I had no problem.

Make sure you are not blocking content.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

One issue that seems more common lately is Firefox's Tracking Protection feature. When it is blocking content in a page, a shield icon will appear at the left end of the address bar next to the padlock icon. This article has more info on managing this feature: Tracking Protection {web link}

I assume that the website only supports modern cipher suites that your old Firefox 47 doesn't support. The website redirects to https://web2.0calc.com

I tested it with Firefox 45 and that also gives a blank page. This test gives a clue about what is wrong:

• Server negotiated HTTP/2 with blacklisted suite
• https://www.ssllabs.com/ssltest/analyze.html?d=web2.0calc.com&latest

And indeed, disabling http2 makes the website load, so you can give it a try:

• network.http.spdy.enabled.http2 = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• http://kb.mozillazine.org/about:config

I think that best is not to leave this pref false and you should reset the pref after you are done with the website.

Any specific reason you use this old Firefox version?

The System Details list shows you run an older Firefox 47 version that is no longer supported with security updates.

Please update to the current Firefox 66.0.3 release.

• Help -> About Firefox
• https://support.mozilla.org/en-US/kb/update-firefox-latest-version