Template:Citation/styles.css

 /* {{pp|small=y}} */
 /*
  * This page is a convenient place for the "citation" styles that are
  * available in many of our citation templates. This page can be considered the
  * authoritative source for those styles. [[Template:Citation]], like all CS1/2
  * templates, is styled from [[Module:Citation/CS1/styles.css]], *not* here.
  */
 /* Break long urls, etc., rather than overflowing box */
 .citation{
 word-wrap:break-word;
 }

 /* Highlight linked elements (such as clicked references) in blue */
 .citation:target{
 /* ignore the linter - all browsers of interest implement this */
 background-color:rgba(0,127,255,0.133);
 }