HI Alex,
Thanks for your reply, this site is on my local machine. I probably can't provide web address. but I did what you said:
1. use Inspect this element, this is what page show:
<div class="category-description">
<table style="width: 100%; padding: 0px; margin: 0px; border: 0px;" border="0">
<tbody>
<tr>
<td><img style="width: 100%;" src="/var/theme/images/banner-1.png" alt=""></td>
<td><img style="width: 100%;" src="/var/theme/images/banner-2.png" alt=""></td>
<td><img style="width: 100%;" src="/var/theme/images/banner-3.png" alt=""></td>
</tr>
</tbody>
</table></div>
2. make new css in customer css:
#category-description{
border:0px
}
is this what you mean?