Different background image for Taglines on Portfolio Detail only

Hi

I want to know if it’s possible to have a background image in the “tagline” for the portfolio items?

I tried to use this css code but it wouldn’t override the tagline:

.ish-part_tagline.ish-tagline-colored .ish-overlay {
background-image:url (https://www.mystic.com.co/fluotest/wp-content/uploads/2015/05/test-header-tagline.jpg)!important;
}

Thanks