I am not able to add CSS files in node JS

I am not able to add css and js file please give me a code by which i can use my css or other files This is my code:

const http = require('http');
const fs = require('fs');

const port = 3000;
fs.readFile('index.html',(err,html) => {
    if(err){
        throw err;
    }

    const server = http.createServer((req,res) => {
    res.statusCode = 200;
    res.setHeader('content-type', 'text/html');
    res.write(html);
    res.end();
    });
server.listen(port, hostname, () =>{
    console.log("server started on port: "+port)
    });
});


my file location is
test.js
index.html
public /css==>here my css files
       /js ==>here my other js files