TEXT IN CSS NOT FOUND BY WPML

I’m using the below CSS code to replace the cart widget amounts by a phrase.

/* REPLACE CART WIDGET AMOUNTS BY A PHRASE */
.wd-header-cart.wd-design-3 .wd-cart-subtotal:before {
	content: "SOUMETTRE MON DEVIS";
}

However, this string cannot be found by WPML. I found this forum but I’m not sure how I can apply this to my css code :
https://wpml.org/forums/topic/string-translation-for-text-inside-of-css/

Thanks