--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Navigation.java	Wed Apr 24 10:20:25 2019 -0400
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/Navigation.java	Wed Apr 24 11:26:44 2019 -0700
@@ -429,7 +429,7 @@
                 }
                 if (!listContents.isEmpty()) {
                     Content li = HtmlTree.LI(contents.summaryLabel);
-                    li.add(Contents.SPACE);
+                    li.add(Entity.NO_BREAK_SPACE);
                     tree.add(li);
                     addListToNav(listContents, tree);
                 }
@@ -461,7 +461,7 @@
                 }
                 if (!listContents.isEmpty()) {
                     Content li = HtmlTree.LI(contents.moduleSubNavLabel);
-                    li.add(Contents.SPACE);
+                    li.add(Entity.NO_BREAK_SPACE);
                     tree.add(li);
                     addListToNav(listContents, tree);
                 }
@@ -665,7 +665,7 @@
                 }
                 if (!listContents.isEmpty()) {
                     Content li = HtmlTree.LI(contents.detailLabel);
-                    li.add(Contents.SPACE);
+                    li.add(Entity.NO_BREAK_SPACE);
                     tree.add(li);
                     addListToNav(listContents, tree);
                 }
@@ -801,9 +801,9 @@
         int count = 0;
         for (Content liContent : listContents) {
             if (count < listContents.size() - 1) {
-                liContent.add(Contents.SPACE);
+                liContent.add(Entity.NO_BREAK_SPACE);
                 liContent.add("|");
-                liContent.add(Contents.SPACE);
+                liContent.add(Entity.NO_BREAK_SPACE);
             }
             tree.add(liContent);
             count++;
@@ -1005,7 +1005,7 @@
                 fixedNavDiv.add(queue.poll());
                 fixedNavDiv.add(Position.TOP.endOfNav());
                 tree.add(fixedNavDiv);
-                HtmlTree paddingDiv = HtmlTree.DIV(HtmlStyle.navPadding, Contents.SPACE);
+                HtmlTree paddingDiv = HtmlTree.DIV(HtmlStyle.navPadding, Entity.NO_BREAK_SPACE);
                 tree.add(paddingDiv);
                 addFixedNavScript(tree);
             } else {