hide half of the line number on printing

static/css/markdown.css

@@ -254,6 +254,11 @@ table:not(.hljs-ln) tr th:last-child {
     page-break-inside: avoid;
   }
 
+  /* Skip some numbers lines in codeblocks */
+  tbody tr:nth-child(even) .hljs-ln-numbers {
+    visibility: hidden;
+  }
+
   @page {
     @bottom-right {
       content: counter(page) "/" counter(pages);