Paths in a URL aren't actually accessing files on a hard drive. They're sending a request to a program to serve the client the content defined by the path. Many times, said "server" program then goes and looks at a path on its host drive and serves a file there, but that is by no means a requirement - it's just a string that serves as an identifier.
In this case, the content served in response to the identifier "/static/style.css" can very easily (and according to the author, is) baked directly into the (single) binary.
Maybe. Seems odd that they'd use a vestigial 'static' directory in the request path, though. I didn't read it because the layout makes it useless on mobile browsers, but I have a feeling they mean that the whole site is coded into one binary like a self-contained ssg rather than the site only requiring one file to work.
Because that means every page request downloads all the static content. It’s generally nice for people if they only have to download the shared assets once.
The stylesheet is just under 3KB even with no minification or compression. At that size, the cost is negligible, and inlining will consistently be faster to load even than a warm cache of an external stylesheet. In most conditions, you’ve got to get towards 100KB before it even becomes uncertain. Loading from cache tends to be surprisingly slow, vastly slower than most people expect. (Primary source: non-rigorous personal experimentation and observation. But some has been written about how surprisingly slow caches can be, leading to things like some platforms racing a new network request and reading from disk, which is bonkers.)
Seriously, people should try doing a lot more inlining than they do.
I think it depends on how you set your cache? If it’s not configured to re-check with the server it may be much faster.
Then again, for 3KB the overhead of doing a cache check after parsing the HTML for the first time and then rendering it again may already be too much :)
Exactly. Inline is just surprisingly much faster than a lookup by URL, which has to check “do I have this cached? What type (immutable, revalidate, &c. &c.)? Now (if suitable) fetch it from the cache.” before it can get on with actually acting on the resource’s contents.
In this case, the content served in response to the identifier "/static/style.css" can very easily (and according to the author, is) baked directly into the (single) binary.