iOS focus-zoom prevention — input font-size floor @ 16px ; JS fallback strengthened

Belt-and-suspenders for the iOS Safari auto-zoom-on-input quirk: Mobile Safari zooms the viewport when an `<input>`/`<textarea>`/`<select>` is focused & its computed font-size < 16px, and never zooms back out on blur. Two layers ; PRIMARY — SCSS prevention: new `input, textarea, select, [contenteditable] { font-size: unquote("max(16px, 1em)") }` in core.scss (Sass can't reconcile px/em units in compile-time max() so unquote() passes the CSS max() through verbatim — modern browsers handle natively). 1em inherits parent, max() floors at 16. ALSO floored `.form-control-lg` in _base.scss — was `font-size: 1.125rem`, which at rem=14 (small portrait, clamp(14px, 2.4vmin, 22px) hits its floor) computes to 15.75px → **0.25px** under iOS's 16px threshold → the "ever so slightly" zoom on New Game + New Post applets the user reported (both use `.form-control.form-control-lg`, specificity 0,2,0 beats my element-level 0,0,1 rule). Floor: `unquote("max(16px, 1.125rem)")` ; SECONDARY — JS fallback in base.html: rewritten from `setAttribute('content', ...)` toggle to full meta-element remove+re-add, which modern iOS handles more reliably than attribute mutations on the existing meta. Triggers on document-level `focusout` (bubbles natively, no capture-phase needed) for `input/textarea/select`; injects fresh viewport meta w. `maximum-scale=1.0, user-scalable=no` for 300ms (iOS reads as zoom violation → snaps to 1:1), then swaps back to the cached base content so pinch-zoom remains available elsewhere ; user observed horizontal scrollbar appearing when the page zoomed — that's the symptom the user actually cared about (broken layout, not aesthetic zoom). w. SCSS floor in place the zoom shouldn't trigger to begin with; the JS is purely for inputs that slip through (future custom controls, shadow DOM, etc.) ; iOS-specific behavior — Selenium+Firefox doesn't replicate the auto-zoom so no FT layer added. Verified by user manual iPhone test (post-fix retest pending after force-refresh)

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/static_src/scss/_base.scss

@@ -159,7 +159,11 @@ body {
             &.form-control-lg {
                 --_pad-v: 0.75rem;
                 padding: var(--_pad-v) 1rem;
-                font-size: 1.125rem;
+                // 1.125rem at rem=14 (small portrait clamp floor) is 15.75px
+                // — just under iOS Safari's 16px auto-zoom threshold. Floor
+                // at 16px to prevent the focus-zoom; native CSS max() handles
+                // the unit mix Sass can't reconcile at compile time.
+                font-size: unquote("max(16px, 1.125rem)");
             }
 
             &.is-invalid ~ .invalid-feedback {

src/static_src/scss/core.scss

@@ -23,4 +23,11 @@ select,
 [contenteditable] {
     user-select: text;
     touch-action: auto;
+    // iOS Safari auto-zooms when focusing a form field whose computed font-size
+    // is < 16px. At rem=14 (small portrait viewports w. clamp(14,2.4vmin,22))
+    // a 1rem input is 14px → triggers zoom. `max(16px, 1em)` enforces the 16px
+    // floor while still inheriting larger sizes from parent contexts when set.
+    // unquote() keeps Sass from trying to evaluate the px/em compare at compile
+    // time (it can't reconcile units); CSS max() handles it natively at runtime.
+    font-size: unquote("max(16px, 1em)");
 }

src/templates/core/base.html

@@ -101,17 +101,31 @@
 
         // iOS Safari auto-zooms when focusing an <input>/<textarea>/<select>
         // whose font-size is < 16px, and does NOT auto-zoom back out on blur.
-        // Briefly toggling maximum-scale=1.0 on the viewport meta forces iOS to
-        // reset to 1:1; reverting after 100ms restores the default content so
-        // users can still pinch-zoom manually elsewhere on the page.
+        // Belt-and-suspenders: primary prevention is the global `font-size:
+        // max(16px, 1em)` rule in core.scss; this JS is a fallback for inputs
+        // that slip through (custom controls, shadow DOM, etc.). Modern iOS
+        // doesn't reliably react to a simple `setAttribute('content', ...)`
+        // tweak on the existing meta — removing and re-appending the meta
+        // element entirely is more dependable.
         (function () {
-            var vp = document.querySelector('meta[name="viewport"]');
-            if (!vp) return;
-            var base = vp.getAttribute('content');
+            var origMeta = document.querySelector('meta[name="viewport"]');
+            if (!origMeta) return;
+            var baseContent = origMeta.getAttribute('content');
             document.addEventListener('focusout', function (e) {
                 if (!e.target.matches || !e.target.matches('input, textarea, select')) return;
-                vp.setAttribute('content', base + ', maximum-scale=1.0');
-                setTimeout(function () { vp.setAttribute('content', base); }, 100);
+                var oldMeta = document.querySelector('meta[name="viewport"]');
+                if (oldMeta) oldMeta.remove();
+                var snapMeta = document.createElement('meta');
+                snapMeta.setAttribute('name', 'viewport');
+                snapMeta.setAttribute('content', baseContent + ', maximum-scale=1.0, user-scalable=no');
+                document.head.appendChild(snapMeta);
+                setTimeout(function () {
+                    snapMeta.remove();
+                    var revertMeta = document.createElement('meta');
+                    revertMeta.setAttribute('name', 'viewport');
+                    revertMeta.setAttribute('content', baseContent);
+                    document.head.appendChild(revertMeta);
+                }, 300);
             });
         }());
         </script>