PEP 8: Add green and red sidbar for good and bad examples (#3567)

pep_sphinx_extensions/pep_theme/static/style.css

@@ -148,6 +148,16 @@ pre {
     white-space: pre;
 }
 
+.good pre {
+  border-left: 3px solid rgba(74, 182, 93, 1);
+}
+.bad pre {
+  border-left: 3px solid rgb(244, 76, 78);
+}
+.maybe pre {
+  border-left: 3px solid rgb(244, 227, 76);
+}
+
 /* Contents rules */
 details > summary {
     cursor: pointer;
@@ -434,4 +444,4 @@ dl.footnote > dd {
   background: transparent;
   color: inherit;
   margin-top: 0;
-}
+}