use flexbox for app navbar in dev center

src/dev-center/css/style.css

@@ -855,7 +855,11 @@ ol li:before {
     float:right; margin-bottom: 10px;
 }
 .edit-app-navbar{
-    overflow: hidden; margin-bottom: 60px; margin-top: 20px;
+    overflow: hidden; 
+    margin-bottom: 60px; 
+    margin-top: 20px;
+    display: flex;
+    align-items: center;
 }
 .app-title{
     margin-top:0px; 

src/dev-center/js/dev-center.js

@@ -440,7 +440,7 @@ function generate_edit_app_section(app) {
     let h = ``;
     h += `
         <div class="edit-app-navbar">
-            <div style="float:left; min-width: 700px;">
+            <div style="flex-grow:1;">
                 <img class="app-icon" data-uid="${html_encode(app.uid)}" src="${html_encode(!app.icon ? './img/app.svg' : app.icon)}">
                 <h3 class="app-title" data-uid="${html_encode(app.uid)}">${html_encode(app.title)}</h3>
                 <div style="margin-top: 4px; margin-bottom: 4px;">