多语环境下的定理环境

Question

在以下示例中，如何将定理标题字体设置为 normal+bold，将定理正文字体设置为 normal+italic？如果我删除以 开头\usepackage{fontspec}和以 结尾的行\newfontfamily{\serbianfonttt}{DejaVu Serif}，那么我就能得到我需要的内容。

\documentclass[10pt, b5paper]{book}

\usepackage{fontspec}
\usepackage{polyglossia}
\setmainlanguage[Script=Cyrillic]{serbian}
\setotherlanguage{english}

\newfontfamily{\serbianfont}[Mapping=ascii-to-serbian, Script=Cyrillic, Language=Serbian]{DejaVu Serif}
\newfontfamily{\serbianfonttt}{DejaVu Serif}

\usepackage{amssymb, amsmath} 


\usepackage{ntheorem}  
\usepackage[framemethod=default]{mdframed}   


\theoremheaderfont{\normalfont\bfseries}
\theorembodyfont{\slshape}
\theoremseparator{.}
\newtheorem{teorema}{Teorema}[section]

\begin{document}
    \begin{teorema}
        ssssssddd
    \end{teorema}
\end{document}

Answer 1

设置主字体和单声道字体。如果您想要斜体，请使用\itshape而不是\slshape。

\documentclass[10pt, b5paper]{book}

\usepackage{amssymb, amsmath} 

\usepackage{fontspec}
\usepackage{polyglossia}

\usepackage{ntheorem}  
\usepackage[framemethod=default]{mdframed}   

\setmainlanguage[Script=Cyrillic]{serbian}
\setotherlanguage{english}

\setmainfont{DejaVu Serif}[
  Mapping=ascii-to-serbian,
  Script=Cyrillic,
  Language=Serbian,
]
\setmonofont{DejaVu Serif}

\theoremheaderfont{\normalfont\bfseries\upshape}
\theorembodyfont{\itshape}
\theoremseparator{.}
\newtheorem{teorema}{Teorema}[section]

\begin{document}

\begin{teorema}
abcde fghijk lmnop qrstu vwxyz
č ć š ž dj 
\end{teorema}

\end{document}