diff --git a/src/gui/components/_legacy.py b/src/gui/components/_legacy.py
index c5e1393..fe5a581 100644
--- a/src/gui/components/_legacy.py
+++ b/src/gui/components/_legacy.py
@@ -629,12 +629,20 @@ def render_sticky_footer() -> None:
         """
 <style>
 [data-testid="stAppViewBlockContainer"] {
-    /* Reserve just enough room for the fixed footer overlay (min-height
-       32px + 0.25rem * 2 padding ≈ 2rem). Anything larger leaves a
-       visible white gap above the footer that the user sees as a
-       "white bar" between content and the Help/Close row — actually
-       just ``.stApp``'s solid-white background showing through. */
+    /* Reserve room for the fixed footer overlay (footer min-height
+       32px + 0.25rem * 2 padding ≈ 2rem). */
     padding-bottom: 2rem !important;
+    /* Stretch the container to at least viewport height so its own
+       background fills the area between the last piece of content
+       and the fixed footer overlay — otherwise ``.stApp``'s solid
+       white background shows through that gap and reads as a
+       horizontal "white bar". ``.stApp`` carries ``zoom: 0.85`` so
+       100vh in this layout renders at 85% visually; divide by 0.85
+       to span the full visible viewport. The footer itself is fixed
+       and lives outside ``.stApp`` (mounted on ``<body>``), so it's
+       not affected by the zoom and overlays normally. */
+    min-height: calc(100vh / 0.85) !important;
+    box-sizing: border-box !important;
 }
 #datatools-sticky-footer {
     position: fixed !important;
