Can't find how to properly keep GUIs proportional to screen?

There’s screen.width / 2 and screen.height / 2 for centering a guitexture or a buibox, but how exactly can I keep both the size and position proportional to different aspect ratios? Even if I have like a GUI box for a background of a menu, and then some buttons, how can I ensure the buttons and their positions will be the same when the resolution changes? Can someone please either give me some help or point me to a question where this was answered? I couldn’t find any.

You have to calculate things yourself for this one.
Instead of having a button appear 10px from the left, you just say screen.width/20.
You’ll have to do this for everything though. Everything should be relative to the screen sizes.

Or, hardcode all your GUI measurements with a particular screen resolution in mind, and use GUI.matrix to rescale it to the actual screen resolution. e.g.:

var native_width : float = 1920;
var native_height : float = 1080;
function OnGUI ()
// Calculate scaling
var rx : float = Screen.width / native_width;
var ry : float = Screen.height / native_height;
GUI.matrix = Matrix4x4.TRS (Vector3(0, 0, 0), Quaternion.identity, Vector3 (rx, ry, 1));
// Now create GUI in the "native" resolution (in this example, 1920x1080)
GUI.Box(Rect(810, 490, 300, 100) , "This is a box in the middle of the screen.");