how to take off the border of clicked button?

Hi, 
i'm using Valo theme and a borderless button. When I click it, there is a border with color blue and when I click somewhare else, the border disappears. now I want to take it off because I add other things to show the focus effect, like, a border-bottom line and hover.

I give the button my style name and I'm not sure only configuring my style will override the Valo style.

I have tried :focus, :active but with no luck.