diff --git a/web/storyforge-web-v4/assets/app.js b/web/storyforge-web-v4/assets/app.js
index 498100f..e89ed6b 100644
--- a/web/storyforge-web-v4/assets/app.js
+++ b/web/storyforge-web-v4/assets/app.js
@@ -1475,11 +1475,13 @@ function syncOneLinerRunPolling() {
 
 function openOneLinerPanel() {
   ensureOneLinerUi();
+  document.body.classList.add("oneliner-open");
   document.querySelector(".oneliner-backdrop")?.classList.remove("hidden");
   syncOneLinerRunPolling();
 }
 
 function closeOneLinerPanel() {
+  document.body.classList.remove("oneliner-open");
   document.querySelector(".oneliner-backdrop")?.classList.add("hidden");
   clearOneLinerRunPollTimer();
 }
diff --git a/web/storyforge-web-v4/assets/styles.css b/web/storyforge-web-v4/assets/styles.css
index 0c8b871..87d0c2a 100644
--- a/web/storyforge-web-v4/assets/styles.css
+++ b/web/storyforge-web-v4/assets/styles.css
@@ -1255,6 +1255,13 @@ select {
   box-shadow: var(--shadow);
   color: var(--text);
   cursor: pointer;
+  transition: transform 160ms ease, opacity 160ms ease;
+}
+
+.oneliner-open .oneliner-fab {
+  opacity: 0;
+  pointer-events: none;
+  transform: translateY(16px) scale(0.96);
 }
 
 .oneliner-fab-mark {
diff --git a/web/storyforge-web-v4/tests/workbench-pages.test.mjs b/web/storyforge-web-v4/tests/workbench-pages.test.mjs
index b98bc26..700eeb6 100644
--- a/web/storyforge-web-v4/tests/workbench-pages.test.mjs
+++ b/web/storyforge-web-v4/tests/workbench-pages.test.mjs
@@ -97,7 +97,10 @@ test("mobile shell removes duplicated desktop topbar and collapses the main agen
 
 test("mobile action sheets and oneliner runtime behave like bottom sheets", () => {
   assert.match(APP, /class="sheet-handle"/);
+  assert.match(APP, /document\.body\.classList\.add\("oneliner-open"\)/);
+  assert.match(APP, /document\.body\.classList\.remove\("oneliner-open"\)/);
   assert.match(CSS, /\.sheet-handle\s*\{/);
+  assert.match(CSS, /\.oneliner-open \.oneliner-fab\s*\{[\s\S]*opacity:\s*0/);
   assert.match(CSS, /@media \(max-width: 760px\)[\s\S]*\.auth-modal,\s*[\s\S]*\.action-modal,\s*[\s\S]*\.oneliner-panel\s*\{[\s\S]*border-radius:\s*24px 24px 0 0/);
   assert.match(CSS, /@media \(max-width: 760px\)[\s\S]*\.auth-actions\s*\{[\s\S]*position:\s*sticky/);
   assert.match(CSS, /@media \(max-width: 760px\)[\s\S]*\.oneliner-composer\s*\{[\s\S]*position:\s*sticky/);