Add <code/> style.

src/index.css

@@ -38,3 +38,9 @@ main {
   }
 }
 
+code {
+  font-family: Courier, monospace;
+  background-color: rgba(27, 31, 35, 0.05);
+  border-radius: 3px;
+  font-size: 85%;
+  padding: 0.2em; }