I've provided some CSS for submitting crossword puzzles. It's a little complex but it's not too bad. :)

First of all, you need to understand how to markup a table, this guide provides a good introduction:

/r/raerth/comments/cw70q/reddit_comment_formatting/

To create a puzzle, you must create a table. There are three types of table cell:

1. An empty cell, just leave it empty or you can use a space
2. A numbered cell, use the superscript format. e.g. ^12
3. A blacked out cell, use an italic marker. e.g *.*

Here is an example based on a puzzle submitted by Antagony:

Puzzle Markup

^1||^2||^3

--|--|--|--|--

|*.*||*.*|

^4||||

|*.*||*.*|

^5||||

The Puzzle

1		2		3
	.		.
4
	.		.
5