CSS : javascript add class to an element in a specific div

CSS : javascript add class to an element in a specific div
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 this video is playing.
Next, enter the letters 'awesome' on your keyboard.
You will see a flashing rainbow instead of a regular progress bar on YouTube.

A quick introduction about me,
Hello, I am Delphi.
I am at your disposal to help you with any questions you have.
CSS : javascript add class to an element in a specific div
I am available to answer your more detailed queries via comments or chat.
Your input is valuable, so please comment below if you have an answer or any insights to the answer.
A 'heart' from me will be given to show my gratitude for your contribution.
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