thumbnails way too small

-- url of the page with the problem -- : www.odysseybatteries.co.nz/hikashop-menu.../7-Odyssey-25-PC1400
-- HikaShop version -- : 4.0.1
-- Joomla version -- : 3.9.2
-- PHP version -- : 7.1.21
-- Browser(s) name and version -- : Chrome, Mozilla

Read the forum guides changed the custom css front end file

img.hikashop_child_image {
margin:2px;
height:120px;
}

Still doesn't change anything, I'm a newbie so what else have I missed?

Hi,

If you check the HTML/CSS of that page with your browser"s developer tools you can see that you kept the CSS by default from HikaShop and only added yours but yours is added before HikaShop's default one:
monosnap.com/file/AVAcyWu8tc1mJuEbaKdTOO8HkTWGTE
So if you want to take the priority in your CSS, you need to use !important in your CSS.