diff --git a/src/assets/styles/app-shell.css b/src/assets/styles/app-shell.css
index b9a235a..ca2ddcf 100644
--- a/src/assets/styles/app-shell.css
+++ b/src/assets/styles/app-shell.css
@@ -104,36 +104,60 @@
   }
 }
 
-/* ── Guest pages (login, checkout) ── */
+/* ── Guest pages (login, register, checkout) — all breakpoints ── */
+.app-shell--no-nav {
+  align-items: center;
+  justify-content: center;
+  padding: 16px;
+  background: var(--color-page-background);
+}
+
+.app-shell--no-nav .app-layout {
+  max-width: var(--form-max-width);
+  width: 100%;
+  height: auto;
+  max-height: calc(100dvh - 32px);
+}
+
+.app-shell--no-nav .app-frame {
+  max-width: var(--form-max-width);
+  width: 100%;
+  height: auto;
+  max-height: calc(100dvh - 32px);
+  border-radius: var(--radius-lg);
+  box-shadow: var(--shadow-frame);
+  background: var(--color-surface);
+}
+
+.app-shell--no-nav .app-content {
+  padding-inline: var(--page-padding);
+}
+
+.app-shell--no-nav .page {
+  background: transparent;
+}
+
+.app-shell--no-nav.app-shell--wide .app-layout,
+.app-shell--no-nav.app-shell--wide .app-frame {
+  max-width: min(var(--content-max-width), calc(100vw - 32px));
+}
+
+.app-shell--no-nav.app-shell--wide .app-frame {
+  background: var(--color-bg);
+}
+
 @media (min-width: 768px) {
   .app-shell--no-nav {
-    align-items: center;
-    justify-content: center;
     padding: 24px;
-    background: var(--color-page-background);
-  }
-
-  .app-shell--no-nav .app-layout {
-    max-width: var(--form-max-width);
-    width: 100%;
-    height: auto;
-    max-height: calc(100dvh - 48px);
   }
 
+  .app-shell--no-nav .app-layout,
   .app-shell--no-nav .app-frame {
-    max-width: var(--form-max-width);
-    border-radius: var(--radius-lg);
-    box-shadow: var(--shadow-frame);
     max-height: calc(100dvh - 48px);
-    background: var(--color-surface);
   }
 
   .app-shell--no-nav.app-shell--wide .app-layout,
   .app-shell--no-nav.app-shell--wide .app-frame {
     max-width: min(var(--content-max-width), calc(100vw - 48px));
   }
-
-  .app-shell--no-nav.app-shell--wide .app-frame {
-    background: var(--color-bg);
-  }
 }
diff --git a/src/assets/styles/main.css b/src/assets/styles/main.css
index 1caef9b..a0ca911 100644
--- a/src/assets/styles/main.css
+++ b/src/assets/styles/main.css
@@ -204,6 +204,13 @@ input[type='number'] {
   color: var(--color-text);
 }
 
+.auth-page .card {
+  background: transparent;
+  border: none;
+  box-shadow: none;
+  padding-inline: 0;
+}
+
 .card + .card {
   margin-top: var(--page-gap);
 }
diff --git a/src/components/ui/AuthThemeToggle.vue b/src/components/ui/AuthThemeToggle.vue
new file mode 100644
index 0000000..5478ed9
--- /dev/null
+++ b/src/components/ui/AuthThemeToggle.vue
@@ -0,0 +1,59 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+import { storeToRefs } from 'pinia'
+import BasicIcon from '@/components/BasicPacks/BasicIcon.vue'
+import { useThemeStore } from '@/stores/theme'
+
+const themeStore = useThemeStore()
+const { isDark } = storeToRefs(themeStore)
+
+const themeIcon = computed(() =>
+  isDark.value ? 'vuesax-linear:sun-1' : 'vuesax-linear:moon',
+)
+const themeLabel = computed(() =>
+  isDark.value ? 'تغییر به تم روشن' : 'تغییر به تم تاریک',
+)
+</script>
+
+<template>
+  <button
+    type="button"
+    class="auth-theme-toggle"
+    :aria-label="themeLabel"
+    :title="themeLabel"
+    @click="themeStore.toggleLightDark()"
+  >
+    <BasicIcon :icon="themeIcon" :size="22" :stroke-width="1.5" />
+  </button>
+</template>
+
+<style scoped>
+.auth-theme-toggle {
+  position: fixed;
+  top: calc(12px + env(safe-area-inset-top, 0px));
+  inset-inline-end: 16px;
+  z-index: 100;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 44px;
+  height: 44px;
+  padding: 0;
+  border: 1px solid var(--color-border);
+  border-radius: 12px;
+  background: var(--color-surface);
+  color: var(--color-text);
+  box-shadow: var(--shadow-sm);
+  cursor: pointer;
+  transition:
+    background-color 0.15s ease,
+    border-color 0.15s ease,
+    color 0.15s ease;
+}
+
+.auth-theme-toggle:hover {
+  border-color: var(--color-primary);
+  background: var(--color-primary-soft);
+  color: var(--color-primary);
+}
+</style>
diff --git a/src/stores/theme.ts b/src/stores/theme.ts
index 4702205..d4adbc9 100644
--- a/src/stores/theme.ts
+++ b/src/stores/theme.ts
@@ -25,10 +25,23 @@ export const useThemeStore = defineStore('theme', () => {
     preference.value = value
   }
 
