diff --git a/src/components/CommandPalette.jsx b/src/components/CommandPalette.jsx
index 7e5fc43..a1a4015 100644
--- a/src/components/CommandPalette.jsx
+++ b/src/components/CommandPalette.jsx
@@ -94,7 +94,7 @@ export default function CommandPalette({ onClose }) {
   if (authUser === null && !authServerDown) return null; // the sign-in screen has nothing to search
   let lastGroup = null;
   return (
-    <div style={themeVars(readerTheme)} className="fixed inset-0 z-[90] flex items-start justify-center bg-black/40 px-3 pt-[12vh] font-sans" onMouseDown={(e) => { if (e.target === e.currentTarget) onClose(); }}>
+    <div style={themeVars(readerTheme)} className="fixed inset-0 z-[90] flex items-start justify-center bg-black/40 px-3 pt-[12dvh] font-sans" onMouseDown={(e) => { if (e.target === e.currentTarget) onClose(); }}>
       <div role="dialog" aria-modal="true" aria-label="Search and go to" className="w-full max-w-xl overflow-hidden rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] text-[var(--r-text)] shadow-2xl">
         <div className="flex items-center gap-2 border-b border-[var(--r-line)] px-4 py-3">
           <span className="text-[var(--r-sub)]"><SearchIcon /></span>
@@ -107,7 +107,7 @@ export default function CommandPalette({ onClose }) {
           />
           <kbd className="hidden rounded border border-[var(--r-line)] px-1.5 py-0.5 text-[10px] text-[var(--r-sub)] sm:block">esc</kbd>
         </div>
-        <ul id="palette-list" role="listbox" ref={listRef} className="max-h-[50vh] overflow-y-auto p-2">
+        <ul id="palette-list" role="listbox" ref={listRef} className="max-h-[50dvh] overflow-y-auto p-2">
           {items.length === 0 && <li className="px-3 py-6 text-center text-sm text-[var(--r-sub)]">Nothing found. Try a book and chapter, like “romans 8”.</li>}
           {items.map((item, i) => {
             const header = item.group !== lastGroup ? item.group : null;
diff --git a/src/components/PresentMode.jsx b/src/components/PresentMode.jsx
index 6e59a4f..1e2008e 100644
--- a/src/components/PresentMode.jsx
+++ b/src/components/PresentMode.jsx
@@ -106,14 +106,14 @@ export default function PresentMode({ title, subtitle = '', mode, script = '', t
       </div>
 
       {mode === 'script' ? (
-        <div ref={scroller} className="min-h-0 flex-1 overflow-y-auto px-[6vw] py-[8vh]" style={{ scrollBehavior: 'auto' }}>
+        <div ref={scroller} className="min-h-0 flex-1 overflow-y-auto px-[6vw] py-[8dvh]" style={{ scrollBehavior: 'auto' }}>
           {script.trim()
-            ? <div className="mx-auto max-w-[46em] whitespace-pre-wrap font-serif" style={{ fontSize, lineHeight: 1.5 }}>{script}<div style={{ height: '50vh' }} aria-hidden="true" /></div>
+            ? <div className="mx-auto max-w-[46em] whitespace-pre-wrap font-serif" style={{ fontSize, lineHeight: 1.5 }}>{script}<div style={{ height: '50dvh' }} aria-hidden="true" /></div>
             : <p className="mt-20 text-center text-lg opacity-70">There’s no script to present yet. Write one on the Script page.</p>}
         </div>
       ) : (
         <div className="flex min-h-0 flex-1 flex-col">
-          <div className="min-h-0 flex-1 overflow-y-auto px-[6vw] py-[6vh]">
+          <div className="min-h-0 flex-1 overflow-y-auto px-[6vw] py-[6dvh]">
             {step ? (
               <div className="mx-auto max-w-[46em] font-serif" style={{ fontSize, lineHeight: 1.4 }}>
                 <p className="font-sans text-[0.4em] uppercase tracking-[0.16em] opacity-60">{step.kind ? `${step.kind} · ` : ''}Point {index + 1} of {steps.length}{step.minutes ? ` · ${step.minutes} min` : ''}</p>
diff --git a/src/components/ShortcutsHelp.jsx b/src/components/ShortcutsHelp.jsx
index f7f9df2..3037830 100644
--- a/src/components/ShortcutsHelp.jsx
+++ b/src/components/ShortcutsHelp.jsx
@@ -53,7 +53,7 @@ export default function ShortcutsHelp({ onClose }) {
 
   return (
     <div style={themeVars(readerTheme)} className="fixed inset-0 z-[90] flex items-center justify-center bg-black/40 px-3 font-sans" onMouseDown={(e) => { if (e.target === e.currentTarget) onClose(); }}>
-      <div role="dialog" aria-modal="true" aria-label="Keyboard shortcuts" className="max-h-[80vh] w-full max-w-sm overflow-y-auto rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] p-5 text-[var(--r-text)] shadow-2xl">
+      <div role="dialog" aria-modal="true" aria-label="Keyboard shortcuts" className="max-h-[80dvh] w-full max-w-sm overflow-y-auto rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] p-5 text-[var(--r-text)] shadow-2xl">
         <div className="mb-3 flex items-center justify-between">
