Hover/rollover effect not working over breaks

Hi,

I have added a rollover effect for links on my blog which do not work if there is a br break between the words.
I’ve managed to do it once here (you can see it working on the third image from the bottom http://thefashannmonster.com/2015/02/osaka-travel-photologue-2/ where the words “Kani & Doraku both highlight on mouser even though they are not on the same line) but it hasn’t worked since then I can’t work out what is different from that one.

Could have an answer as to why it doesn’t work anymore?

Thank you!