I want to change the size of thumbnail which is active 'image' in flexslider
Use the class .flex-active-slide
to style the active thumbnail.
Apply css transform also - transform: scale(1.1)
.
http://flexslider.woothemes.com/thumbnail-slider.html
#carousel .flex-active-slide img {
opacity: 1;
cursor: default;
transform: scale(1.1);
}