If an Element’s width is not set in either a % or VH unit, then the Element must also have modified mobile styles. We recommend changing the unit to % or VH so it also influences your event's mobile and tablet views.
When you're looking at your element in the layout panel, select Width, height and simply change your width unit to % or VH. Depending on the value you set the width, it may get smaller or larger. Be sure to change it accordingly to make it consistent with the rest of your page’s content.