Does anyone know how to position a hyperlink box on a web banner to be position-specific to pixels as opposed to 'left' or 'right'?

I need to change the position of a box that has a hyperlink that takes me to order a product. The code that is currently producing the web banner is as follows:

...

<img src="assets/file/home-page-slider/gofogwebbanner.png" width="1470" height="380" border="0" usemap="#map" />
<map name="map">
<div class="banner-text-03-left"><a class="home-slider-button" href="products/anti-viral-room-fogger-200ml-canister" title="Order now">Order now</a></div>
...

I know that I can change the 'left' to be 'right' and that moves my hyperlink box to the right side of the banner, but I would live to place it, preferably to the pixel if I could, around the middle bottom of the banner.

NOTE: I am working on QVS3 and I am editing our live website that is already built. A link to the website is here and the banner in question is the 'GoFog' ad on the first banner slide when you visit the website. Link: https://www.ehmltd.co.uk/

I am sure this is like ABCs to someone who has the know-how, but it is proving difficult for me at the minute. Any help would be appreciated! I will reply pretty much instantly to all/any help I can get, so feel free to ask me questions if you need more info.