Touch Help wit xhtml in CSS

Hi,
Please, I need help to properly define a list style. The issue is as follows:

1. define a list style in CSS, for example: ol.dec { list-style-type: decimal; }
2. in xhtml document I use the style defined above, for example:
<ol class="dec">
<li> blablablabla </ li>
other ....
<li> blablablabla </ li>
</ ol>

And it works perfectly. But..., only it works "perfectly" to the item number 9. Starting with item 10 does not present the full decimal number.
The number 10 to 19, has only 1. blablablabla ...
The number 20 to 29, has only 2. blablablabla ...
etc.

Firmeware is a problem in the Kobo Touch? I'm missing something in the CSS code?

Can anyone suggest me a solution? Beforehand very grateful.

Kobo Touch N905C, firmware 2.6.1b
Spanish language.