diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ba7ce2a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+_build
+*~
+*#
+
diff --git a/app/dune b/app/dune
index 21dd2eb..2fe3b23 100644
--- a/app/dune
+++ b/app/dune
@@ -1,3 +1,4 @@
 (executable
  (name main)
- (libraries cmdliner logs logs.fmt opam-graph))
\ No newline at end of file
+ (public_name opam_graph)
+ (libraries cmdliner logs logs.fmt fmt.cli fmt.tty logs.cli opam-graph))
diff --git a/app/main.ml b/app/main.ml
index 425b9aa..dfc0c83 100644
--- a/app/main.ml
+++ b/app/main.ml
@@ -11,13 +11,58 @@ let read_file file =
       invalid_arg ("Error reading file: " ^ file)
   with _ -> invalid_arg ("Error opening file " ^ file)
 
-let () =
-  match Sys.argv with
-  | [| _ ; file |] ->
-    let switch = read_file file in
-    let data = OpamFile.SwitchExport.read_from_string switch in
-    Opam_graph.dependencies data
-  | _ ->
-    print_endline "expecting exactly one argument";
-    exit 1
+let jump () transitive file output_format =
+  let switch = read_file file in
+  let data = OpamFile.SwitchExport.read_from_string switch in
+  match output_format with
+  | `Text ->
+    let graph = Opam_graph.dependencies ~transitive data in
+    Format.printf "%a" Opam_graph.pp_graph graph
+  | `Dot ->
+    let graph = Opam_graph.dependencies ~transitive data in
+    let dot = Opam_graph.Render.Dot.of_graph graph in
+    Format.printf "%a" Opam_graph.Render.Dot.pp dot
+  | `Dot_ui ->
+    let graph = Opam_graph.Ui.dependencies ~transitive data in
+    let dot = Opam_graph.Render.Dot.of_assoc graph in
+    Format.printf "%a" Opam_graph.Render.Dot.pp dot
+  | `Html ->
+    let graph = Opam_graph.Ui.dependencies ~transitive data in
+    let html = Opam_graph.Render.Html.of_assoc graph in
+    Format.printf "%a" Opam_graph.Render.Html.pp html
 
+let setup_log style_renderer level =
+  Fmt_tty.setup_std_outputs ?style_renderer ();
+  Logs.set_level level;
+  Logs.set_reporter (Logs_fmt.reporter ~dst:Format.std_formatter ())
+
+open Cmdliner
+
+let setup_log =
+  Term.(const setup_log
+        $ Fmt_cli.style_renderer ()
+        $ Logs_cli.level ())
+
+let transitive =
+  let doc = "Transitive dependencies" in
+  Arg.(value & flag & info [ "transitive" ] ~doc)
+
+let formats = [ "html", `Html ; "dot", `Dot ; "dot-ui", `Dot_ui ; "text", `Text ]
+
+let output_format =
+  let doc =
+    let formats_str =
+      formats |> List.map fst |> String.concat ", "
+    in
+    Printf.sprintf "Output format. Can be one of: %s." formats_str in
+  Arg.(value & opt (Arg.enum formats) `Text & info [ "output-format" ] ~doc)
+
+let file =
+  let doc = "The opam switch export to graph" in
+  Arg.(required & pos 0 (some file) None & info [ ] ~doc ~docv:"FILE")
+
+let cmd =
+  Term.(const jump $ setup_log $ transitive $ file $ output_format),
+  Term.info "opam_graph" ~version:"%%VERSION%%"
+
+let () = match Term.eval cmd with `Ok () -> exit 0 | _ -> exit 1
diff --git a/opam-graph.opam b/opam-graph.opam
index e69de29..8ab3aa8 100644
--- a/opam-graph.opam
+++ b/opam-graph.opam
@@ -0,0 +1,30 @@
+opam-version: "2.0"
+maintainer: "Robur <team@robur.coop>"
+authors: ["Robur <team@robur.coop>"]
+homepage: "https://git.robur.io/robur/opam-graph"
+dev-repo: "git+https://git.robur.io/robur/opam-graph.git"
+bug-reports: "https://github.com/roburio/opam-graph/issues"
+license: "ISC"
+
+depends: [
+  "ocaml" {>= "4.08.0"}
+  "dune" {>= "2.0.0"}
+  "cmdliner"
+  "fmt" {>= "0.8.7"}
+  "logs"
+  "opam-core"
+  "opam-format"
+  "ocamldot"
+  "rresult"
+  "tyxml"
+  "gg"
+]
+build: [
+  ["dune" "subst"] {dev}
+  ["dune" "build" "-p" name "-j" jobs]
+]
+
+synopsis: "Graphing dependencies of opam packages"
+description: """
+This package outputs graphs (in svg and dot) of opam packages.
