I remember that this is some inconvenience with some settings… was it focused window ?
I do not have this but i have no window focus indicator…
# (window-color) class border bground text indicator child_border
client.focused #7F7FFF $darkbluetrans $white #2E9EF4 #285577
client.focused_inactive #333333 #5F676A $white #484E50 #5F676A
client.unfocused #333333 #222222 #888888 #292D2E #222222
client.urgent $purple $urgentred $white $purple $lightdblue
# Smart borders (draw borders around container only if it is not the only container on this workspace)
set $smart_borders off
# default window borders
default_border none
default_floating_border 1pixel