Animate/fade dropdown menus

templates/menu.html

-<nav class="navbar is-fixed-top" role="navigation" aria-label="main navigation" id="main-navbar">
+<nav class="navbar is-fixed-top is-boxed" role="navigation" aria-label="main navigation" id="main-navbar">
     <input type="checkbox" id="burger-toggle" role="button" class="navbar-toggle" aria-label="menu" aria-expanded="false" data-target="main-menu" />
     <div class="navbar-brand">
         <a href="{{ get_url(path="@/_index.md") }}" class="navbar-item">
@@ -16,28 +16,28 @@
         <div class="navbar-start">
             <div class="navbar-item has-dropdown is-hoverable is-mega">
                 <a href="#" class="navbar-item">Projekte</a>
-                <div class="navbar-dropdown">
+                <div class="navbar-dropdown is-boxed">
                     {% include "menu/projects.html" %}
                 </div>
             </div>
 
             <div class="navbar-item has-dropdown is-hoverable is-mega">
                 <a href="#" class="navbar-item">Informationen für…</a>
-                <div class="navbar-dropdown">
+                <div class="navbar-dropdown is-boxed">
                     {% include "menu/infos.html" %}
                 </div>
             </div>
 
             <div class="navbar-item has-dropdown is-hoverable">
                 <a href="#" class="navbar-item">Teckids-Gemeinschaft</a>
-                <div class="navbar-dropdown">
+                <div class="navbar-dropdown is-boxed">
                     {% include "menu/gemeinschaften.html" %}
                 </div>
             </div>
 
             <div class="navbar-item has-dropdown is-hoverable">
                 <a href="#" class="navbar-item">Updates</a>
-                <div class="navbar-dropdown">
+                <div class="navbar-dropdown is-boxed">
                     {% include "menu/updates.html" %}
                 </div>
             </div>