diff --git a/app/src/debug/AndroidManifest.xml b/app/src/debug/AndroidManifest.xml
index 2f48a82a56..4bf8bf1e6d 100644
--- a/app/src/debug/AndroidManifest.xml
+++ b/app/src/debug/AndroidManifest.xml
@@ -29,7 +29,8 @@
             android:theme="@style/Theme.AppCompat.Translucent" />
 
         <activity android:name=".autofill.AutofillSearchActivity"
-            android:exported="false" />
+            android:exported="false"
+            android:theme="@style/DialogActivityTheme" />
 
         <service
             android:name=".autofill.AutofillService"
diff --git a/app/src/main/java/org/mozilla/fenix/autofill/AutofillSearchActivity.kt b/app/src/main/java/org/mozilla/fenix/autofill/AutofillSearchActivity.kt
index 32b070f5b1..d72ef135bd 100644
--- a/app/src/main/java/org/mozilla/fenix/autofill/AutofillSearchActivity.kt
+++ b/app/src/main/java/org/mozilla/fenix/autofill/AutofillSearchActivity.kt
@@ -5,6 +5,8 @@
 package org.mozilla.fenix.autofill
 
 import android.os.Build
+import android.os.Bundle
+import android.view.ViewGroup
 import androidx.annotation.RequiresApi
 import mozilla.components.feature.autofill.AutofillConfiguration
 import mozilla.components.feature.autofill.ui.AbstractAutofillSearchActivity
@@ -17,4 +19,15 @@ import org.mozilla.fenix.ext.components
 @RequiresApi(Build.VERSION_CODES.O)
 class AutofillSearchActivity : AbstractAutofillSearchActivity() {
     override val configuration: AutofillConfiguration by lazy { components.autofillConfiguration }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        // To avoid the dialog constantly resizing horizontally while typing, let's always use
+        // the full width of the screen for the dialog.
+        window.setLayout(
+            ViewGroup.LayoutParams.MATCH_PARENT,
+            ViewGroup.LayoutParams.WRAP_CONTENT
+        )
+    }
 }
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index c86cacc07d..3398c0e122 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -116,6 +116,33 @@
         <item name="tabCounterTintColor">?primaryText</item>
     </style>
 
+    <!-- A theme derived from the normal activity theme, but to look and behave like a dialog -->
+    <style name="DialogActivityTheme" parent="NormalTheme">
+        <item name="android:windowElevation">16dp</item>
+        <item name="android:colorBackground">?attr/colorBackgroundFloating</item>
+        <item name="android:colorBackgroundCacheHint">@null</item>
+        <item name="android:windowFrame">@null</item>
+        <item name="android:windowTitleStyle">@style/RtlOverlay.DialogWindowTitle.AppCompat</item>
+        <item name="android:windowTitleBackgroundStyle">@style/Base.DialogWindowTitleBackground.AppCompat</item>
+        <item name="android:windowIsFloating">true</item>
+        <item name="android:backgroundDimEnabled">true</item>
+        <item name="android:windowContentOverlay">@null</item>
+        <item name="android:windowAnimationStyle">@style/Animation.AppCompat.Dialog</item>
+        <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
+
+        <item name="windowActionBar">false</item>
+        <item name="windowActionModeOverlay">true</item>
+
+        <item name="listPreferredItemPaddingLeft">24dip</item>
+        <item name="listPreferredItemPaddingRight">24dip</item>
+
+        <item name="android:listDivider">@null</item>
+
+        <item name="android:buttonBarStyle">@style/Widget.AppCompat.ButtonBar.AlertDialog</item>
+        <item name="android:borderlessButtonStyle">@style/Widget.AppCompat.Button.Borderless</item>
+        <item name="android:windowCloseOnTouchOutside">true</item>
+    </style>
+
     <style name="NormalTheme" parent="NormalThemeBase" />
 
     <style name="BaseDialogStyle" parent="Theme.MaterialComponents.Dialog.Alert">