adding .css file to ejs

im working on node.js(express) with ejs and im not able to include a .css file to it.i tried the same thing seperately as a html-css duo and it worked fine...how can i include the same in my .ejs file. My app.js goes thus:

var express = require('express');
var app = express();

app.set('views', __dirname + '/views');


app.get('/', function(req, res){
  res.render('index.ejs', {
        title: 'My Site',
    nav: ['Home','About','Contact'] 
  });
});

app.get('/home', function(req, res){
  res.render('index.ejs', {
        title: 'My Site',
    nav: ['Home','About','Contact'] 
  });
});

app.get('/about', function(req, res){
  res.render('about.ejs', {
    title: 'About',
     nav: ['Home','About','Contact']
  });
});

app.get('/contact', function(req, res){
  res.render('contact.ejs', {
    title: 'Contact',
     nav: ['Home','About','Contact']
  });
});


app.listen(3000);

and the index.ejs file:

<html>
<head>
<link href="style.css" rel="stylesheet" type="text/css">

</head>
<body>
<div>
    <h1> <%= title %> </h1>
    <ul>
<% for (var i=0; i<nav.length;i++) {%>

<li><a href="/<%=nav[i]%>"> <%=nav[i]%> </a></li>
   &nbsp;  
<% } %>
   </ul>
</div>

<br>
<h3>Node.js</h3>
<p class='just'>Express is agnostic as to which templating language you use. Templating languages can be a hot topic of debate.Here Iam going to use Jade.</p>
<p class ='just'>Again Express is agnostic to what you use to generate your CSS-you can use vanilla CSS but for this example I'm using Stylus.
</p>
<footer>
Running on node with express and ejs
</footer>
</home>
</html>

style.css file:

<style type="text/css">
body { background-color: #D8D8D8;color: #444;}
h1 {font-weight: bold;text-align: center;}
header { padding: 50px 10px; color: #fff; font-size :15px; text-align:right;}
 p { margin-bottom :20px;  margin-left: 20px;}
 footer {text-decoration: overline; margin-top: 300px}
 div { width:100%; background:#99CC00;position:static; top:0;left:0;}
 .just
 {
    text-align: center; 

 }
a:link {color:#FF0000;}    /* unvisited link */
a:visited {color:#0B614B;} /* visited link */
a:hover {color:#B4045F;}   /* mouse over link */
a:active {color:#0000FF;}

  ul { list-style-type:none; margin:0; padding:0;text-align: right; }
li { display:inline; }
</style>

Solution

Your problem is not actually specific to ejs.

2 things to note here

style.css is an external css file. So you dont need style tags inside that file. It should only contain the css.
In your express app, you have to mention the public directory from which you are serving the static files. Like css/js/image

it can be done by

app.use(express.static(__dirname + '/public'));

assuming you put the css files in public folder from in your app root. now you have to refer to the css files in your tamplate files, like

<link href="/css/style.css" rel="stylesheet" type="text/css">

Here i assume you have put the css file in css folder inside your public folder.

So folder structure would be

.
./app.js
./public
    /css
        /style.css