+"""
diff --git a/src/dune b/src/dune
index 0f484b0..54bb00c 100644
--- a/src/dune
+++ b/src/dune
@@ -1,4 +1,5 @@
 (library
  (name opam_graph)
  (public_name opam-graph)
- (libraries opam-core opam-format))
\ No newline at end of file
+ (libraries opam-core opam-format dot rresult tyxml gg)
+ )
diff --git a/src/opam_graph.ml b/src/opam_graph.ml
index 471de3e..c83e230 100644
--- a/src/opam_graph.ml
+++ b/src/opam_graph.ml
@@ -1,16 +1,19 @@
-module Set = OpamPackage.Set
+
+let sprintf = Printf.sprintf
+
+module OSet = OpamPackage.Set
 
 type package = OpamPackage.t
 
 let packages (switch : OpamFile.SwitchExport.t) =
-  assert (Set.cardinal switch.selections.sel_pinned = 0);
-  assert (Set.cardinal switch.selections.sel_compiler = 0);
-  assert (Set.subset switch.selections.sel_roots switch.selections.sel_installed);
+  assert (OSet.cardinal switch.selections.sel_pinned = 0);
+  assert (OSet.cardinal switch.selections.sel_compiler = 0);
+  assert (OSet.subset switch.selections.sel_roots switch.selections.sel_installed);
   switch.selections.sel_installed
 
 let root (switch : OpamFile.SwitchExport.t) =
-  assert (Set.cardinal switch.selections.sel_roots = 1);
-  Set.choose switch.selections.sel_roots
+  assert (OSet.cardinal switch.selections.sel_roots = 1);
+  OSet.choose switch.selections.sel_roots
 
 module Name_set = OpamPackage.Name.Set
 
@@ -18,16 +21,43 @@ let filtered_formula_to_pkgs (_switch : OpamFile.SwitchExport.t)
     ?(set = Name_set.empty) formula =
   OpamFormula.fold_left (fun acc (name, _) -> Name_set.add name acc) set formula
 
-let opam (switch : OpamFile.SwitchExport.t) pkg_name =
+let opam_file (switch : OpamFile.SwitchExport.t) pkg_name =
   OpamPackage.Name.Map.find pkg_name switch.overlays
 
 (* TODO depexts *)
 (* TODO build / dev packages *)
 (* TODO constraints (os = "linux") *)
 let direct_dependencies (switch : OpamFile.SwitchExport.t) pkg =
-  let opam = opam switch pkg in
-  let set = filtered_formula_to_pkgs switch (OpamFile.OPAM.depends opam) in
-  filtered_formula_to_pkgs switch ~set (OpamFile.OPAM.depopts opam)
+  let pkg_opam_file = opam_file switch pkg in
+  let set = filtered_formula_to_pkgs switch (OpamFile.OPAM.depends pkg_opam_file) in
+  filtered_formula_to_pkgs switch ~set (OpamFile.OPAM.depopts pkg_opam_file)
+
+let transitive_dependencies (switch : OpamFile.SwitchExport.t) pkg =
+  let available = switch.selections.sel_installed in
+  let rec aux pkg seen_pkgs =
+    let opam = opam_file switch pkg in
+    let set = filtered_formula_to_pkgs switch (OpamFile.OPAM.depends opam) in
+    let set = filtered_formula_to_pkgs switch ~set (OpamFile.OPAM.depopts opam) in
+    let transitive_set =
+      let filtered_set =
+        set
+        |> Name_set.filter (fun name ->
+          OpamPackage.Set.exists
+            (fun pkg -> pkg.OpamPackage.name = name)
+            available
+          && not (Name_set.mem name seen_pkgs)
+        )
+      in
+      let seen_pkgs = Name_set.union seen_pkgs filtered_set
+      in
+      filtered_set
+      |> Name_set.elements
+      |> List.concat_map (fun pkg -> aux pkg seen_pkgs |> Name_set.elements)
+      |> Name_set.of_list
+    in
+    Name_set.union set transitive_set
+  in
+  aux pkg Name_set.empty
 
 module Name_map = OpamPackage.Name.Map
 
@@ -49,7 +79,7 @@ let pp_graph ppf graph =
                                (Name_set.elements deps))))
     graph.nodes
 
-let dependencies (switch : OpamFile.SwitchExport.t) =
+let dependencies ?(transitive=false) (switch : OpamFile.SwitchExport.t) =
   let root_pkg = root switch in
   let top = root_pkg.OpamPackage.name in
   let graph = { top ; nodes = Name_map.empty } in
