# Enumerate environment aligning incorrectly (all flushed left)

I have generated a minimal working example of an issue I'm having. I'm simple writing in an article document type, and for some reason the enumerate environment is flushing left. I would like it to be normally indented relative to the surrounding text.

Below is the offending code and a picture of what it looks like.

\documentclass{article}
\usepackage{amsmath}
\usepackage{geometry}
\geometry{legalpaper, portrait, margin=1in}
\usepackage{amssymb}

\begin{document}
\section{Fermat's Little Theorem using Group Theory}

Fermat's Little Theorem (1637): For any integer $n$ and prime $p>n$, $n^p\equiv n\,(\mod p)$.

\vspace{2mm}

Two preliminary theorems:

\begin{enumerate}
\item[1. Bezout's Identity:] Let $a,b\in\mathbb{Z}$ (but not both zero) and $d=\gcd (a,b)$. There always exists at least one pair of integers $(x,y)$ such that:

$$ax+by=d$$

\item[2. Lagrange's Theorem]: For any finite group $G$ and subgroup $H$, the order of $H$ divides $G$, i.e. $[G]=k[H]$ for some $k\in \mathbb{Z}_+$.
\end{enumerate}
\end{document}


This is due to the use of very long item labels. You should eventually use the description environment like it is (very well) described in this post.

You're abusing enumerate and also colons (but the latter is a stylistic remark).

You want a description, instead.

I also made a few TeX correction:

1. there is no need for \vspace{2mm};
2. there must never be a blank line before a displayed formula;
3.  should never be used in LaTeX.

The mathematical corrections:

1. the restriction that a and b are not both zero is redundant;
2. the restriction that p > n is likewise redundant.

Fixed code.

\documentclass{article}
\usepackage{amsmath}
\usepackage{geometry}
\usepackage{amssymb}

\geometry{legalpaper, portrait, margin=1in}

\begin{document}
\section{Fermat's Little Theorem using Group Theory}

\textbf{Fermat's Little Theorem (1637).} For any integer $n$ and
prime $p$, $n^p\equiv n\pmod{p}$.

Two preliminary theorems.

\begin{description}
\item[1. Bezout's Identity.] Let $a,b\in\mathbb{Z}$ and $d=\gcd (a,b)$.
There exists at least one pair of integers $(x,y)$ such that
$ax+by=d$

\item[2. Lagrange's Theorem.] For any finite group $G$ and subgroup $H$,
the order of $H$ divides $G$, i.e. $[G]=k[H]$ for some $k\in \mathbb{Z}_+$.
\end{description}

\end{document}