Settings of this album
If the comment field of an image contains three dots ('...'), the comment after the three dots is displayed in a new window if the 'More info' link is clicked.
To see the extended comment, click on a thumbnail and next click the 'More info' link below the slide image. In this example album, the comment for the first image starts with: "Library ...The architect has tried to counteract the rigorous design of the former Town Hall, which is oblique with this playful building." The extended comment can't be displayed on the index page. In this album is the extended comment displayed in a new modal window, because check-mark "Clicking a 'More info' link opens a new window" on the Slide page options tab has been set.
The colors and the dimension of that new window are set on the 'Info window' tab, so they are equal to the colors and dimensions of the Info window you see here. You can use html tags in the descriptions.
More info in the PhotoSwipe user manual.