@@ -58,13 +88,17 @@ let dependencies (switch : OpamFile.SwitchExport.t) =
     match Name_set.choose_opt work with
     | None -> graph
     | Some x ->
-      let deps = direct_dependencies switch x in
+      let deps = match transitive with
+        | true -> transitive_dependencies switch x
+        | false -> direct_dependencies switch x
+      in
       let deps =
-        Name_set.filter (fun name ->
-            OpamPackage.Set.exists
-              (fun pkg -> pkg.OpamPackage.name = name)
-              available)
-          deps
+        deps
+        |> Name_set.filter (fun name ->
+          OpamPackage.Set.exists
+            (fun pkg -> pkg.OpamPackage.name = name)
+            available
+        )
       in
       let graph = add_node graph x deps in
       let work =
@@ -74,5 +108,621 @@ let dependencies (switch : OpamFile.SwitchExport.t) =
       in
       find_deps graph work
   in
-  let graph = find_deps graph (Name_set.singleton top) in
-  Format.printf "%a" pp_graph graph
+  find_deps graph (Name_set.singleton top)
+
+(*!Note the first entry is seen as the root node*)
+type assoc_node = {
+  name : string;
+  uniqueness_postfix : string;
+}
+type assoc_graph = (assoc_node * (assoc_node list)) list
+
+module Ui = struct
+
+  let dependencies ?(transitive=true) data : assoc_graph =
+    (*> todo can be made more efficient*)
+    let all_direct_deps = dependencies data in
+    let root = all_direct_deps.top in
+    let root_str = OpamPackage.Name.to_string root
+    in
+    let direct_deps =
+      all_direct_deps.nodes
+      |> Name_map.find root
+    in
+    (*> todo can be made more efficient*)
+    let all_transitive_deps =
+      dependencies ~transitive data in
+    let direct_deps_w_transitive_deps =
+      direct_deps
+      |> Name_set.elements
+      |> List.map (fun direct_dep ->
+        let transitive_deps =
+          all_transitive_deps.nodes
+          |> Name_map.find_opt direct_dep
+          |> (function
+          | None -> Name_set.empty
+          | Some v -> v)
+          |> Name_set.elements
+          |> List.map OpamPackage.Name.to_string
+        in
+        let direct_dep = OpamPackage.Name.to_string direct_dep in
+        direct_dep, transitive_deps
+      )
+    in
+    let uniquified_deps =
+      direct_deps_w_transitive_deps
+      |> List.mapi (fun i (direct_dep, transitive_deps) ->
+        let direct_dep_node = {
+          name = direct_dep;
+          uniqueness_postfix = sprintf "%d" i;
+        }
+        and unique_transitive_deps =
+          transitive_deps
+          |> List.mapi (fun i' transitive_dep ->
+            let uniqueness_postfix = sprintf "%d.%d" i i' in
+            { name = transitive_dep; uniqueness_postfix }
+          )
+        in
+        direct_dep_node, unique_transitive_deps
+      )
+    in
+    let unique_direct_deps = uniquified_deps |> List.map fst in
+    let root_node = { name = root_str; uniqueness_postfix = "" }
+    in
+    (root_node, unique_direct_deps) :: uniquified_deps
+
+end
+
+module Render = struct
+
+  module Dot = struct
+
+    type t = Odot.graph
+
+    let of_graph (graph:graph) : t =
+      let open Odot in
+      let stmt_list =
+        Name_map.fold (fun pkg deps acc ->
+          let stmt =
+            let pkg_id = Double_quoted_id (OpamPackage.Name.to_string pkg) in
+            let pkg_point = Edge_node_id (pkg_id, None) in
+            let deps_points =
+              Name_set.elements deps
+              |> List.map (fun p ->
+                let id = Double_quoted_id (OpamPackage.Name.to_string p) in
+                Edge_node_id (id, None)
+              )
+            in
+            let edge = pkg_point, deps_points, [] in
