diff --git a/muxplex/frontend/app.js b/muxplex/frontend/app.js
index ea3bb55..c7ee62c 100644
--- a/muxplex/frontend/app.js
+++ b/muxplex/frontend/app.js
@@ -1324,6 +1324,51 @@ function showNewSessionInput(btn) {
   input.focus();
 }
 
+/**
+ * Show a fixed-position input overlay for creating a new session from the mobile FAB.
+ * Unlike showNewSessionInput (which inserts inline into btn.parentNode), this renders
+ * a fixed-position overlay appended directly to document.body — ensuring it is always
+ * visible on mobile regardless of body/view overflow:hidden constraints.
+ */
+function showFabSessionInput() {
+  const fab = $('new-session-fab');
+
+  const overlay = document.createElement('div');
+  overlay.className = 'fab-input-overlay';
+
+  const input = document.createElement('input');
+  input.type = 'text';
+  input.className = 'new-session-input';
+  input.placeholder = 'Session name\u2026';
+  input.autocomplete = 'off';
+  input.spellcheck = false;
+
+  overlay.appendChild(input);
+
+  function cleanup() {
+    if (overlay.parentNode) overlay.parentNode.removeChild(overlay);
+    if (fab) fab.style.display = '';
+  }
+
+  input.addEventListener('keydown', function(e) {
+    if (e.key === 'Enter') {
+      const name = input.value.trim();
+      cleanup();
+      if (name) createNewSession(name);
+    } else if (e.key === 'Escape') {
+      cleanup();
+    }
+  });
+
+  input.addEventListener('blur', function() {
+    setTimeout(cleanup, 150);
+  });
+
+  if (fab) fab.style.display = 'none';
+  document.body.appendChild(overlay);
+  input.focus();
+}
+
 /**
  * Create a new tmux session via POST /api/sessions.
  * Shows a toast with the created session name, calls pollSessions() to refresh,
@@ -1357,7 +1402,7 @@ function bindStaticEventListeners() {
   var sidebarNewSessionBtn = $('sidebar-new-session-btn');
   if (sidebarNewSessionBtn) on(sidebarNewSessionBtn, 'click', function() { showNewSessionInput(sidebarNewSessionBtn); });
   var newSessionFab = $('new-session-fab');
-  if (newSessionFab) on(newSessionFab, 'click', function() { showNewSessionInput(newSessionFab); });
+  if (newSessionFab) on(newSessionFab, 'click', showFabSessionInput);
   on($('sidebar-toggle-btn'), 'click', toggleSidebar);
   on($('sidebar-collapse-btn'), 'click', toggleSidebar);
   bindSidebarClickAway();
@@ -1583,6 +1628,7 @@ if (typeof module !== 'undefined' && module.exports) {
     patchServerSetting,
     // Header + button with inline name input
     showNewSessionInput,
+    showFabSessionInput,
     createNewSession,
     // Test-only helpers
     _setCurrentSessions,
diff --git a/muxplex/frontend/style.css b/muxplex/frontend/style.css
index 1ad9f3f..01636a2 100644
--- a/muxplex/frontend/style.css
+++ b/muxplex/frontend/style.css
@@ -821,6 +821,10 @@ body {
   .session-sidebar {
     transition: none;
   }
+
+  .new-session-fab:active {
+    transform: none;
+  }
 }
 
 /* ============================================================
@@ -1222,13 +1226,27 @@ body {
   cursor: pointer;
   z-index: 100;
   box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
-  transition: transform 150ms ease, box-shadow 150ms ease;
+  transition: transform 150ms ease;
 }
 
 .new-session-fab:active {
   transform: scale(0.95);
 }
 
+.new-session-fab:focus-visible {
+  outline: 2px solid var(--accent);
+  outline-offset: 2px;
+}
+
+/* Fixed-position input overlay triggered by mobile FAB —
+   appended to body so position:fixed escapes overflow:hidden on views */
+.fab-input-overlay {
+  position: fixed;
+  bottom: 80px;
+  right: 16px;
+  z-index: 200;
+}
+
 /* ============================================================
    Responsive overlay sidebar at <960px
    ============================================================ */
diff --git a/muxplex/tests/test_frontend_js.py b/muxplex/tests/test_frontend_js.py
index 6b10007..c78c04e 100644
--- a/muxplex/tests/test_frontend_js.py
+++ b/muxplex/tests/test_frontend_js.py
@@ -1858,3 +1858,73 @@ def test_js_fab_exported() -> None:
     assert "showNewSessionInput" in _JS, (
         "showNewSessionInput must exist in app.js (used by FAB click handler)"
     )
+
+
+# ============================================================
+# Mobile FAB — dedicated fixed-position input (quality fix)
+# ============================================================
+
+
+def test_js_show_fab_session_input_exists() -> None:
+    """showFabSessionInput function must exist in app.js (dedicated FAB input overlay)."""
+    assert "function showFabSessionInput" in _JS, (
+        "showFabSessionInput must be defined in app.js — "
+        "FAB needs a fixed-position overlay, not inline body insertion"
+    )
+
+
+def test_js_show_fab_session_input_appends_to_body() -> None:
+    """showFabSessionInput must append the overlay to document.body (fixed positioning)."""
+    match = re.search(
+        r"function showFabSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\nasync function |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showFabSessionInput function not found"
+    body = match.group(1)
+    assert "document.body" in body, (
+        "showFabSessionInput must append to document.body "
+        "(fixed-position overlays must be direct body children to escape overflow:hidden)"
+    )
+
+
+def test_js_show_fab_session_input_handles_enter() -> None:
+    """showFabSessionInput must call createNewSession on Enter key."""
+    match = re.search(
+        r"function showFabSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\nasync function |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showFabSessionInput function not found"
+    body = match.group(1)
+    assert "Enter" in body, "showFabSessionInput must handle Enter key"
+    assert "createNewSession" in body, (
+        "showFabSessionInput must call createNewSession on Enter"
+    )
+
+
+def test_js_show_fab_session_input_handles_escape() -> None:
+    """showFabSessionInput must handle Escape key to cancel."""
+    match = re.search(
+        r"function showFabSessionInput\s*\(\s*\)\s*\{(.*?)(?=\nfunction |\nasync function |\n// )",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "showFabSessionInput function not found"
+    body = match.group(1)
+    assert "Escape" in body, "showFabSessionInput must handle Escape key"
+
+
+def test_js_fab_click_calls_show_fab_session_input() -> None:
+    """bindStaticEventListeners must bind FAB click to showFabSessionInput (not inline body insert)."""
+    match = re.search(
+        r"function bindStaticEventListeners\s*\(\s*\)\s*\{(.*?)\n\}",
+        _JS,
+        re.DOTALL,
+    )
+    assert match, "bindStaticEventListeners function not found"
+    body = match.group(1)
+    assert "showFabSessionInput" in body, (
+        "bindStaticEventListeners must call showFabSessionInput for FAB click — "
+        "the old showNewSessionInput(fab) inserts into body which is clipped by overflow:hidden"
+    )