Make area adapt to screen size

Anybody know how to do this?

I made my own attempt but it doesn’t seem to to work:

GUILayout.BeginArea(new Rect((Screen.width/2) - Screen.width * (0.5f/5f), (Screen.height/2) - Screen.height * (0.5f/4.0f), Screen.height * (3f/5f), Screen.width * (0.75f/5f)), GUIContent.none, "box");

GUILayout works a bit weird, but this has been successful for me (I have no idea why though):

GUILayout.BeginArea(new Rect(Screen.width/3, Screen.height/2.7f, (Screen.width) - (Screen.width/1.5f), (Screen.height) - (Screen.height/1.5f)), GUIContent.none, "box");

This adapts perfectly to the screen. I don’t know why the other one doesn’t.