I checked your screenshot and link; yes css. The problem is slideshow div width which is calculated by slideshow plugin. when it load first time that div width is lower and then when you refresh it width rendered properly.
Try something like use featured image for first slide also, some width for class advps-slide-field-three instead width auto and also your used max-width property could create the problem for rendering div width properly.
So, if first two suggestion cant solve your problem then try using width rather then max-width for class advps-excerpt-three.