dev #64073 : use button colors defined in colors.css

application/modules/admin/views/scripts/index/index.phtml

-<?php $skin = Class_Admin_Skin::current(); ?>
+<?php
+$skin = Class_Admin_Skin::current();
+?>
 <?php if ('stable' == BOKEH_VERSION) { ?>
 <h2 style="display:inline;border:none">
   <?php
+  Class_ScriptLoader::getInstance()
+  ->addInlineStyle('
+#learn_more_7_10 {
+  background-color:var(--bokeh-event);
+  padding:10px;
+  text-transform:uppercase;
+}
+#learn_more_7_10:hover {
+  background-color:var(--bokeh-event-highlight);
+}
+');
   echo $skin->renderMenuIconOn('tag', $this,
                                ['style' => 'vertical-align:middle'])
     . ' '
     . $this->_('Nouvelle version');
 
   $button = (new Class_Entity())->setText($this->_('Découvrir les nouveautés de la version 7.10'))
-                                ->setAttribs(['onclick' => 'window.open(\'http://wiki.bokeh-library-portal.org/index.php?title=7.10.0\'); return false',
-                                              'style' => 'background-color:#3377FF;padding:10px;text-transform:uppercase;']);
+                                ->setAttribs(['id' => 'learn_more_7_10',
+                                              'onclick' => 'window.open(\'http://wiki.bokeh-library-portal.org/index.php?title=7.10.0\'); return false']);
   echo $this->Button($button);
   ?>
 </h2>