If I had chosen a simple text the above would work
selector{color:red}
but I have not added a plain text, but I see a title that emerged from the plugin 3d flipbook.
To take from the beginning:
I have install the 3dflipbook plugin
2)from this plugin i chose a pdf file from my library
3)I choose to display only the title of the file on my page, for example “BOOK1”
4)The plugin creates the Shortcode