Sentinel: Your Web-Performance Watchman

CSS Wizardry Newsletter

I maintain a small and infrequent newsletter in order to share more detailed and exclusive content with those who want it the most.

The format of the newsletter will evolve over time, but for now you should expect:

  • Exclusive content, screencasts, demos.
  • Members-only discounts for upcoming events and workshops.
  • Links to interesting articles and resources from around the web.

And you should not expect:

  • Spam. Honestly, it’s the worst.
  • Updates for the sake of updates. I will only publish when there’s something worth sharing.

Sign up

Not that fussed about email? You can still catch me on Twitter instead.

Previous Issues

  1. Issue #0001:
  2. Issue #0002:
  3. Issue #0003:
  4. Issue #0004:
  5. Issue #0005:

If you’re a product, company, or event who would like to sponsor issues of the newsletter, please do get in touch.

Hi there, I’m Harry Roberts. I am an award-winning Consultant Web Performance Engineer, designer, developer, writer, and speaker from the UK. I write, Tweet, speak, and share code about measuring and improving site-speed. You should hire me.

You can now find me on Mastodon.

Suffering? Fix It Fast!


  • inuitcss
  • ITCSS – coming soon…
  • CSS Guidelines

Next Appearance

  • Talk & Workshop

    WebExpo: Prague (Czech Republic), May 2024


I am available for hire to consult, advise, and develop with passionate product teams across the globe.

I specialise in large, product-based projects where performance, scalability, and maintainability are paramount.