Hi,
You have these translations around the price without taxes:
PRICE_BEFORE_TAX=" ("
PRICE_AFTER_TAX=" excl VAT) "
So you could use translation overrides to add an HTML element around it.
For example:
PRICE_BEFORE_TAX=" <span class='price_without_tax'>("
PRICE_AFTER_TAX=" excl VAT)</span> "
So you can use .hikashop_product_price .price_without_tax to target the price without taxes.
For example:
/* price with taxes will be red */
.hikashop_product_price{ color: red; }
/* price without taxes will be blue */
.hikashop_product_price .price_without_tax{ color: blue; }
More information on translation overrides:
www.hikashop.com/download/languages.html#modify