small improvements for box panels styling

src/sass/_variables.scss

@@ -441,7 +441,7 @@ $progress-bar-info-bg:          lighten($brand-info, 20%) !default;
 
 $panel-body-padding:            15px !default;
 $panel-color:                   #555 !default;
-$panel-bg:                      #f5f5f5 !default;
+$panel-bg:                      #f9f9f9 !default;
 $panel-border:                  #ccc !default;
 $panel-border-radius:           $border-radius-base !default;
 $panel-shadow:                  0 1px 2px rgba(#000, .1),

src/sass/components/_elements.scss

@@ -176,6 +176,11 @@ a.collapsible.collapsed,
         background: transparent;
         box-shadow: none;
     }
+
+    &:last-child,
+    >:last-child {
+        margin-bottom: 0;
+    }
 }
 
 

src/sass/components/_flash.scss

@@ -27,9 +27,7 @@
         background-position: $padding-large-horizontal 50%;
     }
 
-    p:last-child,
-    ol:last-child,
-    ul:last-child {
+    >:last-child {
         margin-bottom: 0;
     }
 }