The width of the object is tied to the width of the window. How to set height equal to width?

Question

css

The width of the object is 10% of the width of the window.
How can I set the height of an object to be equal to the width so that the object remains square regardless of the screen aspect ratio of the device?

Answer 1

Sandbox example

div {
    width: 10%;
    height: 10vw;
}

Answer 2

Perhaps this is the answer www.mademyday.de/css-height-equals-width-with-pure...