Diverse small fixes

- Alter the CSS for tables to work with different ways of wring them.
  That makes these two selectors equivalent:

      table > tr:first-child
      table > thead
      table > :not(thead + tbody) > tr:first-child

  That also makes these two selectors equivalent:

      table > tr:nth-child(even)
      table > thead + tbody > tr:nth-child(odd)
      table > :not(thead + tbody) > tr:nth-child(even)

Reviewed-by: Tomas Mraz <[email protected]>
Reviewed-by: Paul Dale <[email protected]>
(Merged from #350)

Author: levitte

inc/screen.css

@@ -1569,8 +1569,12 @@ body > footer p:last-child {
 /* OPENSSL WEBSITE ADDITIONS */
 
 /* newsflash table */
-tr:first-child { font-weight: bold; border-bottom: 1px solid black; }
-tr:nth-child(even) { background-color: #D9f0ff; }
+table > tr:first-child, table > thead, table > :not(thead + tbody) > tr:first-child {
+    font-weight: bold; border-bottom: 1px solid black;
+}
+table > tr:nth-child(even), table > thead + tbody > tr:nth-child(odd), table > :not(thead + tbody) > tr:nth-child(even) {
+    background-color: #D9f0ff;
+}
 td.d { float: left; width: 20%; }
 td.t { float: right; width: 80%; }