MDN tool that tells you of security gaps in your website
developer.mozilla.org
developer.mozilla.org
Content Security Policy (CSP) −25
X-Content-Type-Options −5
X-Frame-Options −20
Yet it's just a simple static website without scripts, cookies or any other dynamic content. If you need to specficy whatever random heades WHATWG comes up with each year for a static site to be secure then the problem is the browser not the website.
X-Content-Type-Options is in particular is 100% about browsers ignoring the spec and then making you set another header asking them to please reconsider.
Referer is another thing that should be 100% fixed on the browser side instead of each website asking the browser to please not leak information to other websites.
Then when you look at the scoring criteria [0] you see it even avards bonus points for setting cookies and using scripts as long as you do it in the currently fashionable way comapared to not using cookies/scripts at all. This is absolutely the wrong way around.
[0] https://developer.mozilla.org/en-US/observatory/docs/tests_a...
Edit: Figured I should point out that the old one had TLS and SSH stuff also, and the URL was https://observatory.mozilla.org.
Not the same, but also very helpful for https/tls