code: func (t *tree) parseCss(token item) ast.Node {
  	var cmdText = t.expect(itemText, "css")
  	t.expect(itemRightDelim, "css")
  	var lastComma = strings.LastIndex(cmdText.val, ",")
  	if lastComma == -1 {
  		return &ast.CssNode{token.pos, nil, strings.TrimSpace(cmdText.val)}
  	}
  	var exprText = strings.TrimSpace(cmdText.val[:lastComma])
  	return &ast.CssNode{
  		token.pos,
  		t.parseQuotedExpr(exprText),
  		strings.TrimSpace(cmdText.val[lastComma+1:]),
  	}
  }
docs: // "css" has just been read.