages/settings/wellness/index.vue
index 14b6e0fa..546dbb93 100644
--- a/pages/settings/wellness/index.vue
+++ b/pages/settings/wellness/index.vue
@@ -4,6 +4,8 @@ const { t } = useI18n()
 useHeadFixed({
   title: () => `${t('settings.wellness.label')} | ${t('nav.settings')}`,
 })
+
+const userSettings = useUserSettings()
 </script>
 
 <template>
@@ -14,19 +16,19 @@ useHeadFixed({
       </div>
     </template>
     <SettingsToggleItem
-      :checked="getWellnessSetting('hideBoostCount')"
+      :checked="getWellnessSetting(userSettings, 'hideBoostCount')"
       @click="toggleWellnessSetting('hideBoostCount')"
     >
       {{ $t('settings.wellness.feature.hide_boost_count') }}
     </SettingsToggleItem>
     <SettingsToggleItem
-      :checked="getWellnessSetting('hideFavoriteCount')"
+      :checked="getWellnessSetting(userSettings, 'hideFavoriteCount')"
       @click="toggleWellnessSetting('hideFavoriteCount')"
     >
       {{ $t('settings.wellness.feature.hide_favorite_count') }}
     </SettingsToggleItem>
     <SettingsToggleItem
-      :checked="getWellnessSetting('hideFollowerCount')"
+      :checked="getWellnessSetting(userSettings, 'hideFollowerCount')"
       @click="toggleWellnessSetting('hideFollowerCount')"
     >
       {{ $t('settings.wellness.feature.hide_follower_count') }}
diff --git a/plugins/setup-font-size.ts b/plugins/setup-font-size.ts
index 0819506a..eb61992e 100644
--- a/plugins/setup-font-size.ts
+++ b/plugins/setup-font-size.ts
@@ -1,24 +1,26 @@
-import type { FontSize } from '~/types'
-import { InjectionKeyFontSize } from '~/constants/symbols'
+import type { FontSize } from '~/composables/settings'
 import { COOKIE_KEY_FONT_SIZE, COOKIE_MAX_AGE, DEFAULT_FONT_SIZE } from '~/constants'
 import { fontSizeMap } from '~/constants/options'
 
-export default defineNuxtPlugin((nuxt) => {
+export default defineNuxtPlugin(() => {
+  const userSettings = useUserSettings()
   const cookieFontSize = useCookie<FontSize>(COOKIE_KEY_FONT_SIZE, { default: () => DEFAULT_FONT_SIZE, maxAge: COOKIE_MAX_AGE })
-  nuxt.vueApp.provide(InjectionKeyFontSize, cookieFontSize)
+  if (!cookieFontSize.value || !fontSizeMap[cookieFontSize.value])
+    cookieFontSize.value = DEFAULT_FONT_SIZE
 
-  if (!process.server) {
-    watchEffect(() => {
-      document.documentElement.style.setProperty('--font-size', fontSizeMap[cookieFontSize.value || DEFAULT_FONT_SIZE])
-    })
-  }
-  else {
+  if (process.server) {
+    userSettings.value.fontSize = cookieFontSize.value
     useHead({
       style: [
-        {
-          innerHTML: `:root { --font-size: ${fontSizeMap[cookieFontSize.value || DEFAULT_FONT_SIZE]}; }`,
-        },
+        { innerHTML: `:root { --font-size: ${fontSizeMap[cookieFontSize.value]}; }` },
       ],
     })
+    return
   }
+
+  userSettings.value.fontSize = cookieFontSize.value
+  watch(() => userSettings.value.fontSize, (size) => {
+    document.documentElement.style.setProperty('--font-size', fontSizeMap[size])
+    cookieFontSize.value = size
+  }, { immediate: true })
 })
diff --git a/plugins/setup-i18n.ts b/plugins/setup-i18n.ts
index aedeec9b..c9a1cdac 100644
--- a/plugins/setup-i18n.ts
+++ b/plugins/setup-i18n.ts
@@ -1,26 +1,46 @@
-import { COOKIE_KEY_LOCALE, COOKIE_MAX_AGE } from '~/constants'
+import type { VueI18n } from 'vue-i18n'
+import type { LocaleObject } from 'vue-i18n-routing'
+import { COOKIE_KEY_LOCALE, COOKIE_MAX_AGE, DEFAULT_LANGUAGE } from '~/constants'
 
 export default defineNuxtPlugin(async (nuxt) => {
-  const i18n = nuxt.vueApp.config.globalProperties.$i18n
-  const { setLocale, locales } = nuxt.vueApp.config.globalProperties.$i18n
+  const i18n = nuxt.vueApp.config.globalProperties.$i18n as VueI18n
+  const { setLocale, locales } = i18n
+  const supportLanguages = (locales as LocaleObject[]).map(locale => locale.code)
   const cookieLocale = useCookie(COOKIE_KEY_LOCALE, { maxAge: COOKIE_MAX_AGE })
-  const isFirstVisit = cookieLocale.value == null
+  const userSettings = useUserSettings()
 
