diff --git a/app/Http/Controllers/Api/LogInController.php b/app/Http/Controllers/Api/LogInController.php
index 48ef4e94..08512bd1 100644
--- a/app/Http/Controllers/Api/LogInController.php
+++ b/app/Http/Controllers/Api/LogInController.php
@@ -42,6 +42,8 @@ public function __invoke(Request $request): JsonResponse
             return response()
                 ->json([
                     'token' => $apiKey->token,
+                    'language' => Auth::user()->language,
+                    'theme' => Auth::user()->theme,
                 ]);
         } else {
             $userByEmail = User::query()
diff --git a/app/Http/Controllers/Api/SettingsController.php b/app/Http/Controllers/Api/SettingsController.php
index 644199a0..090c7bac 100644
--- a/app/Http/Controllers/Api/SettingsController.php
+++ b/app/Http/Controllers/Api/SettingsController.php
@@ -38,6 +38,10 @@ public function store(Request $request): JsonResponse
             $apiKey->user()->update(['theme' => $request->get('theme')]);
         }
 
-        return response()->json([]);
+        return response()
+            ->json([
+                'language' => $apiKey->user->language,
+                'theme' => $apiKey->user->theme,
+            ]);
     }
 }
diff --git a/resources/assets/js/prototype/components/App.vue b/resources/assets/js/prototype/components/App.vue
index 9beff603..8274faaa 100644
--- a/resources/assets/js/prototype/components/App.vue
+++ b/resources/assets/js/prototype/components/App.vue
@@ -1,5 +1,16 @@
 <script setup>
+const applyTheme = () => {
+    const dark = localStorage.getItem('theme') === 'dark';
 
+    const el = document.querySelector('html');
+
+    el.classList.add(dark ? 'dark' : 'light');
+    el.classList.remove(dark ? 'light' : 'dark');
+};
+
+applyTheme();
+
+document.addEventListener('themeChanged', () => applyTheme());
 </script>
 
 <template>
diff --git a/resources/assets/js/prototype/components/Navigation.vue b/resources/assets/js/prototype/components/Navigation.vue
index b45abf73..31a15bb2 100644
--- a/resources/assets/js/prototype/components/Navigation.vue
+++ b/resources/assets/js/prototype/components/Navigation.vue
@@ -12,26 +12,26 @@ const logOut = () => {
 </script>
 
 <template>
-    <div class="flex items-center h-16 bg-white border-b border-gray-200">
+    <div class="flex items-center h-16 bg-white dark:bg-gray-800 border-b border-gray-200 dark:border-gray-700">
         <div class="mx-auto flex-1 flex items-center justify-between max-w-5xl">
             <div class="flex space-x-4">
-                <router-link class="flex items-center py-1 px-3 text-gray-500 hover:text-black" :to="{ name: 'dashboard' }">
+                <router-link class="flex items-center py-1 px-3 text-gray-500 dark:text-gray-400 hover:text-black dark:hover:text-white" :to="{ name: 'dashboard' }">
                     <Home :size="16" />
                     <span class="ml-2 text-sm">Dashboard</span>
                 </router-link>
-                <router-link class="flex items-center py-1 px-3 text-gray-500 hover:text-black" :to="{ name: 'transactions.index' }">
+                <router-link class="flex items-center py-1 px-3 text-gray-500 dark:text-gray-400 hover:text-black dark:hover:text-white" :to="{ name: 'transactions.index' }">
                     <ArrowRightLeft :size="16" />
                     <span class="ml-2 text-sm">Transactions</span>
                 </router-link>
             </div>
             <div class="flex items-center space-x-4">
-                <router-link class="flex py-1 px-3 text-gray-500 hover:text-black" :to="{ name: 'transactions.create' }">
+                <router-link class="flex py-1 px-3 text-gray-500 dark:text-gray-400 hover:text-black dark:hover:text-white" :to="{ name: 'transactions.create' }">
                     <PlusCircle :size="20" :strokeWidth="1.6" />
                 </router-link>
-                <router-link class="flex py-1 px-3 text-gray-500 hover:text-black" :to="{ name: 'settings.preferences' }">
+                <router-link class="flex py-1 px-3 text-gray-500 dark:text-gray-400 hover:text-black dark:hover:text-white" :to="{ name: 'settings.preferences' }">
                     <Settings2 :size="16" />
                 </router-link>
-                <button class="flex py-1 px-3 text-gray-500 hover:text-black" @click="logOut()">
+                <button class="flex py-1 px-3 text-gray-500 dark:text-gray-400 hover:text-black dark:hover:text-white" @click="logOut()">
                     <LogOut :size="16" />
                 </button>
             </div>
diff --git a/resources/assets/js/prototype/screens/Dashboard.vue b/resources/assets/js/prototype/screens/Dashboard.vue
index e5d063c0..0d1d64dd 100644
--- a/resources/assets/js/prototype/screens/Dashboard.vue
+++ b/resources/assets/js/prototype/screens/Dashboard.vue
@@ -22,7 +22,7 @@ const getTimeSensitiveGreeting = () => {
         <div class="my-10 mx-auto max-w-3xl">
             <div class="flex flex-col items-center text-gray-400">
                 <Construction :size="32" :strokeWidth="1.5" />
-                <div class="mt-2 text-center text-sm text-gray-400">{{ getTimeSensitiveGreeting() }} and<br /> welcome to the prototype.</div>
+                <div class="mt-2 text-center text-sm">{{ getTimeSensitiveGreeting() }} and<br /> welcome to the prototype.</div>
             </div>
         </div>
     </div>
diff --git a/resources/assets/js/prototype/screens/Login.vue b/resources/assets/js/prototype/screens/Login.vue
index 67694694..480435fa 100644
--- a/resources/assets/js/prototype/screens/Login.vue
+++ b/resources/assets/js/prototype/screens/Login.vue
@@ -15,6 +15,10 @@ const logIn = () => {
 
