diff --git a/README.md b/README.md
index 3d28fde..46c37f1 100644
--- a/README.md
+++ b/README.md
@@ -777,6 +777,10 @@ Things I chose while building, with the reasoning:
     device, uses Chrome's deferred `beforeinstallprompt` for a one-tap install where available, and
     stays reachable from Settings. It is mounted in the root layout, so it can appear over any
     screen — including the key gate — without blocking the page underneath.
+30. **Phones don't zoom, and mobile fields are 16px.** The viewport sets `maximum-scale=1` /
+    `user-scalable=no` for an app-like feel, and a mobile-only rule keeps every input and textarea at
+    16px so iOS Safari's focus auto-zoom never fires (iOS ignores `user-scalable=no` for that).
+    Desktop keeps the designed 12–14px field sizes.
 14. **`gpt-oss:120b` does all content work — but it cannot read images** (`this model does not
     support image input`), so `VISION_MODEL` has to stay a multimodal model (`gemma4:31b-cloud`).
     Text-only inputs — pasted text, PDFs with a text layer, DOCX/PPTX/ODT — never touch the vision
diff --git a/app/globals.css b/app/globals.css
index 7315bcb..97dd60b 100644
--- a/app/globals.css
+++ b/app/globals.css
@@ -550,6 +550,18 @@ body {
 }
 }
 
+/* Mobile form fields ----------------------------------------------------- */
+/* iOS Safari zooms the whole page when a focused field's text is under 16px
+   (it ignores user-scalable=no for that). Deliberately unlayered so it wins
+   over the per-component Tailwind sizes, and only on phone-sized screens. */
+@media (max-width: 639px) {
+  input:not([type="checkbox"]):not([type="radio"]):not([type="range"]),
+  textarea,
+  select {
+    font-size: 16px;
+  }
+}
+
 /* Reduced motion --------------------------------------------------------- */
 @media (prefers-reduced-motion: reduce) {
   *,
diff --git a/app/layout.tsx b/app/layout.tsx
index 970bb6c..7705146 100644
--- a/app/layout.tsx
+++ b/app/layout.tsx
@@ -41,7 +41,11 @@ export const metadata: Metadata = {
 export const viewport: Viewport = {
   width: "device-width",
   initialScale: 1,
-  maximumScale: 5,
+  // Phones: no pinch/double-tap zoom (the app-like feel). The input font-size
+  // rule in globals.css is what actually stops iOS Safari's focus auto-zoom,
+  // which ignores user-scalable=no.
+  maximumScale: 1,
+  userScalable: false,
   viewportFit: "cover",
   themeColor: [
     { media: "(prefers-color-scheme: light)", color: "#f8fafc" },