Hi,
The HTML of your customized version is not valid.
For example, you have:
<table style="float: left !important; text-align: left !importannt;">
<table class="w600" border="0" cellspacing="0" cellpadding="0" width="600" style="margin:0px;font-family: Arial, Helvetica, sans-serif;font-size:12px;line-height:18px;float: left !important; text-align: left !importannt;">
So two table tags, one inside the other.
That's not valid HTML.
Another example is this:
<strong>Thank you for choosing to shop at Astore</strong> <br/>
Astore – the Autodesk and BIM software online store operated by Forida Limited<br/><br/>
</table>
</p>
</div>
You have a closing table and a closing p tag without thei opening tag counterparts before.
If your HTML is not valid it will probably break the layout, like it does in your screenshot.
Note that, between a browser displaying the HTML of a web page, and an email client displaying the HTML of an email, they don't interpret the HTML the same way, even more so when the HTML is invalid. So it's probably why you don't get the same result.