Box "Out of stock" colors

[Monaloa]

Hello everyone,

I would like to change the color of the box "OUT OF STOCK", top right on the product picture.

Here it is Beige, like the other box "Dernières pièces", but I would like to change the color in black or another color.

I can't find the option in the theme, do you know if I can have add a code?

Thank you,

Best,

Pauline