Author did not enable high-DPI support in his/her application. As simply as that...
Either in Visual Studio : https://sciter.com/wp-content/uploads/2024/06/high-dpi-aware...
Or by including proper manifest: https://gitlab.com/sciter-engine/sciter-js-sdk/-/blob/main/d...
That actually is explained in "Hello C++" tutorial: https://sciter.com/hello-cpp-tutorial/