diff --git a/services/web/frontend/stylesheets/pages/project-list-lumiere.scss b/services/web/frontend/stylesheets/pages/project-list-lumiere.scss
index 9a437efdf1..438767acda 100644
--- a/services/web/frontend/stylesheets/pages/project-list-lumiere.scss
+++ b/services/web/frontend/stylesheets/pages/project-list-lumiere.scss
@@ -893,6 +893,13 @@ $lum-noise: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' wi
 
   @media (max-width: 767px) {
 
+    // The sidebar (min-width:200px) sits in a flex row with the content area,
+    // making the page ~575px wide on a 375px phone. Hide it — the filter pills
+    // in the mobile toolbar already replace all its functionality.
+    .project-list-sidebar-wrapper-react {
+      display: none !important;
+    }
+
     // Stack the header vertically so nothing overflows the viewport width.
     // Without this, lumiere-header-actions (flex-shrink:0) forces the flex
     // container wider than the screen.