Editing border-top colours

Sup guys, i'm using the theme chocolate and since i've added some blocks they're a different colour to the rest. I want to change the purple colour to the red colour, I've searched everywhere in the .css files but still can't manage to find where or how to do it, I've also searched up the red colour code and rgb code in all .css files and still nothing.

---

please help, this is driving me fucking mental lmfao.