title: Not able to secure website on Firefox even after installing SSL certificate
body: <p>I am using the below code to install SSL certificate on my website:</p>
  
  <pre><code>const express = require('express');
  const path = require('path');
  const app = express();
  const fs= require('fs');
  let privateKey = fs.readFileSync('certificate/x.key', 'utf8');
  let ca = fs.readFileSync('certificate/x.crt', 'utf8');
  let certificate = fs.readFileSync('certificate/x.crt', 'utf8');
  let credentials = { key: privateKey, cert: certificate, ca: ca };
  const http = require('http');
  const https = require('https');
  
  app.use(express.static(path.join(__dirname, 'build')));
  
  app.get('/*', function(req, res) {
    res.sendFile(path.join(__dirname, 'build', 'index.html'));
  });
  
  let httpsServer = https.createServer(credentials, app);
  
  httpsServer.listen(443);
  </code></pre>
  
  <p>This is a react app and I am serving it via Node.js.</p>
  
  <p>When I open the website on Chrome or Microsoft Edge, it shows the connection as secure, encrypted and valid but when I open it on firefox, it shows that the connection is not secure.
  <a href="https://i.stack.imgur.com/J6XmP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/J6XmP.png" alt="Valid in Chrome"></a>
  <a href="https://i.stack.imgur.com/Nftl6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Nftl6.png" alt="Not working in Firefox"></a></p>
  
  <p>What could be the problem?</p>