raycast draw diagonal line problem?

i am trying to create 4 rays from all the object corner’s the problem the 4 ray’s combined in point under the plane how i can stop this and make them stay straight not diagonal

public class cubediminsion : MonoBehaviour
{

    Collider mcollider;
    float sizeX, sizeY, sizeZ;
    Vector3 collider_size;
        // Start is called before the first frame update
    void Start()
    {
        mcollider = GetComponent<Collider>();
        collider_size = mcollider.bounds.size;
        sizeX = mcollider.bounds.size.x;
        sizeY = mcollider.bounds.size.y;
        sizeZ = mcollider.bounds.size.z;
        Debug.Log("Collider Size : " + collider_size);
    }
    void raycastdraw()
    {
        Vector3 corner1 = transform.position + new Vector3(sizeX / 2, -sizeY / 2 + 0.1f, sizeZ / 2);
        Vector3 corner2 = transform.position + new Vector3(-sizeX / 2, -sizeY / 2 + 0.1f, sizeZ / 2);
        Vector3 corner3 = transform.position + new Vector3(sizeX / 2, -sizeY / 2 + 0.1f, -sizeZ / 2);
        Vector3 corner4 = transform.position + new Vector3(-sizeX / 2, -sizeY / 2 + 0.1f, -sizeZ / 2);
        Debug.DrawLine(corner1, Vector3.down, Color.blue);
        Debug.DrawLine(corner2, Vector3.down, Color.blue);
        Debug.DrawLine(corner3, Vector3.down, Color.blue);
        Debug.DrawLine(corner4, Vector3.down, Color.blue);
    }

    // Update is called once per frame
    void Update()
    {
        raycastdraw();
    }

i changed the debug.Drawline with debug.Drawray and problem solved sorry for newbies question