added correct content type for css

main.go

@@ -46,6 +46,9 @@ func static(w http.ResponseWriter, req *http.Request) {
 		http.Error(w, "file not found", http.StatusNotFound)
 		return
 	} else {
+		if req.URL.Path == "/math.css" {
+			w.Header().Set("Content-Type", "text/css")
+		}
 		_, err := w.Write(content)
 		if err != nil {
 			http.Error(w, "problem writing response", http.StatusInternalServerError)