diff --git a/website/public/shell.css b/website/public/shell.css
index c20dc4f..6d98eb3 100644
--- a/website/public/shell.css
+++ b/website/public/shell.css
@@ -406,8 +406,26 @@ body.rstack-sidebar-open #toolbar {
   #app {
     padding-top: 0;
   }
+  /* Canvas on mobile: header/tab-row are sticky (in-flow), so body must
+     become a flex column to prevent the 100vh #app from overflowing. */
+  body:has(#app.canvas-layout) {
+    height: 100dvh;
+    overflow: hidden;
+    overscroll-behavior: none;
+    display: flex;
+    flex-direction: column;
+  }
+  body:has(#app.canvas-layout) .rstack-header {
+    flex-shrink: 0;
+  }
+  body:has(#app.canvas-layout) .rstack-tab-row {
+    flex-shrink: 0;
+  }
   #app.canvas-layout {
     padding-top: 0;
+    height: auto;
+    flex: 1;
+    min-height: 0;
   }
   .rspace-iframe-wrap {
     position: relative;