GUI Resolution Ajust

How do I do to Make the GUI fit to the screen resolution, so when the resolution resize the GUI fit the resolution.

Here the Script

function OnGUI () {
if(municaoSelect){

    (GUI.Button (Rect (guix,guiy,300,20), "Aperte E para pegar " + municao + " de municao."));
}

}

GUI.Button(new Rect(Screen.width * (1f/6.55f),Screen.height * (0.1f/6.3f),Screen.width * (4.8f/6.55f), Screen.height * (0.85f/6.3f)),“Click”); //c#

GUI.Button(Rect(Screen.width * (1f/6.55f),Screen.height * (0.1f/6.3f),Screen.width * (4.8f/6.55f), Screen.height * (0.85f/6.3f)),"Click"); //java script

this will adjust the GUI depending on screen reslotion