css: Use "normal" font for captions

Emojis would be italicized on some browsers, which looked awful.

src/styles/styles.css

@@ -153,7 +153,7 @@ figure figcaption {
 }
 
 figure figcaption p {
-  font: italic smaller sans-serif;
+  font: normal smaller sans-serif;
   text-wrap: balance;
 }