Set code font family to respective variable

packages/codemirror/style/index.css

@@ -22,6 +22,7 @@
 .CodeMirror {
   line-height: var(--jp-code-line-height);
   font-size: var(--jp-code-font-size);
+  font-family: var(--jp-code-font-family);
   height: auto;
   /* Changed to auto to autogrow */
   background: none;