Page head and SEO

Several headmatter keys shape the page's <head>:

---
title: My talk
titleTemplate: '%s | Conf 2026'
info: |
  ## About this talk
author: Ada
keywords: [angular, slides]
lang: en
favicon: /favicon.ico
htmlAttrs: { data-theme: x }
seoMeta:
  ogImage: auto
  ogUrl: https://example.org/talk
---

Key	Effect
title, titleTemplate	The browser tab. %s is the title.
info	Markdown for the info dialog. Without markup, up to 300 characters, it is also the page description.
author, keywords	Meta tags. keywords is a list or a comma separated text.
lang, htmlAttrs	Attributes on <html>.
favicon	A file of public/, or a web address.
seoMeta	Open Graph and Twitter tags: ogTitle, ogDescription, ogImage, ogUrl, twitterCard and so on.

seoMeta.ogImage is a web address, auto (a screenshot of slide 1 made by the build, 1470 x 828, written as og-image.png), or left out: an og-image.png next to slides.md is then copied and used. Crawlers need a full address, so set seoMeta.ogUrl to the public address of the deck.

auto needs a Chromium at build time.