Some questions regarding online payment using Bitcoin

self.Bitcoin8d ago
Can't find any answer elsewhere so decide to ask here. So I want to buy something online using Bitcoin as payment method but since I am quite new to Bitcoin, I did some research online and found out that some Bitcoin transaction may take up to 1 hour or even 1 day to complete. My questions is that let's say that I already send the Bitcoin to the seller but the seller did not receive it yet since the transaction is still pending and online checkout process mostly only have 30 min like that for you pay. In this situation, doesn't I am the one who will lose the money and receive nothing because of the transaction is still pending and seller did not receive the Bitcoin, so he/she will not confirm that I already send out the Bitcoin even though in reality I already did. Sorry if my question sound stupid or confused, I am quite new to Bitcoin and just don't want to lose my money.