+            Stmt_edge edge
+          in
+          stmt :: acc
+        ) graph.nodes []
+      in
+      { strict = false; (*todo test params*)
+        kind = Digraph;
+        id = None;
+        stmt_list }
+
+    let id_of_assoc_node node =
+      sprintf "%s_%s" node.name node.uniqueness_postfix
+
+    let of_assoc (graph:assoc_graph) : t =
+      let open Odot in
+      let stmt_list =
+        graph
+        |> List.fold_left (fun acc (pkg, deps) ->
+          let stmt =
+            let pkg_id = Double_quoted_id (id_of_assoc_node pkg) in
+            let pkg_point = Edge_node_id (pkg_id, None) in
+            let deps_points =
+              deps
+              |> List.map (fun pkg ->
+                let id = Double_quoted_id (id_of_assoc_node pkg) in
+                Edge_node_id (id, None)
+              )
+            in
+            let edge = pkg_point, deps_points, [] in
+            Stmt_edge edge
+          in
+          stmt :: acc
+        ) []
+      in
+      { strict = false; (*todo test params*)
+        kind = Digraph;
+        id = None;
+        stmt_list }
+
+    let pp ppf dot =
+      Format.fprintf ppf "%s" (Odot.string_of_graph dot)
+
+  end
+
+  module Svg = struct
+
+    type t = Tyxml_svg.doc
+    type 'a elt = 'a Tyxml_svg.elt
+    type 'a attr = 'a Tyxml_svg.attrib
+
+    type ('a, 'b) output = {
+      svg_content : 'a elt list;
+      svg_attr : 'b attr list;
+      css : string;
+    }
+
+    module Svg = Tyxml_svg
+
+    (*> goto
+      * change svg width+height to pct again - using vw+vh for development
+      * svg width+height shouldn't be here for compatibility with user css?
+    *)
+    let initial_css = {|
+
+svg {
+  background : slategrey;
+}
+
+line {
+  stroke-width: 0.004;
+  stroke: bisque;
+}
+
+.layer2_deps.bg {
+  fill: url(#gradient_01);
+}
+
+.direct_dep.node:hover {
+  transform: scale(2);
+}
+
+.layer2_dep.node:hover {
+  transform: scale(1.4);
+}
+
+|}
+
+    (* disabled CSS
+svg {
+  width : 100vw;
+  height : 100vh;
+}
+
+.layer2_deps.bg {
+  fill: bisque;
+}
+
+.root:hover ~ .node {
+  transform: scale(1.1);
+}
+
+  transform-origin: center;
+  stroke-width: 0.009 !important;
+    *)
+
+    (*< Note the '.layer2_deps.bg' selector...
+      https://steveliles.github.io/a_multi_class_union_css_selector.html*)
+    (* .layer2_deps.bg fills:
+       OCaml: a_fill @@ `Color ("url(#gradient_01)", None);
+       CSS: fill: url(#gradient_01);
+    *)
+
+    let merge_css cs = String.concat "\n" cs
+
+    type position = {
+      x : float;
+      y : float;
+    }
+
+    let center = { x = 0.5; y = 0.5 }
+    let root_radius = 0.015
+
+    module Unit = struct
+
+      let none size = size, None
+
+    end
+
+    let make_title ~text =
+      let s = sprintf "%s" text in
+      Svg.(title (txt s))
+
+    let make_circle ~pos ~radius =
+      Svg.[
+        circle ~a:[
+          a_class ["node_circle"];
+          a_cx @@ Unit.none pos.x;
+          a_cy @@ Unit.none pos.y;
+          a_r @@ Unit.none radius;
+        ] []
+      ]
+
+    let make_square ~center_pos ~width =
+      let open Gg in
+      let center_pos = V2.v center_pos.x center_pos.y in
+      let diagonal = V2.v width width in
+      let center_displacement = V2.half diagonal in
+      let pos = V2.(center_pos - center_displacement) in
+      Svg.[
+        rect ~a:[
+          (* a_stroke @@ `Color ("black", None);
+           * a_stroke_width @@ Unit.none 0.001; *)
+          a_fill @@ `Color ("rgba(0,0,0,0)", None); (*goto control with css*)
+          a_x @@ Unit.none @@ V2.x pos;
+          a_y @@ Unit.none @@ V2.y pos;
+          a_width @@ Unit.none width;
