Currently my menu-navigation in WordPress looks like this:

```
<ul>

<li class="cat-item cat-item-1">
<a href="http://website/food/pizza/">Pizza</a>
</li>

<li class="cat-item cat-item-3">
<a href="http://website/food/snacks/">Snacks</a>
</li>

</ul>

```

Is there any posibility to add some code to functions.php, so I will get this?:
(remove "<http://website/food/>", then add # before slug)

```
<ul>

<li class="cat-item cat-item-1">
<a href="#pizza">Pizza</a>
</li>

<li class="cat-item cat-item-3">
<a href="#snacks">Snacks</a>
</li>

</ul>

```

I tried some code with:

```
add_filter( 'wp_list_categories', 'filter_categories' );

function filter_categories( $html ) {
  ...preg_replace...
}

```

But with no luck...

Can someone please help me out?
Thanks in advance!