[basic.link], [expr.ref] Harmonize font for tuple representing direct base class relationship

Fixes NB US 1-405 (C++26 CD).

Author: eisenwave

source/basic.tex

@@ -3268,10 +3268,10 @@
 \item
 an entity, value, or object that is TU-local,
 \item
-a direct base class relationship (\tcode{D}, \tcode{B})\iref{class.derived.general}
-for which either \tcode{D} or \tcode{B} is TU-local, or
+a direct base class relationship $(D, B)$\iref{class.derived.general}
+for which either $D$ or $B$ is TU-local, or
 \item
-a data member description ($T$, $N$, $A$, $W$, $\mathit{NUA}$)\iref{class.mem.general}
+a data member description $(T, N, A, W, \mathit{NUA})$\iref{class.mem.general}
 for which $T$ is TU-local.
 \end{itemize}
 \end{itemize}

source/expressions.tex

@@ -4222,7 +4222,7 @@
 then let \tcode{T1} be the type of \tcode{E1}.
 \tcode{E2} shall designate either
 a member of \tcode{T1} or
-a direct base class relationship $(\tcode{T1}, \tcode{B})$.
+a direct base class relationship (\tcode{T1}, \tcode{B}).
 
 \pnum
 If \tcode{E2} designates a bit-field, \tcode{E1.E2} is a bit-field. The