Update md.css

Author: marshallino16

Snip/Resources/md.css

@@ -1,3 +1,17 @@
+.markdown-body {
+  box-sizing: border-box;
+  min-width: 200px;
+  max-width: 980px;
+  margin: 0 auto;
+  padding: 45px;
+}
+
+@media (max-width: 767px) {
+  .markdown-body {
+    padding: 15px;
+  }
+}
+
 .markdown-body .octicon {
   display: inline-block;
   fill: currentColor;