Unicode characters in CSS generated content

I ran across an issue today where I had set some generated content to an unusual character (an open quotation mark), but the compiled and minified CSS served by Drupal was showing me the wrong characters. It was likely caused by character encoding getting screwed up somewhere along the line. The solution was to specify the Unicode character I wanted in the format seen in the code block below, as demonstrated in the source link below and this Stack Overflow answer.

Code language: CSS

p:before {
  content: "\201C";