Joomla + Virtuemart 3. How to change the appearance of additional product fields?

Question

Joomla

Good afternoon! There is an online store site on Joomla 3 + Virtuemart 3, and on it, for example, this page of a single product:
samogonkupit.ru/catalog/izmeritelnaya-apparatura/s...
Where it says "Measurement range" (slightly to the left of the "Add to cart" buttons ", "Buy in 1 click") - there is a bootstrap drop-down list. They ask to change it to a regular html "select" element with an arrow on the right.
The container for all this "happiness" is div class="product-field-display".
When viewing the code in the browser, this "select" can be seen - it is already embedded in the page, but it has an inline display: none, which I can’t find where it could be deleted - alas, it cannot be blocked in CSS (In the php code, the task this dirty trick is not detected. If this inline-"none" is disabled in Firebug, then the desired type of list just appears. The problem is how to disable it in "real".
(And now some creepy list built on a div with classes is active "chzn-" which should be removed on the contrary)
.