+  function cyclePreference() {
+    const order: ThemePreference[] = ['light', 'dark', 'system']
+    const index = order.indexOf(preference.value)
+    preference.value = order[(index + 1) % order.length]!
+  }
+
+  /** Explicit light ↔ dark toggle (skips system). */
+  function toggleLightDark() {
+    preference.value = isDark.value ? 'light' : 'dark'
+  }
+
   return {
     preference,
     resolved,
     isDark,
     setPreference,
+    cyclePreference,
+    toggleLightDark,
   }
 })
diff --git a/src/views/auth/LoginView.vue b/src/views/auth/LoginView.vue
index 88e6633..5bd20b8 100644
--- a/src/views/auth/LoginView.vue
+++ b/src/views/auth/LoginView.vue
@@ -5,6 +5,7 @@ import { useAuthStore } from '@/stores/auth'
 import BaseInput from '@/components/ui/BaseInput.vue'
 import FormErrorBanner from '@/components/ui/FormErrorBanner.vue'
 import BaseButton from '@/components/ui/BaseButton.vue'
+import AuthThemeToggle from '@/components/ui/AuthThemeToggle.vue'
 import { normalizePhone, toPersianDigits } from '@/utils/format'
 import { validatePhone } from '@/utils/validation'
 import {
@@ -72,6 +73,8 @@ async function submit() {
 
 <template>
   <div class="page page-shell auth-page">
+    <AuthThemeToggle />
+
     <div class="page__scroll flex flex-col justify-center py-6">
       <div class="auth-header">
         <div class="text-5xl mb-3">🧵</div>
@@ -100,11 +103,16 @@ async function submit() {
         <BaseButton block type="submit" :loading="auth.loading">دریافت کد تأیید</BaseButton>
       </form>
 
-      <div class="mt-6 w-full max-w-[var(--form-max-width)]">
-        <p class="m-0 mb-2.5 text-center text-sm text-muted">حساب کاربری ندارید؟</p>
-        <RouterLink v-slot="{ navigate }" to="/register" custom>
-          <BaseButton block variant="outline" type="button" @click="navigate">ثبت‌نام</BaseButton>
-        </RouterLink>
+      <div class="mt-6 w-full max-w-[var(--form-max-width)] text-center">
+        <p class="m-0 text-sm text-muted">
+          حساب کاربری ندارید؟
+          <RouterLink
+            to="/register"
+            class="ms-1 font-bold text-primary no-underline hover:underline"
+          >
+            ثبت نام کنید
+          </RouterLink>
+        </p>
       </div>
     </div>
   </div>
diff --git a/src/views/auth/OtpView.vue b/src/views/auth/OtpView.vue
index 8fbe2db..7c08f79 100644
--- a/src/views/auth/OtpView.vue
+++ b/src/views/auth/OtpView.vue
@@ -5,6 +5,7 @@ import { useIntervalFn } from '@vueuse/core'
 import { useAuthStore } from '@/stores/auth'
 import FormErrorBanner from '@/components/ui/FormErrorBanner.vue'
 import BaseButton from '@/components/ui/BaseButton.vue'
+import AuthThemeToggle from '@/components/ui/AuthThemeToggle.vue'
 import { toPersianDigits, extractNumericString } from '@/utils/format'
 import {
   FORM_VALIDATION_SUMMARY,
@@ -209,6 +210,8 @@ onMounted(() => {
 
 <template>
   <div class="page page-shell auth-page">
+    <AuthThemeToggle />
+
     <div class="page__scroll flex flex-col justify-center py-6">
       <div class="auth-header">
         <h1 class="page-title">تأیید شماره موبایل</h1>
diff --git a/src/views/auth/RegisterView.vue b/src/views/auth/RegisterView.vue
index b2436ea..1708046 100644
--- a/src/views/auth/RegisterView.vue
+++ b/src/views/auth/RegisterView.vue
@@ -5,6 +5,7 @@ import { useAuthStore } from '@/stores/auth'
 import BaseInput from '@/components/ui/BaseInput.vue'
 import FormErrorBanner from '@/components/ui/FormErrorBanner.vue'
 import BaseButton from '@/components/ui/BaseButton.vue'
+import AuthThemeToggle from '@/components/ui/AuthThemeToggle.vue'
 import { normalizePhone } from '@/utils/format'
 import { validatePhone } from '@/utils/validation'
 import {
@@ -66,6 +67,8 @@ async function submit() {
 
 <template>
   <div class="page page-shell auth-page">
+    <AuthThemeToggle />
+
     <div class="page__scroll flex flex-col justify-center py-6">
       <div class="auth-header">
         <div class="text-5xl mb-3">🧵</div>
@@ -101,11 +104,16 @@ async function submit() {
         <BaseButton block :loading="auth.loading" @click="submit">دریافت کد تأیید</BaseButton>
       </div>
 
-      <div class="mt-6 w-full max-w-[var(--form-max-width)]">
-        <p class="m-0 mb-2.5 text-center text-sm text-muted">قبلاً ثبت‌نام کرده‌اید؟</p>
-        <RouterLink v-slot="{ navigate }" to="/login" custom>
-          <BaseButton block variant="outline" type="button" @click="navigate">ورود</BaseButton>
-        </RouterLink>
+      <div class="mt-6 w-full max-w-[var(--form-max-width)] text-center">
+        <p class="m-0 text-sm text-muted">
+          قبلاً ثبت‌نام کرده‌اید؟
+          <RouterLink
+            to="/login"
+            class="ms-1 font-bold text-primary no-underline hover:underline"
+          >
+            وارد شوید
+          </RouterLink>
+        </p>
       </div>
     </div>
   </div>