type color = int * int * inttype align = | Left| Center| Right
type t = {size : float;bold : bool;italic : bool;underline : bool;strike : bool;monospace : bool;color : color;link : string option;pre : bool;align : align;link_color : color;visited_color : color;base : float;extensions : bool;
}val root : ?extensions:bool -> size:float -> unit -> tval color_of_string : string -> color optionval font_scale : string -> float optiontype display = | Block| Inline| Rule| Hidden
type box = {display : display;margin_top : float;margin_bottom : float;indent : float;right : float;background : color option;
}val styled : parent:t -> t -> (string * string) list -> tval styled_box : t -> box -> (string * string) list -> boxval length : em:float -> ?percent:float -> string -> float option