Add "null zero" to the first level of nested css counter

Here's the ordered list I have so far:

1 Item
2 Item
    2.1 Item
    2.2 Item
    2.3 Item
        2.3.1 Item
        2.3.2 Item
        2.3.3 Item
3 Item
4 Item

      

        
        
        
      

    

It is created like this:

<ol>
    <li>Item</li>
    <li>Item
    <ol>
        <li>Item</li>
        <li>Item</li>
        <li>Item
        <ol>
            <li>Item</li>
            <li>Item</li>
            <li>Item</li>
        </ol></li>
    </ol></li>
    <li>Item</li>
    <li>Item</li>
</ol>

      

        
        
        
      

    

and CSS:

ol {
    counter-reset:section;
    list-style-type: none;
}

li:before {
    counter-increment: section;
    content: counters(section, ".") " ";
}

      

        
        
        
      

    

What I want to do is make the top level items of the list "zero point" after the counter, as in

1.0 Item
2.0 Item
    2.1 Item

      

        
        
        
      

    

etc. Can this be done in CSS? This may require creative solutions.