Github.io 404 problem

I made a homepage using html in https://github.com/yu-kim/ykkim-cookathome.github.io

After going through many processes, I created ykkim-cookathome.github.io.
But this link shows 404- site not found. Continue to do it again, make it new, but still show 404, site not found. I want to make my own site. Help me, please.

Try to rename index.HTML to index.html

Thank you for your answer. I changed to index.html, but I still have 404 problems. Do you know any other way? Please let me know.

oh wait, the name of your repo needs to be the same as your username profile (yu-kim), so your website will be hosted on https://yu-kim.github.io
sorry for the late reply.