add border to rendered markdown with cell toolbar

matches unrendered markdown and code cells

IPython/html/static/notebook/less/celltoolbar.less

@@ -31,12 +31,17 b''
 }
 
 .ctb_global_show .ctb_show + .input_area,
-.ctb_global_show .ctb_show + div.text_cell_input
-{
+.ctb_global_show .ctb_show + div.text_cell_input,
+.ctb_global_show .ctb_show ~ div.text_cell_render {
     border-top-right-radius: 0px;
     border-top-left-radius: 0px;
 }
 
+.ctb_global_show .ctb_show ~ div.text_cell_render {
+    // add border to rendered markdown cells
+    border: @border_width solid @light_border_color;
+}
+
 .celltoolbar {
     font-size: 87%;
     padding-top: 3px;

IPython/html/static/style/style.min.css

@@ -10157,10 +10157,14 b' p {'
   display: block;
 }
 .ctb_global_show .ctb_show + .input_area,
-.ctb_global_show .ctb_show + div.text_cell_input {
+.ctb_global_show .ctb_show + div.text_cell_input,
+.ctb_global_show .ctb_show ~ div.text_cell_render {
   border-top-right-radius: 0px;
   border-top-left-radius: 0px;
 }
+.ctb_global_show .ctb_show ~ div.text_cell_render {
+  border: 1px solid #cfcfcf;
+}
 .celltoolbar {
   font-size: 87%;
   padding-top: 3px;