[OC 4.0.0.0_b] https cannot show pics & messes up website

Problem: When I access my site over https. it messes up display. With http, it works fine.

Root cause: The reason is as shown in the chrome dev tools
Mixed Content: The page at 'https://www.mysite.com/home' was loaded over HTTPS, but requested an insecure script 'http://my-srerver-name.com/vaayu/catalo ... 3.1.min.js'. This request has been blocked; the content must be served over HTTPS.

Questions:
Does anyone know how to fix for 4.0.0.0_b?
How to force links such as above with .js from opencart to use HTTPS? Are there any settings?

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Additional Details
Setup:
ubuntu and xampp.
Git SHA - c67de320f639229b114e0d537acb5351c3709935
I setup rule in /opt/lampp/etc/extra httpd-xampp.conf to redirect. Its working fine, if I type http://mysite.com -> It automatically changes to https://mysite.com
What I tried so far: Please suggest any additions/corrections
I checked the admin->system->settings, but dont find anything to enable.
My understanding from code is that, in 4.0, config.php does not need to define HTTPS_SERVER, HTTPS_CATALOG etc.

OpenCart 4.x is "alpha" state only.
So, no support here, use Github for that.