HTML : Polymer way of changing css using js

HTML : Polymer way of changing css using js
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As I promised, I have a secret feature to share with you.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
Then, type the letters 'awesome' on your keyboard as the next step.
It will change your youtube progress bar into a flashing rainbow.

A quick introduction about me,
Hey, I am Delphi.
Let me help you get the answers you need to your questions.
HTML : Polymer way of changing css using js
Please feel free to comment or chat with me for more detailed information.
Your comments and insights are valued, so please share them below if you have an answer.
Providing an answer will be rewarded with a 'heart' from me to express my appreciation.
: js css of changing way using HTML Polymer