+          a_height @@ Unit.none width;
+        ] []
+      ]
+
+    let make_node ~pos ~radius ~text ~classes =
+      let title = make_title ~text in
+      (*> todo; why is this not in Tyxml - browser support missing?*)
+      let a_transform_origin = Svg.Unsafe.string_attrib "transform-origin" in
+      let a = Svg.[
+        a_class ("node" :: classes);
+        a_transform_origin @@ sprintf "%f %f" pos.x pos.y;
+      ] in
+      Svg.g ~a (title :: make_circle ~pos ~radius)
+
+    let make_line ~pos0 ~pos1 =
+      Svg.(line ~a:[
+        a_x1 @@ Unit.none pos0.x;
+        a_y1 @@ Unit.none pos0.y;
+        a_x2 @@ Unit.none pos1.x;
+        a_y2 @@ Unit.none pos1.y;
+      ]) []
+
+    let make_edge ~pos0 ~pos1 ~text ~classes =
+      let a = [ Svg.a_class ("edge" :: classes) ] in
+      let title = make_title ~text in
+      Svg.g ~a [ title; make_line ~pos0 ~pos1 ]
+
+    let make_direct_dep_text dep ~layer2_deps =
+      sprintf "Direct dependency: %s\nDirect dependencies: %d"
+        dep.name (List.length layer2_deps)
+
+    let make_direct_deps_nodes ~deps_w_positions =
+      deps_w_positions |> List.map (fun ((dep, pos), layer2_deps) ->
+        let radius = root_radius *. 0.7
+        and text = make_direct_dep_text dep ~layer2_deps
+        and classes = [ dep.name; "direct_dep" ] in
+        make_node ~pos ~radius ~text ~classes
+      )
+
+    let make_direct_dep_edge_css dep = sprintf {|
+.direct_dep.edge.%s:hover ~ .direct_dep.node.%s {
+  transform: scale(2);
+}
+.direct_dep.edge.%s:hover ~ .layer2_deps.bg.%s {
+  fill: dimgrey;
+}
+.direct_dep.node.%s:hover ~ .layer2_deps.bg.%s {
+  fill: dimgrey;
+}
+|} dep dep dep dep dep dep
+    (*< goto move generation of node-css to some other place*)
+
+    (*disabled css:
+(*> problem: selected other following children as well*)
+.layer2_dep.hitbox.%s:hover ~ .layer2_dep.node.%s {
+  transform: scale(1.4);
+}
+
+*)
+
+    let make_triangle ~top ~left ~right =
+      let a = Svg.[
+        a_points [
+          top.x, top.y;
+          left.x, left.y;
+          right.x, right.y;
+        ];
+        a_fill @@ `Color ("rgba(0,0,0,0)", None); (*goto control with css*)
+        (* a_stroke @@ `Color ("black", None);
+         * a_stroke_width @@ Unit.none 0.002; *)
+      ] in
+      Svg.polygon ~a []
+
+    let make_hitbox_direct_dep_edge ~pos0 ~pos1 ~n_edges ~text ~classes =
+      let a = [ Svg.a_class ("edge" :: "hitbox" :: classes) ] in
+      let title = make_title ~text in
+      let left, right =
+        let open Gg in
+        let n_edges = float (max 1 n_edges) in
+        let diff_angle = Float.two_pi /. n_edges in
+        let _pos0, pos1 = V2.(v pos0.x pos0.y, v pos1.x pos1.y) in
+        let center = V2.v center.x center.y in
+        let pos1_rel = V2.(pos1 - center) in
+        let height_triangle =
+          let radius_pos1_rel, _ = V2.(to_polar pos1_rel |> to_tuple) in
+          radius_pos1_rel *. 1.2 in
+        let bottom_width =
+          if diff_angle < Float.pi_div_2 then
+            sin diff_angle *. height_triangle (*Note: Scaling sin by ~ circle-radius*)
+          else
+            height_triangle
+        in
+        let normal_pos1 = V2.(ortho pos1_rel / norm pos1_rel) in
+        let normal'_pos1 = V2.(-1. * normal_pos1) in
+        let right_leg = V2.((0.5 *. bottom_width) * normal_pos1) in
+        let left_leg = V2.((0.5 *. bottom_width) * normal'_pos1) in
+        let pos1_unit = V2.(pos1_rel / norm pos1_rel) in
+        let pos1_extended = V2.(height_triangle * pos1_unit + center) in
+        let right = V2.(right_leg + pos1_extended)
+        and left  = V2.(left_leg + pos1_extended) in
+        { x = V2.x left; y = V2.y left },
