Screen.width Not Working

Hey everyone,

I'm trying to make a slider bar along the bottom of my screen with a length equal to 1/2 the width of the screen. I have sliders on the left & right of my screen properly functioning as vertical sliders, however the horizontal slider appears in the center of my screen (telling me it is calculating screen.width properly), however, the slider itself is not the proper length (keeps appearing as approximately 1/10 screen.width) and I have no clue why!

Any help would be much appreciated. Here is my code:

 using UnityEngine;
 
 using System.Collections;
 
 public class GUI : MonoBehaviour {
     
     #region Variables
     //Slider Control Values
     public float sliderMin = 0.0f;
     public float sliderMax = 360.0f;
     public float xSliderValue;
 
     //Slider Layout Variables
     public int horzSliderLength = (Screen.width / 2);
     public int horzSliderWidth = 15;
 
     //General GUI Layout
     public int screenMargin = 10;
     public int sliderLabelWidth = 40;
     public int sliderLabelHeight = 25; 
     #endregion
 
 void OnGUI ()
     {
     #region Sliders
         //X-axis Slider (bottom middle of screen)
         xSliderValue = GUI.HorizontalSlider(new Rect((Screen.width / 2) - (horzSliderLength / 2), (Screen.height - ((horzSliderWidth / 2) + screenMargin + sliderLabelHeight)), horzSliderLength, horzSliderWidth), xSliderValue, sliderMin, sliderMax);  
     #endregion
     }
 }

THANK YOU!