There still is a good pool of casual gamers on the web. Traditional ways of deploying games for this platform required an extra plugin to be installed, but now, thanks to GWT and Libgdx, you can export your games directly to Javascript/HTML code.
GWT supports any of these browsers: Firefox, Internet Explorer (versions 8, 9, 10, and 11), Safari (versions 5 and 6), Chromium, Chrome, and Opera (latest version).
In order to go further in this recipe, it is necessary to install the Google plugin on your Eclipse. All you have to do is go to Help | Eclipse Marketplace. Then, search for Google Plugin and install the proper one according to your Eclipse version.
Finally, restart Eclipse and you will be ready to deploy to the browsers.
As can be expected, the samples-gwt project can be used to try the deployment process.