Support theming for the header logo

refs #10705

application/layouts/scripts/body.phtml

@@ -19,21 +19,16 @@ if ($this->layout()->autorefreshInterval) {
 ?>
 <div id="header">
   <div id="logo">
-  <?php if (Auth::getInstance()->isAuthenticated()): ?>
     <?= $this->qlink(
       '',
-      'dashboard',
+      Auth::getInstance()->isAuthenticated() ? 'dashboard' : '',
       null,
       array(
-        'icon'              => 'img/logo_icinga-inv.png',
         'data-base-target'  => '_main',
         'aria-hidden'       => 'true',
         'tabindex'          => -1
       )
     ); ?>
-  <?php else: ?>
-    <?= $this->icon('img/logo_icinga-inv.png'); ?>
-  <?php endif ?>
   </div>
 </div>
 <?php if (! $this->layout()->isIframe): ?>

public/css/icinga/header-elements.less

@@ -1,18 +1,18 @@
 /*! Icinga Web 2 | (c) 2013-2015 Icinga Development Team | GPLv2+ */
 
 #logo {
-  height: 4.0em;
-  width: 13em;
-  display: inline-block;
-}
-
-#logo a {
-  display: block;
-  outline: 0;
-}
-
-#logo img {
-  width: 100px;
+  height: 4em;
   margin-left: 1.5em;
-  margin-top: 0.8em;
+  margin-top: 0.2em;
+  margin-bottom: 0.2em;
+  width: 100px;
+}
+
+#logo > a {
+  background-image: url('../img/logo_icinga-inv.png');
+  background-position: center;
+  background-repeat: no-repeat;
+  background-size: contain;
+  display: block;
+  height: 100%;
 }