Better-delimited styling of code fragments in article text

Non-fenced code fragments (using backticks in Markdown) will now be
formatted with a background color, padding, and a border.  I was
avoiding this for some time, but most of my writing also didn't have a
whole lot of code in it.  That's changing with the article I'm writing
now, and it really is much more clear with this styling; it can
otherwise be more difficult than necessary to tell where a command
starts and ends, and the monospace font can sometimes be too sublte of
an indicator for shorter text, or text that uses characters that are
harder to distinguish.

style.css

@@ -512,6 +512,14 @@ article img {
   margin: 0 auto;
 }
 
+/* Non-fenced code (e.g. backticks) */
+article code:not(.sourceCode) {
+  background-color: #f8f8f8; /* matches pandoc */
+  border: 1px solid rgba(0, 0, 0, 0.15);
+  border-radius: 0.25em;
+  padding: 0.15ex 0.15em;
+}
+
 
 /* Two columns on larger displays */
 @media ( min-width: 90ch ) {