Latex 使一些字符变大

Question

尝试了 Python 代码颜色编码包，当我这样做时，整个文档中的字体突然开始变得奇怪。s、a、o 和其他一些字母的排版比其他字母大，整个文本看起来很奇怪。有人有什么想法吗？

\documentclass{article}
\usepackage[swedish]{babel}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{graphicx}

\usepackage[procnames]{listings}
\usepackage{color}

\begin{document}
\definecolor{keywords}{RGB}{255,0,90}
\definecolor{comments}{RGB}{0,0,113}
\definecolor{red}{RGB}{160,0,0}
\definecolor{green}{RGB}{0,150,0}

\lstset{language=Python, 
        basicstyle=\ttfamily\small, 
        keywordstyle=\color{keywords},
        commentstyle=\color{comments},
        stringstyle=\color{red},
        showstringspaces=false,
        identifierstyle=\color{green},
        procnamekeys={def,class}}

\title{Python}
\author{Some guy}

\maketitle

\newpage

\section{Objektorientering}
Såhär skapar man en klass i Py: 

\begin{lstlisting}
class Employee:
    empCount = 0        # kommer shareas av alla instanser

def __init__(self, name, salary):
    self.name = name
    self.salary = salary
    Employee.empcount += 1

def displayEmployee(self):
    print "Name : " self.name, "Salary: ", self.salary
\end{lstlisting}
\lstinline|__init__| är klasskonstruktorn som anropas varje gång man skapar en ny instans.
\end{document}