Avoid using important

IPython/html/static/notebook/less/cell.less

@@ -8,10 +8,18 b' div.cell {'
 
     &.selected {
         border-color: @border_color;
+        /* Don't border the cells when printing */
+        @media print {
+            border-color: transparent;
+        }
     }
 
     &.edit_mode {
         border-color: green;
+        /* Don't border the cells when printing */
+        @media print {
+            border-color: transparent;
+        }
     }
 
     width: 100%;
@@ -21,13 +29,6 b' div.cell {'
     outline: none;
 }
 
-/* Don't border the cells when printing */
-@media print {
-    div.cell {
-        border-color: transparent !important;
-    }
-}
-
 div.prompt {
     /* This needs to be wide enough for 3 digit prompt numbers: In[100]: */
     min-width: 15ex;

IPython/html/static/notebook/less/codecell.less

@@ -1,6 +1,6 b''
+div.code_cell {
 /* avoid page breaking on code cells when printing */
 @media print {
-    div.code_cell {
         page-break-inside: avoid;
     }
 }

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

@@ -90,11 +90,14 b' p {'
 
 .notebook_app #header {
     .box-shadow(@notebook-shadow);
+    @media print {
+        display: none;
+    }
 }
 
 /* Hide the header when printing */
 @media print {
-    #header, #header-spacer {
-        display: none !important;
+    #header-spacer {
+        display: none;
     }
 }