dioxus_style 0.2.0

Scoped CSS styling system for Dioxus components with compile-time processing
Documentation

dioxus_style

Scoped CSS styling for Dioxus components - Write CSS that's automatically scoped to your components, preventing style conflicts and maintaining clean, modular code.

Crates.io Documentation License

Features

  • 🎯 Automatic CSS Scoping - Classes, IDs, and elements are automatically scoped
  • 🏷️ Element Scoping - Element selectors (div, span) use data attributes for isolation
  • 📦 File or Inline CSS - Load from .css files or write inline
  • ⚡ Zero Runtime Overhead - All processing happens at compile time
  • 🔥 Hot Reload Support - CSS changes are tracked via include_str!
  • 🎨 Multiple Macro Options - Choose the syntax that fits your style
  • 🚀 Performance Optimized - Fast hashing (xxHash), efficient parsing, and minification in release builds
  • 💾 Global Style Registry - Automatic deduplication and insertion order preservation

Quick Start

Add to your Cargo.toml:

[dependencies]

dioxus_style = "0.2.0"

Usage Examples

1. Attribute Macro with Auto-Injection (Recommended)

The simplest way - styles are automatically injected:

use dioxus::prelude::*;
use dioxus_style::with_css;

#[with_css("button.css")]
fn Button() -> Element {
    rsx! {
        button { 
            "data-scope": "{css}",
            class: "{css}_btn", 
            "Click me!" 
        }
    }
}

button.css:

.btn {
    background: blue;
    color: white;
    padding: 10px 20px;
    border-radius: 5px;
}

.btn:hover {
    background: darkblue;
}

button {
    cursor: pointer;
    border: none;
}

2. Manual Style Management

For more control over when styles are injected:

use dioxus::prelude::*;
use dioxus_style::{scoped_style, inject_styles};

#[component]
fn Card() -> Element {
    let css = scoped_style!("card.css");
    
    rsx! {
        style { dangerous_inner_html: "{inject_styles()}" }
        div { 
            "data-scope": "{css}",
            class: "{css}_card",
            h2 { 
                "data-scope": "{css}",
                class: "{css}_title", 
                "Hello" 
            }
            p { 
                "data-scope": "{css}",
                class: "{css}_content", 
                "World" 
            }
        }
    }
}

3. Inline CSS

No external file needed:

use dioxus::prelude::*;
use dioxus_style::css;

#[component]
fn Badge() -> Element {
    let css = css!("background: red; color: white; padding: 4px 8px;");
    
    rsx! {
        span { 
            "data-scope": "{css}",
            class: "{css}", 
            "New" 
        }
    }
}

4. Function-like Component Macro

Alternative syntax for defining styled components:

use dioxus::prelude::*;
use dioxus_style::component_with_css;

component_with_css! {
    css: "card.css",
    fn Card() -> Element {
        rsx! {
            div { 
                "data-scope": "{css}",
                class: "{css}_card", 
                "Content" 
            }
        }
    }
}

How It Works

Compile-Time Processing

let css = scoped_style!("button.css");
// Generates: "sc_a1b2c3d4"

Input CSS:

.btn { color: red; }
.btn:hover { color: blue; }
div { margin: 10px; }
#header { font-size: 24px; }

Output (scoped):

.sc_a1b2c3d4_btn { color: red; }
.sc_a1b2c3d4_btn:hover { color: blue; }
div[data-scope="sc_a1b2c3d4"] { margin: 10px; }
#sc_a1b2c3d4_header { font-size: 24px; }

Usage in Components

// Use the scoped class name and data-scope attribute
button { 
    "data-scope": "{css}",
    class: "{css}_btn", 
    "Click" 
}
// Renders: <button data-scope="sc_a1b2c3d4" class="sc_a1b2c3d4_btn">Click</button>

Scoping Behavior

What Gets Scoped

Selector Type Input Output Usage
Class .btn .sc_xxx_btn class: "{css}_btn"
ID #header #sc_xxx_header id: "{css}_header"
Element div div[data-scope="sc_xxx"] "data-scope": "{css}"
Pseudo-class .btn:hover .sc_xxx_btn:hover (automatic)
Complex .card > .title .sc_xxx_card > .sc_xxx_title (automatic)

Element Scoping (New in v0.2.0)

Elements are scoped using data-scope attributes:

// CSS
div { padding: 20px; }
span.highlight { color: yellow; }

// Component
rsx! {
    div { 
        "data-scope": "{css}",
        class: "{css}_container",
        span { 
            "data-scope": "{css}",
            class: "{css}_highlight",
            "Text"
        }
    }
}

Style Injection Strategies

Auto-Injection (Recommended for Simple Cases)

#[with_css("styles.css")]
fn MyComponent() -> Element {
    // Styles automatically injected - no manual inject_styles() needed
    rsx! { 
        div { 
            "data-scope": "{css}",
            /* your content */ 
        } 
    }
}

Manual Injection (Recommended for Root Component)

#[component]
fn App() -> Element {
    rsx! {
        // Inject ALL registered styles once at the root
        style { dangerous_inner_html: "{inject_styles()}" }
        
        // Your components
        MyComponent {}
        AnotherComponent {}
    }
}

Advanced Features

CSS File Path Resolution

The library searches for CSS files in multiple locations:

scoped_style!("button.css")
// Searches:
// 1. ./button.css
// 2. ../button.css
// 3. ../../button.css
// 4. src/button.css

Complex Selectors

All complex selectors are fully supported:

/* Child combinator */
.parent > .child { color: blue; }
/* Output: .sc_xxx_parent > .sc_xxx_child { color: blue; } */

/* Adjacent sibling */
.card + .card { margin-top: 20px; }
/* Output: .sc_xxx_card + .sc_xxx_card { margin-top: 20px; } */