+        { x = V2.x right; y = V2.y right }
+      in
+      Svg.g ~a [ title; make_triangle ~top:pos0 ~left ~right ]
+
+    let make_direct_deps_edges ~deps_w_positions =
+      let open Gg in
+      let n_edges = deps_w_positions |> List.length in
+      let svg =
+        deps_w_positions |> List.concat_map (fun ((dep, pos), layer2_deps) ->
+          let pos1 = pos in
+          let pos0, _pos0_angle =
+            (*> Note: Need this because of mix of CSS selectors and SVG paint order*)
+            let center = V2.v center.x center.y in
+            let pos1 = V2.v pos1.x pos1.y in
+            let pos1_rel = V2.(pos1 - center) in
+            let pos1_rel_angle = V2.angle pos1_rel in
+            let pos0_rel = V2.(v root_radius pos1_rel_angle |> of_polar) in
+            let pos0 = V2.(pos0_rel + center) in
+            { x = V2.x pos0; y = V2.y pos0 }, pos1_rel_angle
+          in
+          let text = make_direct_dep_text dep ~layer2_deps in
+          let classes = [ dep.name; "direct_dep" ] in
+          let visual_svg = make_edge ~pos0 ~pos1 ~text ~classes in
+          let hitbox_svg =
+            make_hitbox_direct_dep_edge
+              ~pos0 ~pos1 ~n_edges ~text ~classes
+          in
+          [ visual_svg; hitbox_svg ]
+        )
+      in
+      let css =
+        deps_w_positions
+        |> List.fold_left (fun acc_css ((dep, _), _) ->
+          let css = make_direct_dep_edge_css dep.name in
+          merge_css [ acc_css; css ]
+        ) ""
+      in
+      svg, css
+
+    let make_layer2_nodes_spiral ~layer2_deps ~layer2_deps_center =
+      let open Gg in
+      let dot_radius = root_radius *. 0.25 in
+      layer2_deps |> List.mapi (fun i' layer2_dep ->
+        let i' = float i' +. 5.5 in
+        let pos_radius = sqrt i' *. 0.007 -. 0.005 in
+        let angle_diff = sqrt i' *. Float.two_pi *. 0.005 +. 0.6 in
+        let pos_angle = i' *. angle_diff in
+        let pos_rel = V2.(v pos_radius pos_angle |> of_polar) in
+        let pos = V2.(layer2_deps_center + pos_rel) in
+        let pos = { x = V2.x pos; y = V2.y pos } in
+        let text = layer2_dep.name in
+        let classes = [ layer2_dep.name; "layer2_dep" ] in
+        make_node ~pos ~radius:dot_radius ~text ~classes
+      )
+
+    (*goto implement as iterative search*)
+    let grid_pos ~cell_width i =
+      let open Gg in
+      let north = V2.v 0. cell_width in
+      let west  = V2.ortho north in
+      let south = V2.ortho west in
+      let east  = V2.ortho south
+      in
+      let rec aux i' len_side consumed_side dir pos_acc =
+        if i = i' then pos_acc else (
+          match dir with
+          | `East ->
+            if consumed_side = len_side then
+              aux i' len_side 0 `South pos_acc
+            else
+              aux (succ i') len_side (succ consumed_side) dir V2.(east + pos_acc)
+          | `South ->
+            if consumed_side = len_side then
+              aux i' len_side 0 `West pos_acc
+            else
+              aux (succ i') len_side (succ consumed_side) dir V2.(south + pos_acc)
+          | `West ->
+            if consumed_side = len_side then
+              aux i' len_side 0 `North pos_acc
+            else
+              aux (succ i') len_side (succ consumed_side) dir V2.(west + pos_acc)
+          | `North ->
+            if consumed_side = len_side then
+              (*> Note special case of jumping to next 'level'*)
+              aux (succ i') (len_side +2) 1 `East V2.(north + pos_acc)
+            else
+              aux (succ i') len_side (succ consumed_side) dir V2.(north + pos_acc)
+        )
+      in
+      aux 0 0 0 `East V2.(v 0. 0.)
