Nested menus in Mobi

Question

I've created an epub that works great. It has daily meditations, for a total of 366. In my epub, the TOC is nested, so if I want to go to October 15, I click on October, the dates expand out 1 - 31, then I click on 15. When I converted it to Mobi, however, on my Kindle the TOC is like:

January
1    
2
3
4
.
.
.
February
1
2
3
4
.
.
.
and so on to Dec 31.  

How do I fix my menu to be nested like the epub?

So far everything else is looking fine on the mobi.

Answer 1

The Amazon Publishing Guidelines has sample code for making a nested html TOC.

It's on page 16

<div>Section 1</div> 
<div style="margin-left:2%;">Chapter 1</div> 
<div style="margin-left:2%;">Chapter 2</div> 
<div style="margin-left:2%;">Chapter 3</div> 
<div style="margin-left:4%;">Subchapter 1</div> 
<div style="margin-left:4%;">Subchapter 2</div> 
<div style="margin-left:2%;">Chapter 4</div> 
<div style="margin-left:4%;">Subchapter 1</div> 
<div>Section 2</div> 
 ... 

Now here's an alternate way to do the same thing:

<style> div.chapter { margin-left: 1em} 
 div.subchapter { margin-left: 2em} </style> 
<div>Section 1</div> 
<div class="chapter">Chapter 1</div> 
<div class="chapter">Chapter 2</div> 
<div class="chapter">Chapter 3</div> 
<div class="subchapter">Subchapter 1</div> 
<div class="subchapter">Subchapter 2</div> 
<div class="chapter">Chapter 4</div> 
<div class="subchapter">Subchapter 1</div> 
<div>Section 2</div> ...

I've never tried it, but I assume it will work.

Also, I found another working example for nested TOC in the book EPUB3 Best Practices by Matt Garrish and Markus Gylling. The code they used depending on very sophisticated CSS for the NAV element. I'm guessing that this is only an EPUB solution and wouldn't work for the Kindle.

FURTHER THOUGHTS: It's not mentioned in the Amazon Publishing Guidelines, but I assume that all of this html is inside the <nav epub:type="toc"> element (leading me to wonder why the elements here are all DIVs instead of LIs).