Building for the Web
Search, structured data, security headers and colour — the mechanics behind a page that works.
A gradient is one multiplication per channel repeated across a line. Why a gradient between two channel-opposite colours always passes through grey, and what moving a stop really changes.
Four lines go in your head and they have four different jobs — one of which is nothing. The keywords tag stopped being read by the major search engines many years ago.
JSON-LD tells a machine what a page is. It does not raise anything by itself — what it can do is make a result eligible for a richer presentation, and only if it matches what a reader can see.
The cut-off is a width in pixels, not a count of characters — so a line of wide letters runs out sooner than a line of narrow ones. Front-loading beats hitting a number.
Flesch counts sentence length and syllables, and calls that difficulty. It is a proxy — a text can score beautifully and still be incomprehensible.
Nothing the policy refuses announces itself, and a local server that sends no policy at all will look perfect right up until you deploy.
Framing, MIME sniffing, referrer leakage and forced HTTPS — four narrow jobs. Worth doing, and worth knowing exactly how narrow each one is.
A disallowed URL can still show up in search results, and the noindex tag that would keep it out only works if the crawler is allowed to fetch the page.
A 301 gets cached by browsers, sometimes with no expiry, and undoing one means reaching machines you do not control. Also: why two hops usually means one too many.
A diagonal measurement tells you almost nothing about how much surface you get, because the answer depends on the shape as well as the length. The formula, worked through at one fixed diagonal.
Pixels per inch comes from Pythagoras on the pixel grid, and it is exact arithmetic. What it cannot do on its own is describe what reaches a viewer, because that depends on distance.
The right-triangle relationship earns its keep away from the classroom: sizing a diagonal brace, checking whether something fits through an opening, and proving a corner is square before you fix it.