Preventing indentation in first line of code blocks

Previously, the first line of each block-level `<code>` element
was indented by 6 pixels. That problem was accidentally introduced
in 0a36e05. That commit added the
indent for inline `<code>` elements, but inadvertantly also added
it for block level `<code>` elements as well.

Author: jstrait

web/beats.css

@@ -180,6 +180,7 @@ pre.single-line {
 
 pre code {
   background: none;
+  padding: 0;
   line-height: 0.6666666667rem;
 }