How to format a div like pre blocks?

If you want to get pretty fancy, consider a libraries like Pygments or highlight.js that will do full syntax coloring, in addition to pretty printing of your code.

Pygments would be implemented in server-side Python; highlight.js works browser side.

OR: use a browser-based "code editor" such as Ace, which will then format/color the code... and just use the control in a read-only fashion.

Like this

div { white-space: pre; }