In order to use bootstrap, there are 2 cases.
For electron apps that are connected to internet, we can just make use of CDN links for bootstrap and include that in our html files.
The problem comes when we have to take it to offline version where the app is not connected to the net. In that case,
<link rel="stylesheet" href="path_to_the_offline_bootstrap_css_file"> <script scr="path_to_the_offline_bootstrap_js_file"></script>
In this way you can start using twitter bootstrap in electron framework.