diff --git a/.changeset/thick-mice-tan.md b/.changeset/thick-mice-tan.md
new file mode 100644
index 000000000..f3d913a73
--- /dev/null
+++ b/.changeset/thick-mice-tan.md
@@ -0,0 +1,5 @@
+---
+'@getodk/web-forms': patch
+---
+
+Prevent background scroll and browser zooming in full-screen map
diff --git a/packages/web-forms/src/assets/styles/style.scss b/packages/web-forms/src/assets/styles/style.scss
index 689b731ce..03a2ba38f 100644
--- a/packages/web-forms/src/assets/styles/style.scss
+++ b/packages/web-forms/src/assets/styles/style.scss
@@ -80,6 +80,9 @@
 	/* Overlays like modals, popups, or dialogs above form content */
 	--odk-z-index-overlay: 100;
 
+	/* Floating feedback button */
+	--odk-z-index-feedback-button: 900;
+
 	/* Critical UI elements (e.g., loading spinners, toast notifications) */
 	--odk-z-index-topmost: 1000;
 }
diff --git a/packages/web-forms/src/components/common/map/MapBlock.vue b/packages/web-forms/src/components/common/map/MapBlock.vue
index eecdd4925..3fb06aca7 100644
--- a/packages/web-forms/src/components/common/map/MapBlock.vue
+++ b/packages/web-forms/src/components/common/map/MapBlock.vue
@@ -262,7 +262,7 @@ const saveAdvancedPanelCoords = (newCoords: Coordinate) => {
 	border: 1px solid var(--odk-border-color);
 	border-radius: var(--odk-radius);
 	overflow: hidden;
-	// Fixes iPhone select issues on map
+	// iPhone - fixes select issues on map
 	-webkit-user-select: none;
 	user-select: none;
 	-webkit-touch-callout: none;
@@ -295,18 +295,31 @@ const saveAdvancedPanelCoords = (newCoords: Coordinate) => {
 }
 
 .map-container.map-full-screen {
+	position: fixed;
+	inset: 0;
 	display: flex;
 	flex-direction: column;
-	justify-content: flex-start;
-	position: fixed;
-	top: 0;
-	left: 0;
-	height: 100vh;
 	width: 100vw;
+	height: 100dvh;
 	z-index: var(--odk-z-index-topmost);
+	background: var(--odk-base-background-color);
+	border-radius: 0;
+
+	// Prevent background scroll-chaining
+	overscroll-behavior: none;
+	// Hand touch gestures (zoom/pan) exclusively to the map engine
+	touch-action: none;
 
 	.map-block {
-		flex-grow: 2;
+		flex: 1 1 0;
+		width: 100%;
+		min-height: 0;
+		height: auto;
+	}
+
+	:deep(.map-status-bar),
+	:deep(.advanced-panel) {
+		flex-shrink: 0;
 	}
 }
 
diff --git a/packages/web-forms/src/demo/FeedbackButton.vue b/packages/web-forms/src/demo/FeedbackButton.vue
index b3cc43bf7..0ebfc3858 100644
--- a/packages/web-forms/src/demo/FeedbackButton.vue
+++ b/packages/web-forms/src/demo/FeedbackButton.vue
@@ -41,7 +41,7 @@ const surveyLink = computed(() => {
 	right: 0;
 	bottom: 150px;
 	height: 4rem;
-	z-index: var(--odk-z-index-topmost);
+	z-index: var(--odk-z-index-feedback-button);
 	border-top-left-radius: var(--odk-radius);
 	border-top-right-radius: var(--odk-radius);
 	text-align: center;