Text is too small while displaying in device

I customized for About screen. I wrote code for displaying text in screen. But when i run the app in device the texts are too small. See the attached image

 using UnityEngine;
 
 using System.Collections;
 
  
 
 public class Aboutscreen : MonoBehaviour {
 
  
 
  
 
  
 
  
 
 // public GUIStyle emptyButtonStyle;
 
  
 
 // Use this for initialization
 
 void Start () {
 
  
 
 }
 
  
 
 // Update is called once per frame
 
 void Update () {
 
  
 
 }
 
  
 
  
 
 void OnGUI()
 
     {
 
 GUI.Label(new Rect(10f, 160f, Screen.width, 250f), "1.Print the alphabet image targets located at");
 
  
 
 GUI.Label(new Rect(10f, 300f, 400f, 300f), "2.Point any of the animal images");
 
  
 
 GUI.Label(new Rect(10f, 460f, 400f, 400f), "3.Finally your kids able to see the 3D animal render on the screen with soundss");
 
  
 
 if(GUI.Button(new Rect(80,680,280,200), "start")) {
 
          Application.LoadLevel("25Nov1"); 
 
        }
 
  
 
        GUI.backgroundColor = Color.clear;
 
  
 
        if(GUI.Button(new Rect(260,160,120,250), "www.url.net")) {
 
          Application.OpenURL("http://www.url.net");
 
        }
 
 }
 
  
 
 }