Photoswipe fonts

I am pretty sure PhotoSwipe has not fonts of its own – it inherits from your theme. You should be able to change it using custom CSS (from your WP dashboard, under Appearance → Customize → Additional CSS). If you provide me with a link, I can tell you how.

I am using the wpastra theme.
At this moment on a local virtual machine. So I can not give you a link.

I can install it on a hosted environment tomorrow and send you a link then.

Regards,
Hans

I mean Astra theme.

Solved, added the css below :

/* color and textsize for gallery caption bottom*/
.title-display-slideup-stick a .photonic-title {
  font-size: 1em;
  color: whitesmoke ;
}

/* text color and size in photoswipe */
.pswp * {
  color: red;
	font-size: 18px;
}

/* color and textsize for gallery caption below */
a.photonic-lb.photonic-photoswipe.photoswipe {
    text-decoration: none;
	  color:black;
	  text-align: center;
	  font-size: 1.2em;
}