GUI - Scale GUIs According to Resolution

 void OnGUI()
 {
     GUI.DrawTexture(ResizeGUI(Rect(100, 100, 100, 100)), GuiTexture);
 }
 
 Rect ResizeGUI(Rect _rect)
 {
     float FilScreenWidth = _rect.width / 800;
     float rectWidth = FilScreenWidth * Screen.width;
     float FilScreenHeight = _rect.height / 600;
     float rectHeight = FilScreenHeight * Screen.height;
     float rectX = (_rect.x / 800) * Screen.width;
     float rectY = (_rect.y / 600) * Screen.height;
     
     return new Rect(rectX,rectY,rectWidth,rectHeight);
 }