Add italics on tmux bell and activity windows

.tmux.conf

@@ -50,3 +50,5 @@ set-option -g status-right "#[fg=grey] %Y-%m-%d %H:%M "
 # Window list style
 set-window-option -g window-status-format "#[fg=grey]#I: #W"
 set-window-option -g window-status-current-format "#[fg=blue]#I: #W"
+set-window-option -g window-status-activity-style "bg=black, fg=grey, italics"
+set-window-option -g window-status-bell-style "bg=black, fg=grey, italics"