bbpress topic/reply on small screen-help

Hi sir, one of my site displays the profile and the content nicely on small screen, but the other site displays otherwise.

please view this one [ https://www.tajforum.com/picture-a/ ], bbpress displays the content under the user profile(horizontally). this is good for small screens.

please view this one too [ https://www.tajforum.com/picture-b/ ], bbpress displays the content side way of the user profile(vertically) and the avatar disappears on smaller screen. this is bad on small screens

thank so you much. forgive my poor explanations. kindly help me solve it please.