add noprint class to hide elements when printing

assets/styles/content.sass

@@ -10,6 +10,8 @@ a
   a.print:after
     content: " (" attr(href) ") "
     font-size: 50%
+  .noprint
+    display: none
 
 .synopsis
   .desc > p

includes/sections/copyright.pug

@@ -8,4 +8,5 @@ section.copyright
     |  Created with #[+ext_a('https://pugjs.org', 'pug')]
     |  and #[+ext_a('https://sass-lang.com', 'sass')].
     |  Built with #[+ext_a('https://parceljs.org', 'parcel')].
-    |  Pronunciation generated by #[+ext_a('https://ipa-reader.xyz', 'ipa-reader')].
+    |
+    span.noprint Pronunciation generated by #[+ext_a('https://ipa-reader.xyz', 'ipa-reader')].