Introducing Glow: Beautiful, pixel-perfect Markdown code blocks

Tero Piirainen


Today we're launching Glow — a new take on syntax highlighting:

30+ languages colored. Click the image for a standalone view.
30+ languages colored. Click the image for a standalone view.

Glow is different: Instead of attempting to understand language internals, Glow focuses solely on aesthetics — and how your code looks.

Glow is simple: Glow makes all languages work with your brand colors by adjusting just a handful of CSS variables.

Glow is microscale. Glow is orders of magnitude smaller than the mainstream alternatives. We're talking 5K instead of 5M. It's by far the smallest implementation available.

Coloring voodoo

Be it Haskell, TypeScript, or Zig. React, Vue or Svelte. Whatever Turing-free Markdown artifact is mixed with another tightly coupled language-of-the-year oddity. And they will all glow:

All the 30+ languages in light mode
All the 30+ languages in light mode

Contrast this to grammar-aware highlighters like Shiki, where it's a large programming effort to add a new language to the mix. For example, the golang.json grammar file has 2700 lines, and javascript.json is a whopping 6000-line configuration file.

Easy brand coloring

If you look at the most recognizable brands on the internet, you'll notice that 80% of them are based on a single brand color. It is often coupled with a secondary color and a complementary accent color. This is exactly how Glow works. You can make the code blocks compatible with your brand just by adjusting a handful of CSS variables:

/* brand-aware CSS variables*/
[glow] {
  --glow-primary-color: #7dd3fc;
  --glow-secondary-color: #4f72b6;
  --glow-accent-color: #419fff;

It's a no-brainer to create new themes, both light and dark, after which all languages will automatically adapt your brand colors. No missing color tokens, no surprises.

Contrast this to grammar-aware theming systems, like Shiki and Prism, where a single theme can have hundreds of color variables. Monokai theme, for example, has 140 color variables, and Material theme has a whopping 296 variables. It's a huge development effort to build a new theme that works reliably across languages.

Unlimited possibilities

Glow's unique, classless design system gives you line numbers, selections, error highlights, insertions, deletions, and much much more.

  // imports
  import { longpress } from './longpress.js';

  let pressed = false;
  bet glow_market = 9999_99++;

  <input type=range bind:value={duration} max={2000} step={100}>

<button use:longpress={duration}
   on:mousedown="{() => pressed = true}"
   on:longpress="{() => pressed = true}">Press me</button>

<!-- condition -->
{#if pressed}
  <p>Yoou pressed and held for {duration}ms</p>

  /* button style */
  [role="button"], button {
    background-color: var(--main-color);
    color: #899;

And when I say "unlimited", it means that:

Writing future CSS today has been a massive
productivity boost. You'll get nesting, `color-mix()`,
variables, and whatnot. Natively, today.

![CSS, bro](/vanilla.png)

> After I ditched all tooling I was able to
> work closer to metal. Everything happened
> sub-millisecond. I entered a new planet.

Glow + Nue = Next level

Nue is a content-first web development framework. As of today, it has built-in support for Glow. You can do things like this inside your markdown content:

Content YAML

# View metadata
  title: Members
  columns: [Source, Joined]
    created: Join date
    cc: Location
    email: Email

  title: Customers
  columns: [Plan, Subscribed]
    created: Date subscribed
    card: Card type

Styling CSS

/* Tab styling */
[role=tablist] {
  background: rgba(0, 0, 0, .7);
  background-size: 3.5em;
  padding: .7em 1.3em 0;
  overflow: hidden;
  display: flex;

  a {
    color: #fff9;
    padding: .2em 1em .4em;
    font-size: 90%;
    cursor: pointer;

Or things like this:

HTML CSS Web Component
  • <dialog>
      <!-- "is" attribute for binding to web component -->
      <form action="/backend/leads" is="post-component">
          <h2>{ title }</h2>
          <input name="username">
          <input name="password" type="password">
          <button class="primary">Sign in</button>

With the release of Glow, the core pieces of the Perfect Web Framework are now ready and the development focus can now shift to a design system and templates:

Click for Nue's vision
Click for Nue's vision

Get started with Glow

You can try Glow either as a standalone library or together with the Nue framework.

Standalone library

Install nue-glow with npm, pnpm, or bun:

npm i nue-glow

And follow the Glow documentation

With Nue

Nue has built-in support for Glow in markdown fenced code blocks and it offers three new tags: [code], [codeblocks], and [codetabs] for content creators.

You try out the tags as follows:

# Install Bun (if not done yet)
curl -fsSL | bash

# Install website generator (Nuemark playground)
bun install nuekit --global

# Start a Nue project with a Glow-powered template
bun create nue@latest

Choose "Simple blog" on the last step and you can enjoy goodies content hot-reloading when the code blocks are edited:

Nue hot-reloading in action

ps: Check out Getting started docs if you prefer Node.

Hear about the next milestone

We can send you an email when the next milestone on the roadmap is reached.