I'm sure there is an obvious answer to this question, but can't seem to find it.
I'm building a custom site for a client (html/php) and need to have a web store on it. Building a web store from scratch is too daunting for me in the time I have, so I'm looking at using a prepackaged e-commerce solution like shopify, et al.
My question is whether I can use something like shopify on my site, or whether they (shopify) require you to use their website builder tool. Is it possible to only use the e-commerce tools for stuff like a cart function and checkout page without having to redesign the site or use a site builder/theme? Thanks!