Archival acid-free paper -- paper with cotton added to it -- can last up to 1000 years, but be prepared to pay $2.50 for 1 page[1], so a 400 page book will cost you $1000 for one copy, just for the paper in the book. This type of archival paper might be useful for important contracts or deeds, or legal documents.
But then you have to worry about ink. Normal ink will break down as well in 1-200 years, so you need archival ink. This boils down the difference between pigment and dye based inks. Dye based inks are more expensive but more resistant to UV light.
In the end, light, heat, water, will destroy everything.
The way to make something last is social in nature -- building long lasting institutions and cultures that value your website and archive it. These must be able to preserve themselves, which means traditions that forcefully apply to successive generations.
It is not a technological problem, but a social problem. However liberalism is completely unequipped to solve this problem, because in order to create something that outlives you, you must bind future generations to some course of action they haven't agreed upon yet. So a liberal society cannot have long lasting institutions or traditions, it always eats itself -- there is another trending hackernews topic about Jefferson being cancelled. Well, of course Jefferson will be cancelled. So will Martin Luther King. So will everyone else. Absolutely nothing can last in a liberal society that believes moral progress is possible -- e.g. that children can be more moral than their grandparents. If you look at durable societies of the past, they all believed that the grandparents were wiser and more moral than they. That allowed them to preserve traditions and texts. The contingent that believes the opposite does not preserve texts, they burn them/cancel them/or otherwise try to erase them.
So once you stop thinking in terms of "what is the best way to do X" to "what is the best way to make sure my mechanisms of doing X will last", then you end up with completely different solutions for the same problem, because the social technologies of preservation are often the exact opposite of the social technologies of progress and improvement.
So no, your website is not going to last 500 years.