css - Landscape layout change to portrait -

i have giant project made landscape desktop computers using google chrome browser.

but requirement has run in portrait computer (its not mobile/ipad/tablet device, all-in-one touch screen computers). looking smart way still not find any.

<div id='i_wasdesigned_for_landscape'> landscape: texts horizontally left right <button>left right: 1</button> <button>left right: 2</button> </div> 

now need fit this: i_wasdesigned_for_landscape portrait screen how can fit it?

use:

transform: rotate(-90deg); zoom: 0.95;