CSS scale height to match width - possibly with a formfactor

Question

I have implemented a GoogleMapsV3 map in a twitterBootstrap basic responsive design site.

But my question is quite simple: i have:

Answer 1

Try viewports

You can use the width data and calculate the height accordingly

This example is for an 150x200px image

width: calc(100vw / 2 - 30px);
height: calc((100vw/2 - 30px) * 1.34);