fixes #17017 (update padding:11px line 142 of rustbook.css)

Author: marti1125

src/rustbook/static/rustbook.css

@@ -139,7 +139,7 @@ h1, h2, h3, h4, h5, h6 {
 }
 
 pre {
-    padding: 16px;
+    padding: 11px;
     overflow: auto;
     font-size: 85%;
     line-height: 1.45;