\newtheorem 标题和正文的字体大小与文档其余部分不同

Question

我正在使用没有指定字体大小的书籍文档类，所以它应该是默认的 10pt。

在 \begin{document} 之后，我有行 \fontsize{9}{10.8} 将所有字体更改为 9pt。

\documentclass{book}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
  %{\topsep}{\topsep}%
  {8pt}
  {8pt}
  {}{}%
  {\bfseries}{}%
  {\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

\fontsize{9}{10.8}

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}


\end{document}

标题“测试”和正文小于 \fontsize 中指定的 9pt。

这是多小的字体大小？我可以用 \fontsize 让整个文档以这种较小的字体大小输出吗？还是 \fontsize 导致这两种字体大小？

Answer 1

声明\fontsize{9}{10.8}直到发布后才生效\selectfont。这在定理中发生，但在上面的文本中没有发生。

\documentclass{book}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
  %{\topsep}{\topsep}%
  {8pt}
  {8pt}
  {}{}%
  {\bfseries}{}%
  {\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

\fontsize{9}{10.8}\selectfont

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}


\end{document}

另一方面，使用专门的类来实现这一点似乎更好。

\documentclass[9pt]{extbook}

\usepackage{bookman}
\usepackage{amsthm}

\newtheoremstyle{break}
  %{\topsep}{\topsep}%
  {8pt}
  {8pt}
  {}{}%
  {\bfseries}{}%
  {\newline}{}%
\theoremstyle{break}
\newtheorem{test}{Test}
\counterwithin*{test}{subsection}

\begin{document}

The quick brown fox jumps over the lazy dog. This font looks to be 9pt.

\begin{test}
This is the test.  This seems to come out smaller.
\end{test}


\end{document}