css-inline

css-inline inlines CSS into HTML documents, using components from Mozilla's Servo project.

This process is essential for sending HTML emails as you need to use "style" attributes instead of "style" tags.

For instance, the crate transforms HTML like this:

html <html> <head> <title>Test</title> <style>h1 { color:blue; }</style> </head> <body> <h1>Big Text</h1> </body> </html>

into:

html <html> <head> <title>Test</title> </head> <body> <h1 style="color:blue;">Big Text</h1> </body> </html>

Uses reliable components from Mozilla's Servo
Inlines CSS from style and link tags
Removes style and link tags
Resolves external stylesheets (including local files)
Works on Linux, Windows, and macOS
Supports HTML5 & CSS3

Installation

To include it in your project, add the following line to the dependencies section in your project's Cargo.toml file:

toml [dependencies] css-inline = "0.10"

The Minimum Supported Rust Version is 1.60.

Usage

```rust const HTML: &str = r#" Test

Big Text

"#;

fn main() -> Result<(), cssinline::InlineError> { let inlined = cssinline::inline(HTML)?; // Do something with inlined HTML, e.g. send an email Ok(()) } ```

Configuration

css-inline can be configured by using CSSInliner::options() that implements the Builder pattern:

```rust const HTML: &str = "...";

fn main() -> Result<(), cssinline::InlineError> { let inliner = cssinline::CSSInliner::options() .loadremotestylesheets(false) .build(); let inlined = inliner.inline(HTML); // Do something with inlined HTML, e.g. send an email Ok(()) } ```

keep_style_tags. Specifies whether to keep "style" tags after inlining. Default: false
keep_link_tags. Specifies whether to keep "link" tags after inlining. Default: false
base_url. The base URL used to resolve relative URLs. If you'd like to load stylesheets from your filesystem, use the file:// scheme. Default: None
load_remote_stylesheets. Specifies whether remote stylesheets should be loaded. Default: true
extra_css. Extra CSS to be inlined. Default: None
preallocate_node_capacity. Advanced. Preallocates capacity for HTML nodes during parsing. This can improve performance when you have an estimate of the number of nodes in your HTML document. Default: 32

You can also skip CSS inlining for an HTML tag by adding the data-css-inline="ignore" attribute to it:

html <head> <title>Test</title> <style>h1 { color:blue; }</style> </head> <body>  <h1 data-css-inline="ignore">Big Text</h1> </body>

The data-css-inline="ignore" attribute also allows you to skip link and style tags:

html <head> <title>Test</title>  <style data-css-inline="ignore">h1 { color:blue; }</style> </head> <body> <h1>Big Text</h1> </body>

If you'd like to load stylesheets from your filesystem, use the file:// scheme:

```rust const HTML: &str = "...";

fn main() -> Result<(), cssinline::InlineError> { let baseurl = cssinline::Url::parse("file://styles/email/").expect("Invalid URL"); let inliner = cssinline::CSSInliner::options() .baseurl(Some(baseurl)) .build(); let inlined = inliner.inline(HTML); // Do something with inlined HTML, e.g. send an email Ok(()) } ```

Standards support & restrictions

css-inline is built on top of html5ever and cssparser and relies on their behavior for HTML & CSS parsing.

Only HTML 5 is supported, not XHTML.
Only CSS 3 is supported.
Only UTF-8 encoding for string representation. Other document encodings are not yet supported.

Bindings

We provide bindings for Python and WebAssembly. Check the bindings directory for more information.

Command Line Interface

Installation

Install with cargo:

text cargo install css-inline

Usage

The following command inlines CSS in multiple documents in parallel. Resulting files will be saved as inlined.email1.html and inlined.email2.html:

text css-inline email1.html email2.html

For full details of the options available, you can use the --help flag:

text css-inline --help

Extra materials

If you're interested in learning how this library was created and how it works internally, check out these articles:

Support

If you have any questions or discussions related to this library, please join our gitter!

License

This project is licensed under the terms of the MIT license.