Length unit relative to media width

Hi, I am new to this list. I don't know if any proposal similar to this has been discussed before. I have a proposal on a new length unit for use in CSS.

The unit should be relative to the screen (or paper) width.
The unit should be referenced to the preferred screen resolution.

I suggest those units:
   sw8      = (screen.width  /    800 ) px;
   sw12    = (screen.width  /  1200 ) px;
   sw16    = (screen.width  /  1600 ) px;
   sw24    = (screen.width  /  2400 ) px;

example:
H2 {   font-size: 36 sw12;  }

This should give font size 36 pixes in screen  resolution 1200x800. 
When displayed on a 800x600 screen resolution, the same font will be rescaled to 24 px. 
On a 1024 x 768 screen resolution, this font-size would be 31px  (rounded upward)

Gaute Sandvik