Japanese by Example
Learning through examples in manga

You say that, but it's not important with だって

Manga panel from 三ツ星カラーズ showing example of You say that, but it's not important with だって.
三ツ星カラーズ » Volume 1 » Page 5

Yui hurries to her clubhouse to tell her friends, Kotoha and Sacchan, about a big case: there’s a cat that looks like a panda. However, Sacchan doesn’t engage in the topic and Kotoha continues playing her video game.

結衣(ゆい):
「もおマジメに()いてよ 琴葉(ことは)もっ」
“Geez, listen seriously. You too, Kotoha.”
さっちゃん:
だって全然(ぜんぜん)大変(たいへ)じゃないじゃん」
You say that, but it's not a big deal at all, right?”