diff --git src/wp-content/themes/twentyseventeen/assets/js/global.js src/wp-content/themes/twentyseventeen/assets/js/global.js
index fa29a19..7d03c74 100644
--- src/wp-content/themes/twentyseventeen/assets/js/global.js
+++ src/wp-content/themes/twentyseventeen/assets/js/global.js
@@ -148,6 +148,27 @@
 		return 'http://www.w3.org/2000/svg' === ( 'undefined' !== typeof SVGRect && div.firstChild && div.firstChild.namespaceURI );
 	}
 
+	/*
+	 * Test if background-attachment: fixed is supported.
+	 * @link http://stackoverflow.com/questions/14115080/detect-support-for-background-attachment-fixed
+	 */
+	function supportsFixedBackground() {
+		var el = document.createElement('div'),
+			isSupported;
+
+		try {
+			if ( ! ( 'backgroundAttachment' in el.style ) ) {
+				return false;
+			}
+			el.style.backgroundAttachment = 'fixed';
+			isSupported = ( 'fixed' === el.style.backgroundAttachment );
+			return isSupported;
+		}
+		catch (e) {
+			return false;
+		}
+	}
+
 	// Fire on document ready.
 	$( document ).ready( function() {
 
@@ -184,6 +205,10 @@
 		if ( true === supportsInlineSVG() ) {
 			document.documentElement.className = document.documentElement.className.replace( /(\s*)no-svg(\s*)/, '$1svg$2' );
 		}
+
+		if ( true === supportsFixedBackground() ) {
+			document.documentElement.className += ' background-fixed';
+		}
 	});
 
 	// If navigation menu is present on page, adjust it on scroll and screen resize.
diff --git src/wp-content/themes/twentyseventeen/style.css src/wp-content/themes/twentyseventeen/style.css
index 6e8e998..4f8391c 100644
--- src/wp-content/themes/twentyseventeen/style.css
+++ src/wp-content/themes/twentyseventeen/style.css
@@ -4006,9 +4006,8 @@ object {
 	}
 }
 
-@media screen and ( min-width: 85.45em ) {
-
-	.panel-image {
+@media screen and ( min-width: 55em ) {
+	.background-fixed .panel-image {
 		background-attachment: fixed;
 	}
 }