pub fn root(mut self, val: &str) -> Self {
        self.root = val.to_string();
        self
    }
Sets the HTML ID of the `<div>` element at which to insert Perseus.
In your index view, this should use [`PerseusRoot`].

*Note:* if you're using string HTML, the `<div>` with this ID MUST look
*exactly* like this: `<div id="some-id-here"></div>`, spacing and
all!
packages/perseus/src/init.rs