Change top nav bar flat style to Bootstrap2 curved style

static/css/custom-variables.less

@@ -2,3 +2,8 @@
 @page-footer-color: #f5f5f5;
 @page-footer-height: 50px;
 @page-footer-height-subset: 16;
+
+@navbar-top-background-color: #FAFAFA;
+@navbar-top-background-image: linear-gradient(to bottom, #FFF, #F2F2F2);
+@navbar-top-border: 1px solid #D4D4D4;
+@navbar-top-box-shadow: 0px 1px 10px rgba(0, 0, 0, 0.1);

static/css/elegant.less

@@ -47,6 +47,15 @@ h1, h2, h3, h4, h5, h6 {
     }
 }
 
+.navbar-default {
+    &:extend(.navbar-default);
+    background-color: @navbar-top-background-color;
+    background-image: @navbar-top-background-image;
+    background-repeat: repeat-x;
+    border: @navbar-top-border;
+    box-shadow: @navbar-top-box-shadow;
+}
+
 .list-of-tags {
     font-family: @font-family-sans-serif;
     ul& {