How to set which margin/padding to shrink first?

Hi there,

i am having a general question - maybe a dumb one.
If you look at the container in the attached link - i added vertical text and horizontal text (with white background) and positioned it.
When i reduce the size of my browser window with my current settings the text-box shrinks first (and the lines start to stack) while the space a) between vertical and white-boxed texed and b) between white-boxed text and right size of the screen stays the same.

Is there a way to shrink a) and b) before the text-box is shrinked (until the vertical+white-box collide (but not overlap)?
I played around with the container settings a lot - but couldnt figure out how to do so.