diff --git a/README.md b/README.md
index e69de29..fdb4ea4 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,63 @@
+# YAMD
+
+Indentation-based markup language that compiles to HTML via Ruby codegen.
+
+## Syntax
+
+Structure is defined by indentation (tabs). Lines at a given indent level belong to the enclosing directive.
+
+### Directives (line-start only)
+
+| Syntax | Description |
+|--------|-------------|
+| `#% <ruby code>` | Metadata / Ruby statement. e.g. `#% meta "date", "2025 01 01"` |
+| `#! <expr>` | Block wrapper. Evaluates `expr` as a Ruby method call, content is passed as a block. e.g. `#! tag('h1')` |
+| `#$ <expr>` | Raw block. Like `#!` but inner lines are passed as a raw string (no YAMD parsing). Used for code blocks. e.g. `#$ code` |
+| `#. ` | List item. Must appear inside a `#! list(...)` block |
+
+### Inline constructs
+
+| Syntax | Description |
+|--------|-------------|
+| `` #`...` `` | Inline code |
+| `#{expr}` | Ruby expression interpolation (result converted to string) |
+| `#(expr)` | Inline math (AsciiMath, rendered to MathML) |
+| `#name(args)` | Method call. e.g. `#link("url")` |
+| `#name(args)#{ content }#` | Method call with content block. e.g. `#link("url")#{ click here }#` |
+| `##` | Escaped literal `#` |
+| `}#` | Closes a `#{` content block |
+
+### Comments
+
+Lines matching `#` followed by nothing or a space (i.e. `#` or `# ...`) are comments and are skipped.
+
+### Available renderer methods
+
+These are defined by `HTMLRenderer` in `exe/yamd`:
+
+| Method | Usage |
+|--------|-------|
+| `tag(name, **attrs)` | HTML element. `#! tag('h2')` |
+| `list(numbering)` | List. numbering: `"-"` (ul), `"1"`, `"a"`, `"A"`, `"i"`, `"I"` (ol). Dot-separated for nested: `"-.1"` |
+| `link(url)` | Anchor tag. `#link("https://example.com")#{ text }#` |
+| `code(lang: Lang::DEFAULT)` | Code block (used via `#$`). Optional `lang:` for highlighting rules |
+| `meta(name, value)` | HTML `<meta>` tag. Used via `#%` |
+| `inline_code(text)` | Inline `<code>`. Used via `` #`...` `` |
+| `inline_math(text)` | AsciiMath to MathML. Used via `#(...)` |
+
+### Example
+
+```
+#% meta "date", "2025 01 01"
+
+#! tag('h1')
+	Title
+
+Paragraph text with #`inline code` and #link("https://example.com")#{ a link }#.
+
+#! list('-')
+	#. First item
+	#. Second item with sub-content
+		#$ code
+			x = 1
+```
diff --git a/exe/yamd b/exe/yamd
index f43a35a..e160705 100755
--- a/exe/yamd
+++ b/exe/yamd
@@ -91,6 +91,23 @@ class HTMLRenderer < YAMD::Renderer
 		}
 	end
 
+	def single_tag(name, **attrs)
+		@buf << "<#{name}"
+		attrs.each { |k, v|
+			@buf << " "
+			if k.kind_of? Symbol
+				k = k.to_s
+			end
+			@buf << k
+			@buf << "=" << v.dump
+		}
+		@buf << "/>"
+	end
+
+	def meta(name, value)
+		single_tag('meta', name: name, content: value)
+	end
+
 	def tag(name, **attrs)
 		@buf << "<#{name}"
 		attrs.each { |k, v|
@@ -110,16 +127,16 @@ class HTMLRenderer < YAMD::Renderer
 		tag('a', href: to, &blk)
 	end
 
-	def code(&blk)
+	def code(lang: YAMD::Code::Lang::DEFAULT, &blk)
 		tag('pre', class: "language-any") {
 			tag('code', class: "language-any") {
-				@buf << YAMD::Code::highlight(blk.())
+				@buf << YAMD::Code::highlight(blk.(), lang)
 			}
 		}
 	end
 
 	def inline_code(text)
-		tag('code') {
+		tag('code', class: "code-inline") {
 			@buf << YAMD::Code::highlight(text)
 		}
 	end
diff --git a/lib/yamd/code.rb b/lib/yamd/code.rb
index 73e666e..ea7854f 100644
--- a/lib/yamd/code.rb
+++ b/lib/yamd/code.rb
@@ -21,7 +21,7 @@ module YAMD::Code
 		DEFAULT = {
 			/\b(?:[A-Z][a-zA-Z\-_0-9]*)\b*/ => 'type',
 			/#(\s|$)[^\n]*/ => 'comment',
-			/\b(?:open|final|class|fn|let|var|if|else|while|loop|return|namespace|new)\b/ => 'kw',
+			/\b(?:open|final|class|struct|enum|fn|let|var|if|else|while|loop|return|namespace|new)\b/ => 'kw',
 			/\b(?:def|import|from)\b/ => 'kw',
 			/\b(?:null|undefined|true|false|this|self)\b/i => 'const',
 			/\b(?:__[a-zA-Z0-9_]+__)\b/i => 'const',
@@ -30,6 +30,19 @@ module YAMD::Code
 			/"(?:\\.|[^\\"])*"/ => 'str',
 			/'(?:\\.|[^\\'])*'/ => 'str',
 		}
+
+		GD_SCRIPT = {
+			/\b(?:[A-Z_]+[A-Z_0-9]*)\b/ => 'const',
+			/\b(?:[A-Z][a-zA-Z\-_0-9]*)\b*/ => 'type',
+			/#(\s|$)[^\n]*/ => 'comment',
+			/\b(?:class|struct|enum|var|func|const|if|else|while|return)\b/ => 'kw',
+			/\b(?:class_name|extends)\b/ => 'kw',
+			/\b(?:null|true|false|self)\b/i => 'const',
+			/[:,;()\[\]{}<>]/ => 'punct',
+			/0|(0x[0-9a-fA-F]+)|([1-9][0-9]*(\.[0-9]+)?)/ => 'number',
+			/"(?:\\.|[^\\"])*"/ => 'str',
+			/'(?:\\.|[^\\'])*'/ => 'str',
+		}
 	end
 
 	def self.highlight(txt, highlights=Lang::DEFAULT)