add code CSS

src/css/_code.css

+pre, .pre  {
+  overflow-x: auto;
+  overflow-y: hidden;
+  overflow:   scroll;
+}
+
+
+pre  code {
+  display: block;
+  padding: 1.5em 1.5em;
+  white-space: normal;
+  font-size: .875rem;
+  line-height: 2;
+
+}
+
+pre {
+  background-color: #222;
+  color: #ddd;
+  white-space: pre;
+
+  hyphens: none;
+  position: relative;
+}

src/css/main.css

 @import '_tachyons';
+@import '_code';
 @import '_hugo-internal-templates';
 @import '_social-icons';
 @import '_styles';