post header bg scroll if safari

package.json

@@ -13,7 +13,7 @@
     "@babel/preset-env": "^7.9.6"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "build": "/usr/local/bin/hugo"
   },
   "repository": {
     "type": "git",

themes/desem-swift-theme/assets/js/redzuurdesem.js

@@ -1,5 +1,7 @@
 (function() {
 
+	// from swift theme: sandwich
+	// ******
 	function modifyClass(el, targetClass) {
 		if (isObj(el) && targetClass) {
 		  const elClass = el.classList;
@@ -33,8 +35,7 @@
 		  elClass.contains(targetClass) ? false : elClass.add(targetClass);
 		}
 	}
-	// from swift theme: sandwich
-	// ******
+
 	(function() {
 		let bar = 'nav_bar-wrap';
 		let navBar = elem(`.${bar}`);
@@ -71,7 +72,6 @@
 
 	})();	
 
-
 	(function postsPager(){
 		const pager = elem('.pagination');
 		if (pager) {
@@ -90,7 +90,9 @@
 		  });
 		}
 	})();
+	// ******
 
+	(function() {
 		var fbposts = document.querySelector('#fbposts');
 		function whoops(error) {
 			console.log(error);
@@ -119,6 +121,18 @@
 				whoops(e);
 			}
 		}
+		if(fbposts && window.fbtoken) {
+			window.fbAsyncInit = getRedZuurdesemFacebookFeed;
+		}
+	})()
+
+	function fromFixedToScrollForSafari() {
+		const isSafari = /^((?!chrome|android).)*safari/i.test(navigator.userAgent);
+		const header = document.querySelector('.post_header');
+		if(isSafari) {
+			header.style.backgroundAttachment = 'scroll';
+		}
+	}
 
 	function fbCommunityHeaderify() {
 		var elem = document.querySelector('#fb-community-header');
@@ -155,9 +169,7 @@
         elem.innerHTML = '<div class="fb-page" data-width="' + vw + '" data-href="https://www.facebook.com/redzuurdesem" data-hide-cover="false" data-tabs="timeline,messages" data-show-facepile="false"></div>';
 	}
 
-	if(fbposts && window.fbtoken) {
-		window.fbAsyncInit = getRedZuurdesemFacebookFeed;
-	}
 	fbCommunityHeaderify();
 	fbCommunityContainer();
+	fromFixedToScrollForSafari();
 })()

themes/desem-swift-theme/assets/sass/_posts.sass

@@ -65,8 +65,7 @@
     background-size: cover
     background-repeat: no-repeat
     background-position: center    
-    
-    background-attachment: fixed;
+    background-attachment: fixed
 
     position: relative
     height: 48vh