Hi,
First, I would recommend you to remove the CSS rule
.hikashop_product_main_image_thumb img {
width: 350px !important;
height: 230px !important;
align: left;
}
from your custom frontend css.
If you want to change the size of the thumbnail, you can change the "Product page image width/height" in the "System > Configuration > File > Images " section.
About your product show view question.
You have to edit the view "product | show_default" for the template "siteground-j16-7".
In this view, you would find this code
<div id="hikashop_product_description_main" class="hikashop_product_description_main">
<?php
//DISPLAY the product description
echo JHTML::_('content.prepare',preg_replace('#<hr *id="system-readmore" */>#i','',$this->element->product_description));
?>
</div>
which display the product description in the page.
Regards,