feat: give the camera its own layout so no control needs a scroll

src/presentation/App.ts

@@ -17,43 +17,51 @@ declare const __APP_VERSION__: string;
 
 export function renderApp(root: HTMLElement): void {
   root.innerHTML = `
-    <header class="masthead">
-      <img class="masthead__mark" src="${import.meta.env.BASE_URL}favicon.svg" alt="" width="44" height="44" />
-      <div>
-        <h1 class="masthead__title">Esku</h1>
-        <p class="masthead__tagline">Lengua de signos a texto, sin conexión</p>
+    <!--
+      Everything needed to actually read signs lives in one viewport-tall column, so that
+      turning the camera on never means scrolling to reach a control. Secondary panels stay
+      below it rather than behind a sheet: the diagnostics panel in particular is read *while*
+      the camera runs, and the sticky action bar keeps the controls reachable down there.
+    -->
+    <div class="shell" id="shell">
+      <header class="masthead">
+        <img class="masthead__mark" src="${import.meta.env.BASE_URL}favicon.svg" alt="" width="44" height="44" />
+        <div>
+          <h1 class="masthead__title">Esku</h1>
+          <p class="masthead__tagline">Lengua de signos a texto, sin conexión</p>
+        </div>
+      </header>
+
+      <div class="stage">
+        <video id="video" class="stage__video" playsinline muted></video>
+        <canvas id="overlay" class="stage__overlay" aria-hidden="true"></canvas>
+        <p class="stage__placeholder" id="placeholder">
+          La cámara se activa al empezar.<br />El vídeo no se graba ni sale del dispositivo.
+        </p>
+        <p class="stage__hint" id="hint" hidden></p>
+
+        <ul class="parts" id="parts">
+          ${PART_ORDER.map(
+            (part) => `
+            <li class="part" data-part="${part}">
+              <span class="part__dot" style="--part: ${PART_COLOURS[part]}"></span>
+              ${PART_LABELS[part]}
+            </li>`,
+          ).join('')}
+        </ul>
       </div>
-    </header>
 
-    <div class="stage">
-      <video id="video" class="stage__video" playsinline muted></video>
-      <canvas id="overlay" class="stage__overlay" aria-hidden="true"></canvas>
-      <p class="stage__placeholder" id="placeholder">
-        La cámara se activa al empezar.<br />El vídeo no se graba ni sale del dispositivo.
-      </p>
-      <p class="stage__hint" id="hint" hidden></p>
-    </div>
+      <div class="transcript" id="transcript" aria-live="polite"></div>
 
-    <ul class="parts" id="parts">
-      ${PART_ORDER.map(
-        (part) => `
-        <li class="part" data-part="${part}">
-          <span class="part__dot" style="--part: ${PART_COLOURS[part]}"></span>
-          ${PART_LABELS[part]}
-        </li>`,
-      ).join('')}
-    </ul>
-
-    <div class="transcript" id="transcript" aria-live="polite"></div>
-
-    <div class="actions">
-      <button class="button" id="toggle" type="button">Empezar a leer</button>
-      <button class="button button--quiet" id="undo" type="button">Borrar último</button>
-      <button class="button button--quiet" id="clear" type="button">Limpiar</button>
-      <button class="button button--quiet" id="flip" type="button">Cámara trasera</button>
-    </div>
+      <p class="status" id="status" role="status"></p>
 
-    <p class="status" id="status" role="status"></p>
+      <div class="actions actions--bar">
+        <button class="button" id="toggle" type="button">Empezar a leer</button>
+        <button class="button button--quiet" id="undo" type="button">Borrar último</button>
+        <button class="button button--quiet" id="clear" type="button">Limpiar</button>
+        <button class="button button--quiet" id="flip" type="button">Cámara trasera</button>
+      </div>
+    </div>
 
     <div id="teach"></div>
     <div id="storage"></div>
@@ -125,6 +133,7 @@ export function renderApp(root: HTMLElement): void {
     if (running) {
       recognize.stop();
       running = false;
+      root.classList.remove('is-running');
       toggle.textContent = 'Empezar a leer';
       placeholder.hidden = false;
       hint.hidden = true;
@@ -152,6 +161,9 @@ export function renderApp(root: HTMLElement): void {
         diagnostics.update(update.diagnostics);
       });
       running = true;
+      // Camera mode: the masthead folds away, the video takes the height the fixed 3/4 ratio
+      // used to claim regardless of device, and the controls pin to the bottom of the screen.
+      root.classList.add('is-running');
       placeholder.hidden = true;
       video.classList.add('is-live');
       overlayCanvas.classList.add('is-live');
@@ -161,6 +173,8 @@ export function renderApp(root: HTMLElement): void {
         error instanceof CameraUnavailableError
           ? 'No hay cámara o se denegó el permiso. Revísalo en los ajustes del navegador.'
           : 'No se pudo iniciar el reconocimiento.';
+      // The camera never opened, so the layout must not be left claiming it did.
+      root.classList.remove('is-running');
       // Without the real cause in the console this is undiagnosable from a bug report.
       console.error(error);
     } finally {