             if (json.token) {
                 localStorage.setItem('api_key', json.token);
+                localStorage.setItem('theme', json.theme);
+
+                const e = new Event('themeChanged');
+                document.dispatchEvent(e);
 
                 router.push('dashboard');
             }
@@ -31,16 +35,16 @@ const logIn = () => {
 
 <template>
     <div class="flex items-center justify-center min-h-screen">
-        <div class="flex-1 max-w-sm p-5 space-y-5 bg-white border rounded-lg">
+        <div class="flex-1 max-w-sm p-5 space-y-5 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg">
             <div>
-                <label class="block mb-2 text-sm">E-mail</label>
-                <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="email" v-model="email" />
+                <label class="block mb-2 text-sm dark:text-white">E-mail</label>
+                <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="email" v-model="email" />
             </div>
             <div>
-                <label class="block mb-2 text-sm">Password</label>
-                <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="password" v-model="password" @keyup.enter="logIn" />
+                <label class="block mb-2 text-sm dark:text-white">Password</label>
+                <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="password" v-model="password" @keyup.enter="logIn" />
             </div>
-            <button class="w-full py-3 text-sm text-white bg-gray-900 rounded-lg" @click="logIn">Log in</button>
+            <button class="w-full py-3 text-sm text-white bg-gray-900 dark:bg-gray-950 rounded-lg" @click="logIn">Log in</button>
         </div>
     </div>
 </template>
diff --git a/resources/assets/js/prototype/screens/Settings/Preferences.vue b/resources/assets/js/prototype/screens/Settings/Preferences.vue
index 7f3679ed..3447b122 100644
--- a/resources/assets/js/prototype/screens/Settings/Preferences.vue
+++ b/resources/assets/js/prototype/screens/Settings/Preferences.vue
@@ -19,8 +19,13 @@ const retrieve = () => {
 const update = () => {
     axios
         .post('/api/settings', { language: language.value, theme: theme.value }, { headers: { 'api-key': localStorage.getItem('api_key') } })
-        .then(() => {
+        .then(response => {
             // Done
+
+            localStorage.setItem('theme', response.data.theme);
+
+            const e = new Event('themeChanged');
+            document.dispatchEvent(e);
         })
         .catch(() => {
             alert('Unable to save');
@@ -34,11 +39,11 @@ onMounted(() => retrieve());
     <div>
         <Navigation />
         <div class="my-10 mx-auto max-w-3xl">
-            <div class="p-5 bg-white border border-gray-200 rounded-lg">
+            <div class="p-5 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg">
                 <div class="space-y-5 max-w-xs">
                     <div>
-                        <div class="mb-2 text-sm">Language</div>
-                        <select class="px-3.5 py-2.5 w-full text-sm border border-gray-200 rounded-lg appearance-none" v-model="language" @change="update">
+                        <div class="mb-2 text-sm dark:text-white">Language</div>
+                        <select class="px-3.5 py-2.5 w-full text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg appearance-none" v-model="language" @change="update">
                             <option value="en">English</option>
                             <option value="nl">Dutch</option>
                             <option value="dk">Danish</option>
@@ -49,8 +54,8 @@ onMounted(() => retrieve());
                         </select>
                     </div>
                     <div>
-                        <div class="mb-2 text-sm">Theme</div>
-                        <select class="px-3.5 py-2.5 w-full text-sm border border-gray-200 rounded-lg appearance-none" v-model="theme" @change="update">
+                        <div class="mb-2 text-sm dark:text-white">Theme</div>
+                        <select class="px-3.5 py-2.5 w-full text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg appearance-none" v-model="theme" @change="update">
                             <option value="light">Light</option>
                             <option value="dark">Dark</option>
                         </select>
diff --git a/resources/assets/js/prototype/screens/Transactions/Create.vue b/resources/assets/js/prototype/screens/Transactions/Create.vue
index d22c1573..fba35f39 100644
--- a/resources/assets/js/prototype/screens/Transactions/Create.vue
+++ b/resources/assets/js/prototype/screens/Transactions/Create.vue
@@ -33,28 +33,28 @@ const create = () => {
     <div>
         <Navigation />
         <div class="my-10 mx-auto max-w-sm">
-            <div class="p-5 space-y-5 bg-white border border-gray-200 rounded-lg">
+            <div class="p-5 space-y-5 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg">
                 <div class="flex space-x-3">
-                    <button class="px-4 py-2.5 text-sm border border-gray-200 rounded-lg" :class="{ 'bg-gray-100': type === 'earning' }" @click="type = 'earning'">Earning</button>
