Unable to load external css file with node/express - 404 error

Hello I have got to configure an express app in an architecture that look like this:

![my architecture][1]


Build
Core/pulse.core/assets/styles/global.css
app.js
Express_app
  views/home.jade
  controller/routes.js
node_modules

my app.js looks like this:

var express = require('express'),
    http = require('http'),
    fs = require('fs'),
    path = require('path');

var app = express();

html_templates = __dirname + '/Express_app';

app.set('views', html_templates + '/views');
app.set('view engine', 'jade');

app.use("/Core", express.static(__dirname + 'Core/Pulse.Core/Assets/Styles/'));


app.listen(3000, function () {
    console.log("express has started on port 3000");
});

require('./Express_app/controller/routes.js')(app);

in my home.jade file, i have:

link(rel="stylesheet", href=levelarbo+"../../Core/Pulse.Core/Assets/Styles/global.css")

My html is loading fine, however, i am getting a 404 for my css file, please help. I have been stuck on this for hours :(