"github.io" links are case-sensitive (Example: "Test.html" is not the same as "test.html")
https://coder4589.github.io or https://coder4589.github.io/index or https://coder4589.github.io/index.html
https://coder4589.github.io/test or https://coder4589.github.io/test.html
https://coder4589.github.io/elevatezoomplus-screenmode or https://coder4589.github.io/elevatezoomplus-screenmode.html
https://coder4589.github.io/inside-folder-test/ or https://coder4589.github.io/inside-folder-test/index.html