Hi, thanks for the help
I seem to have resolved it by playing around and putting the header line into a paragraph
so
<li id="id_Toc78976220" class="block_12"><span class="text_15">The Human Body</span></li>
becomes
<p li id="id_Toc78976220" class="block_12"><span class="text_15">The Human Body</span></li></p>
It then shows in Amazons kindle previewer correctly without the indent on the header