我希望在宽页面内获得窄段落，以便章节标题、图形、表格都可能很宽，而段落都可能很窄。
\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\setlength{\parindent}{0pt} % so we can see better what is happening
\newenvironment{narrowpar}% I’d like every paragraph to follow these rules.
{\begin{list}{}{%
\setlength{\listparindent}{\parindent}%
\setlength{\itemindent}{\parindent}%
\setlength{\leftmargin}{2cm}%
\setlength{\rightmargin}{2cm}%
}\item }%
{\end{list}}
\begin{document}
\section{A section title that ranges across the page}
This is a paragraph (Loret Ipsum So On). And below, an equation that can make use of the whole page width:
\begin{equation}
p v = R T
\end{equation}
Here is another paragraph.
\begin{narrowpar}
This very text looks exactly the way I would like my paragraphs to look. But unfortunately it forces me to insert code manually before and after every paragraph in the source file.
\end{narrowpar}
\end{document}
换句话说，我试图控制所有段落的横向空间（用 HTML/CSS 来说就是“左右填充”），而不使用页边距。如能得到任何帮助，我将不胜感激...
答案1
您可以尝试使用\parshape命令重新定义段落形状：
\parshape 1 .15\hsize.65\hsize
参数 1：第一行，参数对：.15\hsize.65\hsize左边距和右边距。所有其他行将按第一行缩进。
它只对存在该命令的段落起作用。因此，您必须包含 的\parshape重新定义\par，即：
\def\par{\ifhmode\ownpar\fi\endgraf}
\def\ownpar{\parshape 1 .15\hsize.65\hsize}