Description

The margins between elements rendered in this style and any other GUI elements.

This only has effect when using automatic layout (Additional resources: GUILayout).

using UnityEngine;

public class Example : MonoBehaviour
{
    // Prints the left, right, top and down values of the GUIStyle margin

    RectOffset rctOff;

    void OnGUI()
    {
        rctOff = GUI.skin.button.margin;
        Debug.Log("Left: " + rctOff.left + " Right: " + rctOff.right);
        Debug.Log("Top: " + rctOff.top + " Bottom: " + rctOff.bottom);
    }
}