-                    <button class="px-4 py-2.5 text-sm border border-gray-200 rounded-lg" :class="{ 'bg-gray-100': type === 'spending' }" @click="type = 'spending'">Spending</button>
+                    <button class="px-4 py-2.5 text-sm dark:text-white border border-gray-200 dark:border-gray-600 rounded-lg" :class="{ 'bg-gray-100 dark:bg-gray-700': type === 'earning' }" @click="type = 'earning'">Earning</button>
+                    <button class="px-4 py-2.5 text-sm dark:text-white border border-gray-200 dark:border-gray-600 rounded-lg" :class="{ 'bg-gray-100 dark:bg-gray-700': type === 'spending' }" @click="type = 'spending'">Spending</button>
                 </div>
                 <div v-if="type === 'spending'">
-                    <label class="mb-2 block text-sm">Tag</label>
-                    <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="text" value="Coming soon" disabled />
+                    <label class="mb-2 block text-sm dark:text-white">Tag</label>
+                    <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="text" value="Coming soon" disabled />
                 </div>
                 <div>
-                    <label class="mb-2 block text-sm">Date</label>
-                    <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="text" v-model="happened_on" />
+                    <label class="mb-2 block text-sm dark:text-white">Date</label>
+                    <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="text" v-model="happened_on" />
                 </div>
                 <div>
-                    <label class="mb-2 block text-sm">Description</label>
-                    <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="text" :placeholder="type === 'earning' ? 'Paycheck February' : 'Birthday present for Angela'" v-model="description" />
+                    <label class="mb-2 block text-sm dark:text-white">Description</label>
+                    <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="text" :placeholder="type === 'earning' ? 'Paycheck February' : 'Birthday present for Angela'" v-model="description" />
                 </div>
                 <div>
-                    <label class="mb-2 block text-sm">Amount</label>
-                    <input class="w-full px-3.5 py-2.5 text-sm border rounded-lg" type="text" v-model="amount" />
+                    <label class="mb-2 block text-sm dark:text-white">Amount</label>
+                    <input class="w-full px-3.5 py-2.5 text-sm dark:text-white dark:bg-gray-700 border border-gray-200 dark:border-gray-600 rounded-lg" type="text" v-model="amount" />
                 </div>
-                <button class="w-full py-3 text-sm text-white bg-gray-900 rounded-lg" @click="create()">Create</button>
+                <button class="w-full py-3 text-sm text-white bg-gray-900 dark:bg-gray-950 rounded-lg" @click="create()">Create</button>
             </div>
         </div>
     </div>
diff --git a/resources/assets/js/prototype/screens/Transactions/Index.vue b/resources/assets/js/prototype/screens/Transactions/Index.vue
index a9d174c9..56e99fae 100644
--- a/resources/assets/js/prototype/screens/Transactions/Index.vue
+++ b/resources/assets/js/prototype/screens/Transactions/Index.vue
@@ -74,13 +74,13 @@ onMounted(() => {
         <div class="max-w-3xl mx-auto my-10 space-y-10">
             <div v-for="span in spans" class="flex">
                 <div class="w-48">
-                    <div class="font-medium">{{ getMonthName(span.month) }}</div>
-                    <div class="mt-1 text-sm text-gray-500">{{ span.year }}</div>
+                    <div class="font-medium dark:text-white">{{ getMonthName(span.month) }}</div>
+                    <div class="mt-1 text-sm text-gray-500 dark:text-gray-400">{{ span.year }}</div>
                 </div>
                 <div class="flex-1">
-                    <div class="py-4 px-5 space-y-2 bg-white rounded-lg border border-gray-200">
+                    <div class="py-4 px-5 space-y-2 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg">
                         <div class="flex items-center justify-between" v-for="transaction in getTransactionsBySpan(span)">
-                            <div class="text-sm text-gray-500">{{ transaction.description }}</div>
+                            <div class="text-sm text-gray-500 dark:text-white">{{ transaction.description }}</div>
                             <div class="text-sm" :class="'text-' + (transaction.type === 'earning' ? 'green' : 'red') + '-600'">+{{ (transaction.amount / 100).toFixed(2) }}</div>
                         </div>
                     </div>
diff --git a/resources/views/prototype.blade.php b/resources/views/prototype.blade.php
index 0bac9233..0363dd28 100644
--- a/resources/views/prototype.blade.php
+++ b/resources/views/prototype.blade.php
@@ -2,8 +2,13 @@
 <html>
     <head>
         <script src="https://cdn.tailwindcss.com"></script>
+        <script>
+            tailwind.config = {
+                darkMode: 'class',
+            };
+        </script>
     </head>
-    <body class="bg-gray-50">
+    <body class="bg-gray-50 dark:bg-gray-900">
         <div id="app"></div>
         @vite('resources/assets/js/prototype/app.js')
     </body>