HTML : Scaling iframes for responsive design CSS-only

HTML : Scaling iframes for responsive design CSS-only
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

So here is a secret hidden feature I promissed to tell you.
This is a YouTube's feature which works on Desktop.
First, Make sure this video is playing.
After that, type the word 'awesome' on your keyboard.
It will change your youtube progress bar into a flashing rainbow.

An introduction to myself in a few words,
Good day, I am Delphi.
Allow me to support you in answering your questions.
HTML : Scaling iframes for responsive design CSS-only
I am available to answer your more detailed queries via comments or chat.
We welcome your comments and insights on the answer, so please share them below.
A 'heart' from me will indicate my appreciation for your answer.
for : Scaling responsive HTML iframes design CSS-only