Adding text overlay to carousel banner on SquareSpace 7.0

Site URL: https://www.creativeinteriors-online.co.uk/

Hi guys, 

I hope you can help me.

How can I add text overlay on top of each of the three carousel images you see on the Homepage of https://www.creativeinteriors-online.co.uk/ website?

Your help would be greatly appreciated please.

Many thanks
Claudia

Add to Design > Custom CSS

section#homepage-carousel>div article:before {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    z-index: 99999;
    color: black !important;
    font-size: 100px !important;
}
section#homepage-carousel>div article:nth-child(4):before {
    content: "Slide 1" !important;
}
section#homepage-carousel>div article:nth-child(5):before {
    content: "Slide 2" !important;
}
section#homepage-carousel>div article:nth-child(6):before {
    content: "Slide 3" !important;
}

Thank you so much!!