           <h2 className="text-base font-medium">Keyboard shortcuts</h2>
           <button ref={closeRef} type="button" onClick={onClose} className="rounded-lg px-2 py-1 text-sm text-[var(--r-sub)] hover:bg-black/5">Close</button>
diff --git a/src/components/plans/PlanDetailSheet.jsx b/src/components/plans/PlanDetailSheet.jsx
index 010e17c..a2aed2c 100644
--- a/src/components/plans/PlanDetailSheet.jsx
+++ b/src/components/plans/PlanDetailSheet.jsx
@@ -44,7 +44,7 @@ function ActiveBody({ plan, progress, onClose, actions }) {
           </div>
         </div>
       )}
-      <div className="max-h-[38vh] overflow-y-auto rounded-xl border border-[var(--r-line)]">
+      <div className="max-h-[38dvh] overflow-y-auto rounded-xl border border-[var(--r-line)]">
         {schedule.map((refs, i) => {
           const done = progress.completedDays.includes(i);
           return (
diff --git a/src/components/reader/Sheet.jsx b/src/components/reader/Sheet.jsx
index e64d76f..8d966fc 100644
--- a/src/components/reader/Sheet.jsx
+++ b/src/components/reader/Sheet.jsx
@@ -46,7 +46,7 @@ export default function Sheet({ open, onClose, title, label, headerRight, modal
         aria-modal={modal ? 'true' : undefined}
         aria-label={typeof title === 'string' ? title : label}
         tabIndex={-1}
-        className={`fixed inset-x-0 bottom-0 z-50 flex max-h-[72vh] flex-col rounded-t-2xl focus:outline-none border-t border-[var(--r-line)] bg-[var(--r-bar)] text-[var(--r-text)] font-sans ${
+        className={`fixed inset-x-0 bottom-0 z-50 flex max-h-[72dvh] flex-col rounded-t-2xl focus:outline-none border-t border-[var(--r-line)] bg-[var(--r-bar)] text-[var(--r-text)] font-sans ${
           pane ? 'lg:inset-x-auto lg:bottom-0 lg:right-0 lg:top-12 lg:max-h-none lg:w-[var(--reader-pane,24rem)] lg:rounded-none lg:border-l lg:border-t-0' : 'sm:left-1/2 sm:right-auto sm:w-[36rem] sm:-translate-x-1/2'
         }`}
       >
diff --git a/src/components/study/PageShell.jsx b/src/components/study/PageShell.jsx
index 39290b0..32b2168 100644
--- a/src/components/study/PageShell.jsx
+++ b/src/components/study/PageShell.jsx
@@ -70,7 +70,7 @@ export default function PageShell({ title, onBack, actions, active = null, maxWi
       <a href="#content" className="skip-link">Skip to content</a>
       <header className="safe-top sticky top-0 z-30 border-b border-[var(--r-line)] bg-[var(--r-bar)]">
         <div className={`mx-auto flex h-12 ${maxWidth} items-center gap-2 px-3 sm:gap-4 sm:px-4`}>
-          <button type="button" onClick={goHome} className="flex shrink-0 items-center gap-2" aria-label="Bible Study home">
+          <button type="button" onClick={goHome} className="-m-2 flex shrink-0 items-center gap-2 p-2" aria-label="Bible Study home">
             <img src="/logo.svg" alt="" className="h-6 w-6" />
             <span className="hidden text-sm font-medium sm:inline">Bible Study</span>
           </button>
diff --git a/src/components/study/SuggestWordsSheet.jsx b/src/components/study/SuggestWordsSheet.jsx
index ca10523..fdd13d0 100644
--- a/src/components/study/SuggestWordsSheet.jsx
+++ b/src/components/study/SuggestWordsSheet.jsx
@@ -16,7 +16,7 @@ export default function SuggestWordsSheet({ wordStudy }) {
         <button type="button" onClick={() => setSuggestSelection(new Set())} className="text-[var(--r-accent)] hover:underline">Select none</button>
         <span className="ml-auto text-[var(--r-sub)]">{n} selected</span>
       </div>
-      <ul className="max-h-[40vh] divide-y divide-[var(--r-line)] overflow-y-auto rounded-xl border border-[var(--r-line)] px-3">
+      <ul className="max-h-[40dvh] divide-y divide-[var(--r-line)] overflow-y-auto rounded-xl border border-[var(--r-line)] px-3">
         {suggestModal.words.map((w) => (
           <li key={w.strongKey}>
             <label className="flex cursor-pointer items-center gap-3 py-2.5">
diff --git a/src/index.css b/src/index.css
index 15084b8..da7754f 100644
--- a/src/index.css
+++ b/src/index.css
@@ -31,6 +31,51 @@ select {
   font: inherit;
 }
 
+/* iPhone and iPad: don't inflate text when the phone is turned sideways, no grey flash on tap, and no
+   double-tap-to-zoom delay on controls. */
+html {
+  -webkit-text-size-adjust: 100%;
+  text-size-adjust: 100%;
+  -webkit-tap-highlight-color: transparent;
+}
+button,
+a,
+select,
+summary,
+label,
+input,
+[role='button'],
+[role='tab'],
+[role='option'],
+[role='menuitem'] {
+  touch-action: manipulation;
+}
+
+/* iOS Safari zooms the whole page when a text field under 16px gets focus (and doesn't zoom back).
