[Tex/LaTex] How to add a colored box around the theorems

Question

I am very new to LaTeX and would like to give my small booklet im writing on a little bit more style and structure. Every time I add an definition to my text I would like to let LaTeX automatically add a green box around it so the layout gets a little bit more structured. Here is an example of my code:

\documentclass[a4paper,10pt]{scrartcl}

\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}
\usepackage[a4paper, left=3cm, right=3cm, top=2cm]{geometry}
\title{Analysis 1}
\author{Arjihad}
%date{3 Dezember 2016}

\begin{document}

\tableofcontents
\maketitle

\section{Folgen}

\subsection{Folge, Zahlenfolgen} 
\textbf{Definition}:
Eine Folge in einer beliebigen Menge $X$ ist eine Funktion \\ \\ 
$a:\mathbb{N} \rightarrow X, \quad (a_1,a_2,a_3,...) = (a_n)_{n \geq 1} = (a_n)_n = (a_n) \\ \\ $
Man spricht von Zahlenfolgen,...

\end{document}

On the web I just found agley text frames. What i am looking for is maybe a nice green colored box with rounded corners or something like that.

Answer 1

Use tcolorbox:

\documentclass{article}
\usepackage{tcolorbox}
\usepackage{amssymb}
\tcbuselibrary{theorems}
\newtcbtheorem
  []% init options
  {definition}% name
  {Definition}% title
  {%
    colback=green!5,
    colframe=green!35!black,
    fonttitle=\bfseries,
  }% options
  {def}% prefix
\begin{document}

\begin{definition}{Titel}{label}
  Eine Folge in einer beliebigen Menge $X$ ist eine Funktion
  \[ a:\mathbb{N} \rightarrow X, \quad (a_1,a_2,a_3,...) = (a_n)_{n \geq 1} = (a_n)_n = (a_n) \]
  Man spricht von Zahlenfolgen, \dots
\end{definition}

\end{document}