added missing bg-secondary classes

tracim/tracim/templates/page/getone.mak

 
 <div class="content-container ${'not-editable' if not result.page.is_editable else ''} ${'archived' if result.page.is_archived else ''} ${'deleted' if result.page.is_deleted else ''}">
 
-    <div class="t-page-header-row">
+    <div class="t-page-header-row bg-secondary">
         <div class="main">
             <h1 class="page-header t-page-color-border">
                 <i class="fa fa-fw fa-lg fa-file-text-o tracim-less-visible t-page-color"></i>

tracim/tracim/templates/widgets/row.mak

 <%def name="TITLE_ROW(label, icon, width_classes, color_classes, subtitle)">
-    <div class="" style="background-color: #F5F5F5; border-bottom: 1px solid #CCC;">
+    <div class="bg-secondary" style="border-bottom: 1px solid #CCC;">
         <div class="${width_classes} main">
             <h1 class="page-header ${color_classes}">
                 <i class="fa fa-fw fa-lg ${icon} ${color_classes}"></i>