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Mozilla Developer Channel

Videos, articles, & tools for web professionals

We worked with Mozilla Developer Relations to research & address developer needs around open web standards, CSS features, accessibility, Firefox, and developer tools. Over the course of six months, we released 30 videos to nearly twenty thousand subscribers.

What We Did

Mozilla Developer YouTube channel with 24.3K subscribers
      and a grid of videos


  • Research
  • CSS & Firefox DevTooling Tutorials
  • Developer Relations

Languages & Tools

  • CSS
  • Firefox
  • 4K screen and video recording

Are you following @TerribleMia yet? She’s amazing. I’m so lucky to get to work with her on this video series & more.

@TerribleMia does not only explain “why CSS is how it is” but also neatly summarizes the basic principles of what make the Web the Web. If you know those principles, many implementation details will be less baffling to you.

Two of the most popular videos from Miriam. Check out the posts below for links to the rest…

2019 Posts

  1. Firefox Developer Tools
    Video post type

    Edit CSS Shapes in the Browser

    For quick visual adjustments directly on the page

    Have you ever wanted to create more interesting shapes on the web, or flow text around the details of an image? Shape paths can be hard to code without a visual reference, but Firefox provides a shape editor to make it quick and clear.

    see all Video posts
  2. CSS @supports statement
    Video post type

    Use new selectors responsibly with selector queries

    Just in time for Selectors Level 4

    Firefox 69 was the first to implement selector feature queries, but other browsers are following suit. I’ll show you how it works, and how to start using this new feature query right away.

    see all Video posts
  3. CSS code snippet with overflow wrap options
    Video post type

    How do you wrap long words in CSS?

    None of the solutions are perfect, but we have some options

    Horizontal text overflow has always been difficult to manage on the web. The default visible overflow is designed to make sure content remains accessible no matter the size of a containing box, but it’s not our only option.

    see all Video posts
  4. CSS code snippet of scroll-snap type and align
    Video post type

    Scroll Snap in CSS

    Without any JavaScript or “scrolljacking”

    When we’re scrolling down a page, or through a gallery of images, snap-targets can help guide us from one section or image to the next. In the past, developers have used JavaScript to hijack scrolling, but now we can manage scroll alignment directly in CSS with only a few lines…

    see all Video posts
  5. CSS snippet showing display value options
    Video post type

    Inner & Outer Values of the Display Property

    Allow us to be more explicit & expressive about layouts

    The display property has been in CSS from the beginning, handling everything from block and inline boxes to list-items and full layout systems like flexbox or grid. Now the display syntax is getting an upgrade to match it’s multiple uses.

    see all Video posts
  6. Firefox Developer Tools shows helpful information about inactive CSS
    Video post type

    Why isn’t this CSS doing anything?

    Have you ever set a width in CSS, and… nothing happens?

    There are a number of property & value combinations that can lead to CSS being inactive, and now Firefox will tell you why. Open the developer tools, and look for the greyed-out property with an info-box on hover.

    see all Video posts
  7. Inspecting grid with Firefox Developer Tools
    Video post type

    Faster Layouts with CSS Grid

    And subgrid, landing on Dec 3

    For years, we’ve struggled to build resilient layouts on the web, but CSS Grid promises to change all that – and you can start using it now, with only a few properties and basic concepts.

    see all Video posts
  8. CSS Snippet for CSS subgrid to make forms
    Video post type

    Laying out Forms using Subgrid

    and fallbacks for legacy browsers

    It’s a common pattern to align form labels and inputs in grid-like layout. I’ll show you how to do it quickly using CSS subgrid, with several quick fallbacks.

    see all Video posts
  9. CSS snippet with card layout demo
    Video post type

    Subgrid for Better Card Layouts

    and fallbacks for legacy browsers

    Card layouts are popular on the web, rows and columns of boxes with similar content. CSS grids can help align those cards, but it’s still be hard to line-up content inside the cards – headers and footers that might need more or less room.

    see all Video posts
  10. CSS snippet showing display revert
    Video post type

    What does revert do in CSS?

    And how is it different from unset or initial?

    I’ve often used initial and unset in my CSS – global keywords that can be applied to any property. The difference is small, but important: unset allows inheritance, while initial does not. But then Firefox implemented revert and I was confused – how is this one different from the others?

    see all Video posts
  11. CSS cascade diagram
    Video post type

    Why is CSS so Weird?

    How can we design for an unknown & infinite canvas?

    CSS is the design language of the web – one of three core web languages – but it also seems to be the most contentious and often perplexing. It’s too easy and too hard, too fragile and too resilient. Love it or hate it, CSS is weird: not quite markup…

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  12. Lists styled with cat emojis
    Video post type

    Styling Lists in CSS

    Powerful New CSS for Styling Bullets, Numbers, and List Markers

    When you create lists in HTML, browsers add bullet-points or numbers we call list markers. Now CSS gives us the tools to style those list markers, and even create our own!

    see all Video posts
  13. Video post type

    Announcing the Mozilla Developer Channel

    a gift from Mozilla (and OddBird)

    Over the summer, we’ve been working with Mozilla to help create a new resource for web professionals like us – with a mix of videos, articles, demos, and open source tools. Today, we’re excited to launch the video channel!

    see all Video posts