-  if (process.client && isFirstVisit) {
-    const userLang = (navigator.language || 'en-US').toLowerCase()
-    // cause vue-i18n not explicit export LocaleObject type
-    const supportLocales = unref(locales) as { code: string }[]
-    const lang = supportLocales.find(locale => userLang.startsWith(locale.code.toLowerCase()))?.code
-      || supportLocales.find(locale => userLang.startsWith(locale.code.split('-')[0]))?.code
-    cookieLocale.value = lang || 'en-US'
+  if (process.server) {
+    const headers = useRequestHeaders()
+
+    let lang = cookieLocale.value
+    if (!lang || !supportLanguages.includes(lang)) {
+      // first visit
+      if (headers['accept-language']) {
+        // detect language from header
+        const userLanguages = headers['accept-language'].split(',').map(lang => lang.split(';')[0].toLowerCase())
+        lang = matchLanguages(supportLanguages, userLanguages) || DEFAULT_LANGUAGE
+      }
+      else {
+        lang = DEFAULT_LANGUAGE
+      }
+    }
+    userSettings.value.language = cookieLocale.value = lang
+
+    if (lang !== i18n.locale)
+      await setLocale(cookieLocale.value)
+
+    return
   }
 
-  if (cookieLocale.value && cookieLocale.value !== i18n.locale)
-    await setLocale(cookieLocale.value)
+  // could be null if browser don't accept cookie
+  if (!cookieLocale.value || !supportLanguages.includes(cookieLocale.value))
+    cookieLocale.value = DEFAULT_LANGUAGE
+  userSettings.value.language = cookieLocale.value
 
-  if (process.client) {
-    watchEffect(() => {
-      cookieLocale.value = i18n.locale
-    })
-  }
+  watch(() => userSettings.value.language, (lang) => {
+    if (lang !== cookieLocale.value)
+      cookieLocale.value = lang
+    if (lang !== i18n.locale)
+      setLocale(lang)
+  }, { immediate: true })
 })
diff --git a/tests/language.test.ts b/tests/language.test.ts
new file mode 100644
index 00000000..d2dffa2a
--- /dev/null
+++ b/tests/language.test.ts
@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest'
+import { matchLanguages } from '../utils/language'
+
+describe('language', () => {
+  it('match language', () => {
+    expect(matchLanguages(['zh-CN', 'zh-TW'], ['zh'])).toMatchInlineSnapshot('"zh-CN"')
+    expect(matchLanguages(['zh-CN', 'zh-TW'], ['en'])).toMatchInlineSnapshot('null')
+
+    expect(matchLanguages(['zh-CN', 'zh-TW', 'en-US'], ['zh', 'en'])).toMatchInlineSnapshot('"zh-CN"')
+    expect(matchLanguages(['zh-CN', 'zh-TW', 'en-US'], ['en', 'zh-CN'])).toMatchInlineSnapshot('"en-US"')
+    expect(matchLanguages(['zh-CN', 'zh-TW', 'en-US'], ['zh-TW', 'en'])).toMatchInlineSnapshot('"zh-TW"')
+
+    expect(matchLanguages(['zh-TW', 'en-US'], ['zh-CN', 'en-GB'])).toMatchInlineSnapshot('"zh-TW"')
+    expect(matchLanguages(['zh-TW', 'en-GB'], ['ja-JP', 'zh-CN'])).toMatchInlineSnapshot('"zh-TW"')
+
+    expect(matchLanguages(['zh-TW'], ['zh-tw'])).toMatchInlineSnapshot('"zh-TW"')
+  })
+})
diff --git a/types/index.ts b/types/index.ts
index 42e044d8..4d89faf5 100644
--- a/types/index.ts
+++ b/types/index.ts
@@ -74,6 +74,3 @@ export interface BuildInfo {
   branch: string
   env: 'preview' | 'canary' | 'dev' | 'release'
 }
-
-export type FontSize = 'xs' | 'sm' | 'md' | 'lg' | 'xl'
-export type ColorMode = 'light' | 'dark'
diff --git a/utils/language.ts b/utils/language.ts
new file mode 100644
index 00000000..ab53882a
--- /dev/null
+++ b/utils/language.ts
@@ -0,0 +1,16 @@
+export function matchLanguages(languages: string[], acceptLanguages: string[]): string | null {
+  {
+    const lang = acceptLanguages.map(userLang => languages.find(lang => lang.startsWith(userLang))).filter(v => !!v)[0]
+    if (lang)
+      return lang
+  }
+
+  const lang = acceptLanguages.map((userLang) => {
+    userLang = userLang.split('-')[0]!
+    return languages.find(lang => lang.startsWith(userLang))
+  }).filter(v => !!v)[0]
+  if (lang)
+    return lang
+
+  return null
+}