+   On touch screens, text fields are at least 16px. */
+@media (pointer: coarse) {
+  input:not([type='checkbox']):not([type='radio']):not([type='range']):not([type='color']):not([type='file']):not([type='button']):not([type='submit']),
+  select:not([data-keep-size]),
+  textarea:not([data-keep-size]) {
+    font-size: max(16px, 1em);
+  }
+
+  /* Small text links and buttons (no padding of their own) get a finger-sized height. */
+  :is(button, a).text-xs:not([class^='p-'], [class^='py-'], [class*=' p-'], [class*=' py-']) {
+    padding-block: 0.55rem;
+  }
+
+  /* Small pill buttons (tags, chips) keep their look but get a bigger area to tap. */
+  :where(button.rounded-full) {
+    position: relative;
+  }
+  :where(button.rounded-full)::after {
+    content: '';
+    position: absolute;
+    inset: -7px -3px;
+  }
+}
+
 /* Top bars leave room for the status bar / notch when the app is installed or full-screen
    (env() is 0 in an ordinary browser tab). */
 .safe-top {
diff --git a/src/pages/ReaderPage.jsx b/src/pages/ReaderPage.jsx
index 2110356..d35224a 100644
--- a/src/pages/ReaderPage.jsx
+++ b/src/pages/ReaderPage.jsx
@@ -21,6 +21,7 @@ import NavigatorSheet from '../components/reader/NavigatorSheet.jsx';
 import SettingsSheet from '../components/reader/SettingsSheet.jsx';
 import CompareSheet from '../components/reader/CompareSheet.jsx';
 import SearchSheet from '../components/reader/SearchSheet.jsx';
+import { swipeAllowedFrom } from '../utils/swipe.js';
 import CrossRefMap from '../components/reader/CrossRefMap.jsx';
 import { useIqAvailable } from '../hooks/useIq.js';
 import MarksSheet from '../components/reader/MarksSheet.jsx';
@@ -259,12 +260,13 @@ export default function ReaderPage() {
 
   // Swipe left/right to change chapter
   const handleTouchStart = (e) => {
-    if (readerDrawMode) return;
+    if (readerDrawMode || !swipeAllowedFrom(e.target)) { swipeTouchRef.current = null; return; }
     const t = e.changedTouches[0];
     swipeTouchRef.current = { x: t.clientX, y: t.clientY };
   };
   const handleTouchEnd = (e) => {
     if (readerDrawMode || !swipeTouchRef.current) return;
+    if (!window.getSelection()?.isCollapsed) { swipeTouchRef.current = null; return; } // dragging a text selection
     const t = e.changedTouches[0];
     const dx = t.clientX - swipeTouchRef.current.x;
     const dy = t.clientY - swipeTouchRef.current.y;
@@ -529,7 +531,7 @@ export default function ReaderPage() {
         {/* Draw mode: scripture beside a notebook canvas */}
         {readerDrawMode && (
           <div className="mx-auto flex max-w-7xl flex-col items-start gap-4 px-4 py-4 pb-8 sm:flex-row">
-            <div className="w-full rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] p-4 font-serif text-sm leading-relaxed sm:sticky sm:top-16 sm:max-h-[80vh] sm:w-72 sm:shrink-0 sm:overflow-y-auto"
+            <div className="w-full rounded-2xl border border-[var(--r-line)] bg-[var(--r-bar)] p-4 font-serif text-sm leading-relaxed sm:sticky sm:top-16 sm:max-h-[80dvh] sm:w-72 sm:shrink-0 sm:overflow-y-auto"
                  onPointerUp={handleSelectionEnd}>
               <div className="mb-3">
                 <span className="font-medium">{readerBook?.name} {readerChapter}</span>
diff --git a/src/pages/SetupPage.jsx b/src/pages/SetupPage.jsx
index fe8ac40..2781681 100644
--- a/src/pages/SetupPage.jsx
+++ b/src/pages/SetupPage.jsx
@@ -113,7 +113,7 @@ export default function SetupPage() {
                   </div>
                   <input type="text" value={b.verseSearch} onChange={(e) => b.setVerseSearch(e.target.value)} placeholder="Search verses in this chapter…"
