I came up with this custom userstyle for CCS pages other than FTS ones, sharing it in case someone is interested:
PHP Code:
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document url-prefix(http://127.0.0.1:8080/#library_id), url-prefix(http://127.0.0.1:8080/#book_id)
{
.book-list-custom-list, .book-details-panel{background-color:#e8e5ed !important;}
body{background-color:#5A57A5 !important;max-width:1000px!important;margin-left:200px!important;}
.book-search-panel, .generic-items-list, #panel-16, .edit-metadata-panel, .convert-book-panel{background-color:#e8e5ed!important;}
.book-list-container [data-component="top_message"]{color:white!important;}
/*.book-list-container {color:blue!important;}*/
/*.blue-link{color:#6cb4ee!important;font-weight:bold!important;}*/
.blue-link{font-weight:bold!important;}
#panel-14{color:#f8f8f8!important;}
}