fix(layout): resolve the real cascade; add a UA stylesheet and border-style

AGENTS.md

@@ -33,8 +33,8 @@ reasoned allow only when the lint is a genuine false positive.
   single `browser_oxide` crate (`crates/browser_oxide`), organized into
   modules — `dom`, `html_parser`, `js_runtime`, `event_loop`, `net`,
   `stealth`, `canvas`, `workers`, `css_parser`/`css_selectors`/
-  `css_values`/`css_cascade`, `layout`, `protocol`, `host` — each with a
-  single responsibility (see `docs/ARCHITECTURE.md`). The workspace
+  `css_values`/`css_cascade`, `style`, `layout`, `render`, `protocol`, `host` —
+  each with a single responsibility (see `docs/ARCHITECTURE.md`). The workspace
   publishes exactly two crates: `browser_oxide` and the `browser_oxide_mcp`
   server. `browser_oxide_py` is a standalone (PyPI) workspace.
 - **Per-vendor challenge solving is out of scope here.** The engine

crates/browser_oxide/Cargo.toml

@@ -88,6 +88,12 @@
 ] }
 fontdb = { version = "0.23", default-features = false }
 rustybuzz = "0.20"
+# Inline layout. All MIT OR Apache-2.0, so deny.toml needs no exception.
+unicode-bidi = "0.3"
+unicode-linebreak = "0.1"
+unicode-segmentation = "1"
+unicode-script = "0.5"
+ttf-parser = "0.25"
 swash = "0.2"
 rustfft = "6"
 glow = { version = "0.18", optional = true }

crates/browser_oxide/examples/screenshot.rs

@@ -0,0 +1,47 @@
+//! Render a page to a PNG.
+//!
+//! ```text
+//! cargo run --release -p browser_oxide --example screenshot -- https://example.com out.png
+//! cargo run --release -p browser_oxide --example screenshot -- page.html out.png
+//! ```
+//!
+//! The engine could not do this at all until the `render` module existed: Skia
+//! was a dependency used only by `<canvas>`, and the CDP surface implemented 48
+//! methods of which `Page.captureScreenshot` was not one.
+
+use browser_oxide::Page;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let mut args = std::env::args().skip(1);
+    let target = args.next().unwrap_or_else(|| {
+        eprintln!("usage: screenshot <url|file.html> [out.png] [width] [height]");
+        std::process::exit(2);
+    });
+    let out = args.next().unwrap_or_else(|| "screenshot.png".to_string());
+    let width: u32 = args.next().and_then(|s| s.parse().ok()).unwrap_or(1280);
+    let height: u32 = args.next().and_then(|s| s.parse().ok()).unwrap_or(800);
+
+    let mut page = if target.starts_with("http://") || target.starts_with("https://") {
+        let profile = browser_oxide::stealth::presets::chrome_148_linux();
+        let client = browser_oxide::net::HttpClient::new(&profile)?;
+        Page::navigate_simple(&target, &client, profile).await?
+    } else {
+        let html = std::fs::read_to_string(&target)?;
+        Page::from_html(&html, None).await?
+    };
+
+    let started = std::time::Instant::now();
+    let png = page
+        .screenshot_png(width, height)
+        .ok_or("nothing to capture: the page has no document")?;
+    let elapsed = started.elapsed();
+
+    std::fs::write(&out, &png)?;
+    println!(
+        "wrote {out} — {width}x{height}, {} KiB, {:.1} ms",
+        png.len() / 1024,
+        elapsed.as_secs_f64() * 1000.0
+    );
+    Ok(())
+}

crates/browser_oxide/src/css_cascade/computed.rs

@@ -113,6 +113,14 @@ fn all_property_ids() -> Vec<PropertyId> {
         PropertyId::BorderRightWidth,
         PropertyId::BorderBottomWidth,
         PropertyId::BorderLeftWidth,
+        PropertyId::BorderTopStyle,
+        PropertyId::BorderRightStyle,
+        PropertyId::BorderBottomStyle,
+        PropertyId::BorderLeftStyle,
+        PropertyId::BorderTopColor,
+        PropertyId::BorderRightColor,
+        PropertyId::BorderBottomColor,
+        PropertyId::BorderLeftColor,
         PropertyId::BoxSizing,
         PropertyId::OverflowX,
         PropertyId::OverflowY,

crates/browser_oxide/src/css_cascade/initial.rs

@@ -30,6 +30,25 @@ pub fn initial_value(property: &PropertyId) -> CssValue {
         | PropertyId::PaddingLeft => {
             CssValue::LengthPercentage(LengthPercentage::Length(Length::Zero))
         }
+        PropertyId::BorderTopStyle
+        | PropertyId::BorderRightStyle
+        | PropertyId::BorderBottomStyle
+        | PropertyId::BorderLeftStyle => {
+            CssValue::BorderStyle(crate::css_values::types::display::BorderStyle::None)
+        }
+        // `currentColor`. The engine has no keyword for it, so the initial is
+        // the initial `color` — correct for the overwhelmingly common case
+        // where `color` is not set on the element itself, and closer than
+        // transparent for the rest.
+        PropertyId::BorderTopColor
+        | PropertyId::BorderRightColor
+        | PropertyId::BorderBottomColor
+        | PropertyId::BorderLeftColor => CssValue::Color(Color::Rgba {
+            r: 0,
+            g: 0,
+            b: 0,
+            a: 1.0,
+        }),
         PropertyId::BorderTopWidth
         | PropertyId::BorderRightWidth
         | PropertyId::BorderBottomWidth