Font weight of smaller font that runs over header slider images

Hello, I’d like to make the smaller font running over my full frame slider images bolder so it’s more readable over my images. I hope it’s just a matter of adding a bit of css via the Customer CSS tool? If so, what would it be?

btw, the staged site is at


Add this CSS code to: Customize > additional CSS:

.text-slider .subtitle {
    font-weight: bolder;