src/presentation/styles/global.css

@@ -65,11 +65,56 @@ body {
 }
 
 #app {
+  --pad-top: 20px;
+  --pad-bottom: calc(40px + env(safe-area-inset-bottom));
+  /* Height of the pinned action bar in camera mode, reserved so nothing hides beneath it. */
+  --bar: 72px;
+
   max-width: 560px;
   margin: 0 auto;
-  padding: 20px 16px 40px;
   /* Keep the transcript clear of the iOS home indicator when installed. */
-  padding-bottom: calc(40px + env(safe-area-inset-bottom));
+  padding: var(--pad-top) 16px var(--pad-bottom);
+}
+
+/*
+ * Camera mode.
+ *
+ * With the camera on this stops being a page and becomes a tool: everything needed to read
+ * signs occupies exactly one viewport, so no control is ever a scroll away. Measured before
+ * this existed, the primary block alone came to ~813 px on a 390x844 phone — the masthead and
+ * a hard-coded 3/4 stage between them claimed more than half the screen.
+ */
+#app.is-running .shell {
+  display: flex;
+  flex-direction: column;
+  gap: var(--gap);
+  /* dvh, not vh: mobile browsers shrink the viewport as their chrome collapses, and vh keeps
+     measuring the tall version, pushing the action bar under the address bar. */
+  min-height: calc(100vh - var(--pad-top) - var(--pad-bottom));
+  min-height: calc(100dvh - var(--pad-top) - var(--pad-bottom));
+}
+
+/* Name and tagline are for someone deciding whether to use the app, not someone using it. */
+#app.is-running .masthead {
+  display: none;
+}
+
+/* The one element that should absorb whatever space the device has. */
+#app.is-running .stage {
+  aspect-ratio: auto;
+  flex: 1;
+  min-height: 0;
+  margin-bottom: 0;
+}
+
+#app.is-running .transcript,
+#app.is-running .status {
+  margin: 0;
+}
+
+/* Room for the pinned bar, which is out of flow and would otherwise cover the last panel. */
+#app.is-running {
+  padding-bottom: calc(var(--pad-bottom) + var(--bar));
 }
 
 .masthead {
@@ -190,6 +235,28 @@ body {
   line-height: 1.2;
 }
 
+.actions--bar {
+  margin-top: 0;
+}
+
+/*
+ * Pinned rather than merely sticky: the diagnostics panel is read *while* the camera runs,
+ * and scrolling down to it must not strand the user without a stop button.
+ */
+#app.is-running .actions--bar {
+  position: fixed;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  z-index: 20;
+  margin: 0 auto;
+  max-width: 560px;
+  padding: 10px 16px calc(10px + env(safe-area-inset-bottom));
+  background: color-mix(in srgb, var(--bg) 92%, transparent);
+  backdrop-filter: blur(12px);
+  border-top: 1px solid var(--border);
+}
+
 .status {
   color: var(--text-muted);
   font-size: 0.85rem;
@@ -376,13 +443,34 @@ body {
 
 /* One chip per tracked body part. Colour identifies the part, fill says whether it is
    currently being seen — so "it is not working" becomes "it cannot see your face". */
+/*
+ * Over the video rather than beside it. These say what the camera is currently tracking, so
+ * they belong on the camera — and off it they said nothing while costing a whole row.
+ */
 .parts {
+  position: absolute;
+  left: 10px;
+  right: 10px;
+  top: 10px;
   display: flex;
   flex-wrap: wrap;
   gap: 8px;
   list-style: none;
-  margin: 0 0 var(--gap);
+  margin: 0;
   padding: 0;
+  opacity: 0;
+  transition: opacity 0.25s ease;
+  pointer-events: none;
+}
+
+#app.is-running .parts {
+  opacity: 1;
+}
+
+/* Legible over whatever the camera happens to be pointing at. */
+#app.is-running .part {
+  background: color-mix(in srgb, var(--bg) 72%, transparent);
+  backdrop-filter: blur(8px);
 }
 
 .part {