Zend certified PHP/Magento developer

Magento2 – reduce size of style-m.css?

I read up on the use of less files by Magento.
I checked the size of the two files inside the pub/static folder and I noticed that the style-m.css file is twice the size of style-l.css.

Why?
I simply activated the blank theme and yet the css file for mobile is double the size of style-l.css

How can I reduce the weight of style-m.css?
Can I disable, for example, from compiling “media-common”?

Thanks for any help