Since the rendering is done using Hexo, you can configure it in the forked GitHub repository. The current theme in use is Fluid, and you can also modify the corresponding theme configuration.
For example, to change the title of the site, you can modify the title in _config.yml.
If you want to update the background image of the homepage, you can modify index.banner_img in _config.fluid.yml.
References:
- Hexo Documentation: https://hexo.io/
- Fluid theme documentation: https://hexo.fluid-dev.com/docs/en/guide/