Ships the default HTML stylesheet as a linked asset, not inline

crates/core/src/assets/mod.rs

@@ -193,6 +193,42 @@ impl<'a> AssetResolver<'a> {
                         paths.join(", ")
                     )));
                 }
+                // No on-disk source: fall back to the plugin's embedded default
+                // (if any), written as a real file so it is copied + linked like
+                // any other asset instead of being inlined.
+                if let Some(embedded) = asset_config.default_content {
+                    let rel = embedded.name.to_string();
+                    if let Some(prev) = seen_relative_paths.get(&rel) {
+                        return Err(RheoError::project_config(format!(
+                            "asset path collision: output '{}' would be written by both '{}' and the embedded default for '{}'",
+                            rel,
+                            prev.display(),
+                            asset_config.name
+                        )));
+                    }
+                    let dest = self.plugin_output_dir.join(&rel);
+                    if let Some(parent) = dest.parent() {
+                        std::fs::create_dir_all(parent).map_err(|e| {
+                            RheoError::io(
+                                e,
+                                format!("creating directory for embedded default '{}'", rel),
+                            )
+                        })?;
+                    }
+                    std::fs::write(&dest, embedded.content).map_err(|e| {
+                        RheoError::io(e, format!("writing embedded default asset to {:?}", dest))
+                    })?;
+                    seen_relative_paths.insert(rel.clone(), dest.clone());
+                    resolved.insert(
+                        asset_config.name,
+                        vec![Asset {
+                            config: asset_config.clone(),
+                            source_path: dest.clone(),
+                            resolved_path: dest.clone(),
+                            built_relative_path: rel,
+                        }],
+                    );
+                }
                 continue;
             }
 
@@ -360,6 +396,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -387,6 +424,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let mut asset_extra = toml::map::Map::new();
@@ -423,6 +461,7 @@ mod tests {
                 name: "missing_asset",
                 default_path: "nonexistent.css",
                 required: true,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -450,6 +489,7 @@ mod tests {
                 name: "optional_asset",
                 default_path: "nonexistent.css",
                 required: false,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -479,6 +519,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let mut asset_extra = toml::map::Map::new();
@@ -522,6 +563,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -570,6 +612,7 @@ mod tests {
                 name: "missing_asset",
                 default_path: "nonexistent.css",
                 required: true,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -599,6 +642,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: true,
+                default_content: None,
             }],
         };
 
@@ -652,6 +696,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -714,6 +759,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -758,6 +804,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -799,6 +846,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -851,6 +899,7 @@ mod tests {
                 name: "js_scripts",
                 default_path: "script.js",
                 required: false,
+                default_content: None,
             }],
         };
 
@@ -897,6 +946,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -939,6 +989,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let section = PluginSection::default();
@@ -984,6 +1035,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         let mut user_extra = toml::map::Map::new();
@@ -1035,6 +1087,7 @@ mod tests {
                 name: "css_stylesheet",
                 default_path: "style.css",
                 required: false,
+                default_content: None,
             }],
         };
         // User declares custom.css for dest "pkg"

crates/core/src/build.rs

@@ -320,16 +320,22 @@ impl Build {
         // Inject CSS/JS link tags into each HTML entry in memory.
         let needs_injection = !css_paths.is_empty() || !js_paths.is_empty();
         if needs_injection {
-            let css_refs: Vec<&str> = css_paths.iter().map(|s| s.as_str()).collect();
-            let js_refs: Vec<&str> = js_paths.iter().map(|s| s.as_str()).collect();
             let injected: Result<typst_bundle::VirtualFs> = virtual_fs
                 .into_iter()
                 .map(|(vpath, bytes)| {
                     let path_str = vpath.get_with_slash().trim_start_matches('/').to_string();
                     if path_str.ends_with(".html") {
                         let html = String::from_utf8_lossy(&bytes);
                         let mut dom = crate::util::html::HtmlDom::parse(&html)?;
-                        dom.inject_head_links(&[], &css_refs, &js_refs)?;
+                        // Depth-relative asset refs so nested pages resolve them.
+                        let prefix = crate::util::html::depth_prefix(&path_str);
+                        let css_refs: Vec<String> =
+                            css_paths.iter().map(|s| format!("{prefix}{s}")).collect();
+                        let js_refs: Vec<String> =
+                            js_paths.iter().map(|s| format!("{prefix}{s}")).collect();
+                        let css: Vec<&str> = css_refs.iter().map(|s| s.as_str()).collect();
+                        let js: Vec<&str> = js_refs.iter().map(|s| s.as_str()).collect();
+                        dom.inject_head_links(&[], &css, &js)?;
                         let modified = dom.serialize()?;
                         Ok((vpath, typst::foundations::Bytes::new(modified.into_bytes())))
                     } else {

crates/core/src/lib.rs

@@ -34,8 +34,8 @@ pub use config::{AssetsField, PluginAssets, PluginSection, Spine};
 // Plugin trait and context
 pub use parser::RheoValue;
 pub use plugins::{
-    AssetConfig, CastVertebra, FormatInitTemplate, FormatPlugin, OpenHandle, PackageAssets,
-    PluginContext, ResolvedPackage, ServerHandle, SpineLayoutKind, TypstFormat,
+    AssetConfig, CastVertebra, EmbeddedDefault, FormatInitTemplate, FormatPlugin, OpenHandle,
+    PackageAssets, PluginContext, ResolvedPackage, ServerHandle, SpineLayoutKind, TypstFormat,
 };
 
 // HTML/PDF export utilities

crates/core/src/plugins/mod.rs

@@ -33,6 +33,18 @@ pub enum OpenHandle {
 
 use crate::config::PluginAssets;
 
+/// An embedded fallback for an asset: content the plugin ships built in, written
+/// into the output directory (under `name`) when no on-disk source resolves, then
+/// linked like any copied asset. Lets a plugin ship a default (e.g. the HTML
+/// default stylesheet) as a real linked file rather than inlining it.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct EmbeddedDefault {
+    /// Output filename (relative to the plugin output dir) to write the content as.
+    pub name: &'static str,
+    /// The verbatim bytes to write.
+    pub content: &'static str,
+}
+
 /// Declares an additional non-Typst input file needed from the project directory.
 #[derive(Debug, Clone)]
 pub struct AssetConfig {
@@ -43,6 +55,9 @@ pub struct AssetConfig {
     pub default_path: &'static str,
     /// If true, a missing file is a compile error; if false, it is absent from ctx.inputs
     pub required: bool,
+    /// Embedded fallback written to the output dir and linked when no on-disk
+    /// source (default path or override) resolves. `None` = no fallback.
+    pub default_content: Option<EmbeddedDefault>,
 }
 
 #[derive(Debug, Clone)]