Enhance documentation and configuration for static site generator

- Update README for clarity and quick start instructions
- Refine default config.toml with hostname and base path
- Adjust index.md files for consistent heading levels
- Simplify CSS for code block styling and remove unnecessary theme switching
- Refactor SiteConfig to derive full base URL from hostname and base path
- Update MarkdownRenderer to remove light theme handling

docs-gen/src/builder.rs

@@ -55,7 +55,7 @@ struct Page {
 
 pub fn build(src: &Path, out: &Path) -> Result<()> {
     let config = SiteConfig::load(src)?;
-    let renderer = MarkdownRenderer::new(config.highlight_theme(), config.highlight_theme_light());
+    let renderer = MarkdownRenderer::new(config.highlight_theme());
 
     // Build Tera: start with embedded defaults, then override with user templates
     let tera = build_tera(src)?;
@@ -125,7 +125,7 @@ pub fn build(src: &Path, out: &Path) -> Result<()> {
             ctx.insert("site", &SiteContext {
                 title: config.site.title.clone(),
                 version: config.site.version.clone(),
-                base_url: config.site.base_url.clone(),
+                base_url: config.site.base_url(),
                 base_path: config.site.base_path.clone(),
                 langs: config.i18n.langs.clone(),
                 nav: config.nav.clone(),
@@ -351,7 +351,7 @@ fn generate_root_redirect(out: &Path, config: &SiteConfig) -> Result<()> {
 <p>Redirecting to <a href="{base_path}/{default_lang}/">{base_path}/{default_lang}/</a>...</p>
 </body>
 </html>"#,
-        default_lang = config.i18n.default_lang,
+        default_lang = config.i18n.default_lang(),
         base_path = base_path,
     );
 

docs-gen/src/config.rs

@@ -27,21 +27,39 @@ pub struct NavLink {
 pub struct Site {
     pub title: String,
     pub version: Option<String>,
-    pub base_url: String,
+    /// Optional hostname (e.g. "https://example.github.io"). Combined with
+    /// base_path to form the full base URL.
+    pub hostname: Option<String>,
     #[serde(default)]
     pub base_path: String,
 }
 
+impl Site {
+    /// Returns the full base URL derived from hostname + base_path.
+    /// Falls back to base_path alone if hostname is not set.
+    pub fn base_url(&self) -> String {
+        match &self.hostname {
+            Some(h) => format!("{}{}", h.trim_end_matches('/'), self.base_path),
+            None => self.base_path.clone(),
+        }
+    }
+}
+
 #[derive(Debug, Deserialize)]
 pub struct I18n {
-    pub default_lang: String,
     pub langs: Vec<String>,
 }
 
+impl I18n {
+    /// Returns the default language, which is the first entry in langs.
+    pub fn default_lang(&self) -> &str {
+        self.langs.first().map(|s| s.as_str()).unwrap_or("en")
+    }
+}
+
 #[derive(Debug, Deserialize)]
 pub struct Highlight {
     pub theme: Option<String>,
-    pub theme_light: Option<String>,
 }
 
 impl SiteConfig {
@@ -51,6 +69,12 @@ impl SiteConfig {
             std::fs::read_to_string(&path).with_context(|| format!("Failed to read {}", path.display()))?;
         let mut config: SiteConfig =
             toml::from_str(&content).with_context(|| format!("Failed to parse {}", path.display()))?;
+
+        // Validate required fields
+        if config.i18n.langs.is_empty() {
+            anyhow::bail!("[i18n] langs must not be empty. Please specify at least one language.");
+        }
+
         // Normalize base_path: strip trailing slash (but keep empty for root)
         let bp = config.site.base_path.trim_end_matches('/').to_string();
         config.site.base_path = bp;
@@ -63,10 +87,4 @@ impl SiteConfig {
             .and_then(|h| h.theme.as_deref())
             .unwrap_or("base16-ocean.dark")
     }
-
-    pub fn highlight_theme_light(&self) -> Option<&str> {
-        self.highlight
-            .as_ref()
-            .and_then(|h| h.theme_light.as_deref())
-    }
 }

docs-gen/src/markdown.rs

@@ -17,16 +17,14 @@ pub struct MarkdownRenderer {
     syntax_set: SyntaxSet,
     theme_set: ThemeSet,
     theme_name: String,
-    theme_light_name: Option<String>,
 }
 
 impl MarkdownRenderer {
-    pub fn new(theme_name: &str, theme_light_name: Option<&str>) -> Self {
+    pub fn new(theme_name: &str) -> Self {
         Self {
             syntax_set: SyntaxSet::load_defaults_newlines(),
             theme_set: ThemeSet::load_defaults(),
             theme_name: theme_name.to_string(),
-            theme_light_name: theme_light_name.map(|s| s.to_string()),
         }
     }
 
@@ -95,17 +93,7 @@ impl MarkdownRenderer {
             .find_syntax_by_token(lang)
             .unwrap_or_else(|| self.syntax_set.find_syntax_plain_text());
 
-        let dark_html = self.highlight_with_theme(code, syntax, &self.theme_name);
-
-        if let Some(ref light_name) = self.theme_light_name {
-            let light_html = self.highlight_with_theme(code, syntax, light_name);
-            format!(
-                "<div class=\"code-dark\">{}</div><div class=\"code-light\">{}</div>",
-                dark_html, light_html
-            )
-        } else {
-            dark_html
-        }
+        self.highlight_with_theme(code, syntax, &self.theme_name)
     }
 
     fn highlight_with_theme(