                     className="mb-3 w-full rounded-xl border border-[var(--r-line)] bg-[var(--r-bg)] px-3 py-2 text-sm text-[var(--r-text)] focus:outline-none focus:ring-2 focus:ring-[var(--r-line)]" />
-                  <div data-testid="verse-list" className="max-h-[68vh] overflow-y-auto rounded-xl bg-[var(--r-bg)] px-3 py-3 font-serif text-[1.02rem] leading-[1.8]">
+                  <div data-testid="verse-list" className="max-h-[68dvh] overflow-y-auto rounded-xl bg-[var(--r-bg)] px-3 py-3 font-serif text-[1.02rem] leading-[1.8]">
                     {activeChapter.verses
                       .filter((v) => v.text.toLowerCase().includes(b.verseSearch.trim().toLowerCase()))
                       .map((verse) => {
@@ -181,7 +181,7 @@ export default function SetupPage() {
                       <button type="button" onClick={() => b.splitAfterVerse(lastVerse)} className={smallBtn} title="Make one chunk from the last chunk to the end of the chapter">Chunk the rest</button>
                     )}
                   </div>
-                  <div className="max-h-[42vh] space-y-2 overflow-y-auto">
+                  <div className="max-h-[42dvh] space-y-2 overflow-y-auto">
                     {activeChapter.chunks.length === 0 ? (
                       <p className="rounded-xl border border-dashed border-[var(--r-line)] p-3 text-sm text-[var(--r-sub)]">No chunks yet. Click between verses, or suggest them from the headings.</p>
                     ) : activeChapter.chunks.map((chunk, index) => (
diff --git a/src/utils/swipe.js b/src/utils/swipe.js
new file mode 100644
index 0000000..c7160b2
--- /dev/null
+++ b/src/utils/swipe.js
@@ -0,0 +1,12 @@
+// Swiping sideways on the reading page turns the chapter. It shouldn't when the finger is on something that has its
+// own sideways gesture: a sheet, a form field, or a row that scrolls sideways.
+const OWN_GESTURE = 'input, textarea, select, [role="dialog"], [role="slider"], [data-no-swipe]';
+
+export function swipeAllowedFrom(target) {
+  if (!target?.closest) return true;
+  if (target.closest(OWN_GESTURE)) return false;
+  for (let el = target; el && el !== document.body; el = el.parentElement) {
+    if (el.scrollWidth > el.clientWidth + 1 && /(auto|scroll)/.test(getComputedStyle(el).overflowX)) return false;
+  }
+  return true;
+}
diff --git a/src/utils/swipe.test.js b/src/utils/swipe.test.js
new file mode 100644
index 0000000..97b4d3c
--- /dev/null
+++ b/src/utils/swipe.test.js
@@ -0,0 +1,26 @@
+import { afterEach, expect, test } from 'vitest';
+import { swipeAllowedFrom } from './swipe.js';
+
+afterEach(() => { document.body.innerHTML = ''; });
+const mount = (html) => { document.body.innerHTML = html; return document.body.firstElementChild; };
+
+test('swiping on plain text is allowed', () => {
+  const root = mount('<div><p id="t">verse</p></div>');
+  expect(swipeAllowedFrom(root.querySelector('#t'))).toBe(true);
+  expect(swipeAllowedFrom(null)).toBe(true);
+});
+
+test('sheets, fields and sliders keep their own sideways gestures', () => {
+  const root = mount('<div><div role="dialog"><button id="a">x</button></div><input id="b"><div data-no-swipe><span id="c"></span></div></div>');
+  expect(swipeAllowedFrom(root.querySelector('#a'))).toBe(false);
+  expect(swipeAllowedFrom(root.querySelector('#b'))).toBe(false);
+  expect(swipeAllowedFrom(root.querySelector('#c'))).toBe(false);
+});
+
+test('a row that scrolls sideways is left alone', () => {
+  const root = mount('<div id="row" style="overflow-x:auto"><span id="s"></span></div>');
+  const row = root;
+  Object.defineProperty(row, 'scrollWidth', { value: 500, configurable: true });
+  Object.defineProperty(row, 'clientWidth', { value: 200, configurable: true });
+  expect(swipeAllowedFrom(row.querySelector('#s'))).toBe(false);
+});