Show border for button with mouse over

Below I have code that changes the color of the button with the onmouseover. How do I also include the border width with this?

Thanks!

Code:

---

        btnHome.Attributes.Add("onmouseover", "this.style.backgroundColor='#C6C6C6'")
        btnhome.Attributes.Add("onmouseout", "this.style.backgroundColor='#EFEFEF'")

---

try this

btnHome.Attributes["onmouseover"] = "this.style.backgroundColor='#C6C6C6';";
btnHome.Attributes["onmouseout"] = "this.style.backgroundColor='#EFEFEF';";