The simplest way to mix Shiny and an existing web page is by using an iframe. Just like with the RMarkdown document in the previous chapter, it allows you to incorporate an entire Shiny application into an existing document, except in this case, the document is a web page rather than a Markdown document. The only restriction is that you will need to host the application somewhere on the internet so you can point to it. Once you've done that, it's as simple as just pointing to the application, like so:
<iframe src="https://chrisbeeley.net/shinyapps/shinybook3rdedition/chapter2/widgettypes/" frameborder="0" width="950" height="800"></iframe>