"stylus" & "nib" use auto compiler for Express

app.js

var express = require('express');
var path = require('path');
var stylus = require("stylus"), nib = require("nib");

var app = express();

// app.use ...
app.use(stylus.middleware({
	src: path.join(__dirname, 'public'),
	compile: function (str, path){ return stylus(str).set("filename", path).set("compress", true).use(nib()); }
}));

app.use(express.static(path.join(__dirname, 'public')));

main.styl

@import 'nib'

body
  padding: 50px
  font: 14px "Lucida Grande", Helvetica, Arial, sans-serif
a
  color: #00B7FF
  
button
  border-radius 5px