The English Premiership Football example: here uses <Style> and <IconStyle> as well as inline styles.
You want something like:
Code:
<Style id='LINKED_STYLE_ID'>
<IconStyle><Icon><href>URL GOES HERE ....</href></Icon>
<hotSpot x="16" y="32" xunits="pixels" yunits="pixels"/>
</IconStyle>
</Style>
<Placemark>
<name>Name</name>
<description><![CDATA[<div >HTML Description</div>]]></description>
<Point><coordinates>-2.96632468700409,53.438828522666,0</coordinates></Point>
<styleUrl>#LINKED_STYLE_ID</styleUrl>
</Placemark>
The HTML and JavaScript are basically a copy of the Playground Example