Here are a few issues and recommendations

[prakshark]

1. The subtotal is not summing up the cost of all products, only the first one.
2. I recommend adding a tax section, to add a percentage of the subtotal to the total cost.
3. Though this is not important, I recommend having a dark mode toggle button on the top right corner of the page.

PS: If you would like to have these, do comment and I'll work upon these features, and you may merge the PR. I am not starting the work right away coz I saw their are multiple issues raised and not attended yet, So I think this repo is unattended.