I am doing a Soduko Solver website which i am hosting on github for personal use however i get this error and it wont display the soduko solver which i am integrating/getting from another online source, locally the website displays as it should but on github it doesnt, i tried several methods including putting the

 <meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">

But it doesnt seem to work and i am stuck with the same error "Mixed content: load all resources via HTTPS to improve the security of your site" Its blocking the "embed.html" found at http://sudokusolver.net/embed.html