--- title: Syntax Highlighting description: Build-time code highlighting with Tree-sitter and tree-house weight: 3 --- sukr highlights code blocks at build time using [tree-house](https://github.com/helix-editor/tree-house) (Helix editor's Tree-sitter integration). No client-side JavaScript required. ## Usage Use fenced code blocks with a language identifier: ````md ```rust fn main() { println!("Hello, world!"); } ``` ```` ## Supported Languages | Language | Identifier | | ---------- | --------------------- | | Rust | `rust`, `rs` | | Python | `python`, `py` | | JavaScript | `javascript`, `js` | | TypeScript | `typescript`, `ts` | | Go | `go`, `golang` | | Bash | `bash`, `sh`, `shell` | | Nix | `nix` | | TOML | `toml` | | YAML | `yaml`, `yml` | | JSON | `json` | | HTML | `html` | | CSS | `css` | | Markdown | `markdown`, `md` | | C | `c` | ## Examples ### Rust ```rust fn main() { println!("Hello, world!"); } ``` ### Python ```python def greet(name: str) -> str: return f"Hello, {name}!" ``` ### JavaScript ```javascript const greet = (name) => `Hello, ${name}!`; ``` ### TypeScript ```typescript function greet(name: string): string { return `Hello, ${name}!`; } ``` ### Go ```go func main() { fmt.Println("Hello, world!") } ``` ### Bash ```bash #!/bin/bash echo "Hello, $USER!" ``` ### Nix ```nix { pkgs }: pkgs.mkShell { buildInputs = [ pkgs.hello ]; } ``` ### TOML ```toml [package] name = "sukr" version = "0.1.0" ``` ### YAML ```yaml name: Build on: [push] jobs: build: runs-on: ubuntu-latest ``` ### JSON ```json { "name": "sukr", "version": "0.1.0" } ``` ### HTML ```html Hello! ``` ### CSS ```css .container { display: flex; color: #ff79c6; } ``` ### C ```c #include int main() { printf("Hello!\n"); return 0; } ``` ## How It Works 1. During Markdown parsing, code blocks are intercepted 2. tree-house parses the code and generates a syntax tree 3. Spans are generated with **hierarchical CSS classes** (e.g., `.hl-keyword-control-return`) 4. All work happens at build time—zero JavaScript in the browser ## Theme System sukr uses a **decoupled theme system** with CSS custom properties. Themes are separate CSS files that define colors for syntax highlighting classes. ### Hierarchical Scopes Highlighting uses fine-grained scope classes with hierarchical fallback: | Scope Class | Description | | --------------------------------- | --------------------- | | `.hl-keyword` | Generic keywords | | `.hl-keyword-control` | Control flow | | `.hl-keyword-control-return` | return/break/continue | | `.hl-function` | Function names | | `.hl-function-builtin` | Built-in functions | | `.hl-type` | Type names | | `.hl-variable` | Variables | | `.hl-variable-parameter` | Function parameters | | `.hl-string` | String literals | | `.hl-comment` | Comments | | `.hl-comment-block-documentation` | Doc comments | If a theme only defines `.hl-keyword`, it will apply to all keyword subtypes. ### Using a Theme Themes are CSS files that define the color palette. Import a theme at the top of your stylesheet: ```css @import "path/to/theme.css"; ``` sukr uses [lightningcss](https://lightningcss.dev/) which inlines `@import` rules at build time, producing a single bundled CSS file. ### Available Themes sukr includes several themes in the `themes/` directory: - **default.css** — Dracula-inspired dark theme (batteries included) - **dracula.css** — Classic Dracula colors - **gruvbox.css** — Warm retro palette - **nord.css** — Cool arctic colors - **github_dark.css** — GitHub's dark mode - **github_light.css** — GitHub's light mode Copy the theme files to your project and import as shown above. ### Theme Structure Themes use CSS custom properties for easy customization: ```css :root { --hl-keyword: #ff79c6; --hl-string: #f1fa8c; --hl-function: #50fa7b; --hl-comment: #6272a4; } .hl-keyword { color: var(--hl-keyword); } .hl-string { color: var(--hl-string); } /* ... */ ``` ## Injection Support Some languages support **injection**—highlighting embedded languages. For example, bash inside Nix strings: ```nix stdenv.mkDerivation { buildPhase = '' echo "Building..." make -j$NIX_BUILD_CORES ''; } ``` Markdown also supports injection—code blocks inside markdown fences are highlighted with their respective languages. Languages with injection support: Bash, C, CSS, Go, HTML, JavaScript, Markdown, Nix, Python, Rust, TOML, TypeScript, YAML. ## Fallback Unknown languages fall back to plain `

` blocks without highlighting.