How to make a panel centered with minimum and maximum width in Visual WebGUI?

I would like to make a panel with this behaviour in Visual WebGUI.

if window's width is smaller than minimal width of the panel, scrollbar appears. if window's width is bigger than minimal width of the panel, the panel fill the width of the window. if window's width is bigger than maximal width of the panel, panel remains at maximal width and sides of the window are empty.

Panel needs to be always in the center of the window.

How can I achieve that ? Thank you