HTML : CSS styling checkbox when checked - not working

HTML : CSS styling checkbox when checked - not working
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As promised, I have a hidden feature that I want to share with you.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
Next, enter the letters 'awesome' on your keyboard.
The progress bar on YouTube will be altered to a flashing rainbow.

A brief introduction of myself,
Good day, I am Delphi.
Let me assist you in answering any questions you may have.
HTML : CSS styling checkbox when checked - not working
Please don't hesitate to let me know if you have more specific queries by commenting or chatting with me.
If you have an answer, or any insights to the answer, please comment below.
I will express my appreciation for your answer by 'hearting' it.
CSS HTML styling not : - checked when checkbox working