Making a GUITexture Menu proportional to screen resolution

I want to make the size of my GUITexture buttons' dimensions about a sixth of the size of my screen's height. Right now, I also want my GUITextures to move relative to the main GUITexture menu stated below. Here's what I have so far:

 using UnityEngine;
 using System.Collections;
 
 public class InventoryScriptBox : MonoBehaviour
 {
     public GUITexture texture;
     public InventoryScriptMain mainInventory;
     float mainX;
     float mainY;
     public float offsetX;
     public float offsetY;
     public float width;
     public float height;
     
     int screenWidth = Screen.width;
     int screenHeight = Screen.height;
     
     float ratioX = Screen.width/5.0f;
     float ratioY = Screen.height/5.0f;
     
     public int indexX;
     public int indexY;
     
     // Use this for initialization
     void Start ()
     {
         GUI.depth = 3;
         mainX = mainInventory.guiTexture.pixelInset.x * ratioX;
         mainY = mainInventory.guiTexture.pixelInset.y * ratioY;
         texture.guiTexture.pixelInset = new Rect(mainX + offsetX, mainY + offsetY, ratioX, ratioY);
         Debug.Log (ratioX + ", " + ratioY);
     }
     
     // Update is called once per frame
     void Update ()
     {
         mainX = mainInventory.guiTexture.pixelInset.x;
         mainY = mainInventory.guiTexture.pixelInset.y;
         texture.guiTexture.pixelInset = new Rect(mainX + offsetX, mainY + offsetY, ratioX, ratioY);
     }
     
     void OnMouseDown()
     {
         //Debug.Log("Mouse Down Box " + indexY + ", " + indexX);
         Debug.Log (screenWidth + ", " + screenHeight);
     }
 }