Hello,
Please use this CSS:
#flatcal_minical .flatcal_main_t .flatcal_navbar tr td.link_prev,
#flatcal_minical .flatcal_main_t .flatcal_navbar tr td.link_next {
width: 15px;
display: block;
}
#flatcal_minical .flatcal_main_t .flatcal_navbar tr td.link_prev img,
#flatcal_minical .flatcal_main_t .flatcal_navbar tr td.link_next img {
height: 15px
}
Added to your JEvents Custom CSS section in the JEvents Control Panel. If it's still not showing after being added, please update your post with super user login details to take a look for you.
Many thanks
Tony