light as in not heavy (low mass)?
You're my Light~
Am I the only one that hears 타벼운 instead of 가벼운?
I have noticed it in other sentences here too. Her 가 sounds 타 or 다 to me.
You should not ever trust in duolingo's pronunciation. It is better to study the sounds of Hangul with native, real people.
Where will we find natives.
There are some great korean study podcasts on youtube or you could purchase pimslur korean audio lessons on audible. Plus many more on other websites.