/* Mixed selectors */
div.container > span#label { font-weight: bold; }
/* Output: div[data-scope="sc_xxx"].sc_xxx_container > span[data-scope="sc_xxx"]#sc_xxx_label { font-weight: bold; } */

/* Pseudo-classes */
button:hover:active { transform: scale(0.95); }
/* Output: button[data-scope="sc_xxx"]:hover:active { transform: scale(0.95); } */

Minification

In release builds, CSS is automatically minified:

// Debug: Preserves formatting for readability
// Release: Removes whitespace and comments for smaller bundles

Hash Generation

Uses xxHash (XXH3) for fast, collision-resistant hashing:

// Hash includes file path + content for uniqueness
// Format: "sc_" + base62(hash)
// Example: "sc_3xK9mP2"

Performance Characteristics

  • Compile-time processing: Zero runtime CSS parsing
  • O(1) style lookups: HashMap-based registry
  • Deduplication: Identical styles registered only once
  • Fast hashing: xxHash3 is one of the fastest non-cryptographic hashes
  • Efficient scoping: Single-pass CSS transformation with optimized state machine

Architecture

┌─────────────────────────────────────┐
│  Your Component (compile time)      │
│  scoped_style!("button.css")        │
└──────────────┬──────────────────────┘
               ↓
┌─────────────────────────────────────┐
│  Procedural Macro                    │
│  • Read CSS file                     │
│  • Generate hash (xxHash3)           │
│  • Scope selectors:                  │
│    - .btn → .sc_xxx_btn              │
│    - #id → #sc_xxx_id                │
│    - div → div[data-scope="sc_xxx"]  │
│  • Minify (release builds)           │
└──────────────┬──────────────────────┘
               ↓
┌─────────────────────────────────────┐
│  Runtime Registry (lazy_static)      │
│  • Store scoped CSS                  │
│  • Deduplicate by hash               │
│  • Preserve insertion order          │
└──────────────┬──────────────────────┘
               ↓
┌─────────────────────────────────────┐
│  inject_styles() → <style> tag       │
│  • Inject into DOM                   │
│  • All styles in single tag          │
└─────────────────────────────────────┘

Examples

Complete App Structure

use dioxus::prelude::*;
use dioxus_style::{with_css, inject_styles};

fn main() {
    dioxus::launch(App);
}

#[component]
fn App() -> Element {
    rsx! {
        style { dangerous_inner_html: "{inject_styles()}" }
        Header {}
        Main {}
        Footer {}
    }
}

#[with_css("header.css")]
fn Header() -> Element {
    rsx! {
        header { 
            "data-scope": "{css}",
            class: "{css}_header",
            h1 { 
                "data-scope": "{css}",
                "My App" 
            }
        }
    }
}

#[with_css("main.css")]
fn Main() -> Element {
    rsx! {
        main { 
            "data-scope": "{css}",
            class: "{css}_container",
            Card { title: "Welcome" }
        }
    }
}

#[with_css("card.css")]
fn Card(title: String) -> Element {
    rsx! {
        div { 
            "data-scope": "{css}",
            class: "{css}_card",
            h2 { 
                "data-scope": "{css}",
                class: "{css}_title", 
                "{title}" 
            }
        }
    }
}

Scoping Rules Summary

✅ Automatically Scoped

  • Classes: .button → .sc_xxx_button
  • IDs: #header → #sc_xxx_header
  • Elements: div → div[data-scope="sc_xxx"] (requires data-scope attribute)
  • Pseudo-classes: :hover, :focus, :active, etc.
  • Pseudo-elements: ::before, ::after
  • Attribute selectors: [type="text"] (passed through, element gets scoped)
  • Complex selectors: All combinators (>, +, ~, space)

❌ Not Scoped (Global)

  • Universal selector: *
  • :root: CSS variables at root level
  • @keyframes: Animation definitions (use unique names)
  • @media, @supports: Query blocks (contents are scoped)

Migration from v0.1.0

Breaking Changes in v0.2.0

  1. Element selectors now require data-scope:

    // OLD (v0.1.0) - elements were not scoped
rsx! { 
    div { class: "{css}_container", "Content" } 
}

// NEW (v0.2.0) - add data-scope
rsx! { 
    div { 
        "data-scope": "{css}",
        class: "{css}_container", 
        "Content" 
    } 
}

  2. Class selector output format changed:

    • Old: .sc_xxx.button
    • New: .sc_xxx_button

  3. ID selector output format changed:

    • Old: #sc_xxx.header
    • New: #sc_xxx_header

Troubleshooting

CSS file not found

// ❌ Error: Failed to find CSS file 'button.css'
scoped_style!("button.css")

// ✅ Solution: Use relative path from Cargo.toml location
scoped_style!("src/components/button.css")

Styles not appearing

// ❌ Forgot to inject styles
#[component]
fn App() -> Element {
    rsx! { MyComponent {} }
}

// ✅ Add inject_styles() to root component
#[component]
fn App() -> Element {
    rsx! {
        style { dangerous_inner_html: "{inject_styles()}" }
        MyComponent {}
    }
}

Element styles not working (v0.2.0)

// ❌ Missing data-scope attribute
div { class: "{css}_container", "Content" }

// ✅ Add data-scope for element scoping
div { 
    "data-scope": "{css}",
    class: "{css}_container", 
    "Content" 
}

Class name doesn't match

// CSS file
.button { color: red; }

// ❌ Wrong class name
button { class: "{css}_btn" }

// ✅ Match the class name exactly
button { class: "{css}_button" }

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. See CONTRIBUTING.md for guidelines.

License

This project is licensed under either of:

at your option.

Credits

Built for the Dioxus framework.

Changelog

See CHANGELOG.md for detailed version history.

Made with ❤️ for the Dioxus community