Elegant Business: Add a utility css class for spacer block

elegant-business/sass/blocks/_blocks.scss

@@ -680,10 +680,15 @@
 		}
 	}
 
-	//! Separator
+	//! Spacer
 	.wp-block-spacer {
-		margin-bottom: $size__vertical-spacing-unit;
-		margin-top: $size__vertical-spacing-unit;
+		&.desktop-only {
+			display: none;
+
+			@include media(tablet) {
+				display: block;
+			}
+		}
 	}
 
 	//! Twitter Embed

elegant-business/style-rtl.css

@@ -4105,9 +4105,14 @@ body.page .main-navigation {
   display: none;
 }
 
-.entry .entry-content .wp-block-spacer {
-  margin-bottom: 32px;
-  margin-top: 32px;
+.entry .entry-content .wp-block-spacer.desktop-only {
+  display: none;
+}
+
+@media only screen and (min-width: 768px) {
+  .entry .entry-content .wp-block-spacer.desktop-only {
+    display: block;
+  }
 }
 
 .entry .entry-content .wp-block-embed-twitter {

elegant-business/style.css

@@ -4117,9 +4117,14 @@ body.page .main-navigation {
   display: none;
 }
 
-.entry .entry-content .wp-block-spacer {
-  margin-bottom: 32px;
-  margin-top: 32px;
+.entry .entry-content .wp-block-spacer.desktop-only {
+  display: none;
+}
+
+@media only screen and (min-width: 768px) {
+  .entry .entry-content .wp-block-spacer.desktop-only {
+    display: block;
+  }
 }
 
 .entry .entry-content .wp-block-embed-twitter {