+
+    let make_hitbox_square ~center_pos ~width ~text ~classes =
+      let title = make_title ~text in
+      (*> todo; why is this not in Tyxml - browser support missing?*)
+      let a_transform_origin = Svg.Unsafe.string_attrib "transform-origin" in
+      let a = Svg.[
+        a_class ("hitbox" :: classes);
+        a_transform_origin @@ sprintf "%f %f" center_pos.x center_pos.y;
+      ] in
+      Svg.g ~a (title :: make_square ~center_pos ~width)
+
+    let make_layer2_nodes_grid ~layer2_deps ~layer2_deps_center =
+      let open Gg in
+      let dot_radius = 0.005 in
+      let cell_width = dot_radius *. 2.5 in
+      layer2_deps |> List.mapi (fun i layer2_dep ->
+        let pos = V2.(layer2_deps_center + grid_pos ~cell_width i) in
+        let pos = { x = V2.x pos; y = V2.y pos } in
+        let text = layer2_dep.name in
+        let classes = [ layer2_dep.name; "layer2_dep" ] in
+        let visual_svg = make_node ~pos ~radius:dot_radius ~text ~classes in
+        let _hitbox_svg =
+          make_hitbox_square ~text ~classes
+            ~center_pos:pos
+            ~width:cell_width in
+        [ (* hitbox_svg;  *)visual_svg ]
+      )
+      |> List.flatten
+
+    let make_layer2_deps ~deps_w_positions =
+      let open Gg in
+      deps_w_positions |> List.mapi
+        (fun i ((dep, direct_dep_pos), layer2_deps) ->
+            let layer2_deps_center =
+              let direct_dep_pos = V2.(v direct_dep_pos.x direct_dep_pos.y) in
+              let center = V2.v center.x center.y in
+              let mult = if i mod 2 = 0 then 2.14 else 1.5
+              in
+              V2.(mult * (direct_dep_pos - center) + center)
+            in
+            let nodes = make_layer2_nodes_grid ~layer2_deps ~layer2_deps_center in
+            let bg =
+              let pos =
+                { x = V2.x layer2_deps_center; y = V2.y layer2_deps_center }
+              and radius = sqrt (float (List.length layer2_deps) +. 1.) *. 0.0115
+              and text = ""
+              and classes = [ "layer2_deps"; "bg"; dep.name ] in
+              make_node ~pos ~radius ~text ~classes
+            in
+            let edge =
+              let pos0 = direct_dep_pos in
+              let pos1 =
+                { x = V2.x layer2_deps_center; y = V2.y layer2_deps_center } in
+              let text = "" in
+              let classes = [ "layer2_deps" ] in
+              make_edge ~pos0 ~pos1 ~text ~classes
+            in
+            edge :: bg :: nodes
+        )
+      |> List.flatten
+
+    let make_shared_deps_css_aux ~dep ~shared_deps =
+      shared_deps |> Seq.map (fun shared_dep ->
+        sprintf {|
+.direct_dep.%s:hover ~ .node.layer2_dep.%s {
+  fill: #5454ff;
+}
+        |} dep.name shared_dep
+      )
+      |> List.of_seq
+      |> merge_css
+
+    let make_shared_deps_css ~deps_w_positions =
+      let module SSet = Set.Make(String) in
+      let sset_of_deps deps =
+        deps
+        |> List.map (fun dep -> dep.name)
+        |> SSet.of_list
+      in
+      let layer2_deps_sets =
+        deps_w_positions |> List.map (fun (_, layer2_deps) ->
+          layer2_deps |> sset_of_deps
+        )
+      in
+      deps_w_positions |> List.map (fun ((dep, _), layer2_deps) ->
+        let layer2_deps = sset_of_deps layer2_deps in
+        let shared_deps =
+          layer2_deps_sets
+          |> List.fold_left (fun acc layer2_deps' ->
+            SSet.(union acc (inter layer2_deps layer2_deps'))
+          ) SSet.empty
+          |> SSet.to_seq
+        in
+        make_shared_deps_css_aux ~dep ~shared_deps
+      )
+      |> merge_css
+
+    let make_deps (deps:assoc_graph) =
+      let deps_w_positions =
+        let open Gg in
+        let len_deps = List.length deps in
+        let diff_angle = Float.two_pi /. float len_deps in
+        deps |> List.mapi (fun i (dep, layer2_deps) ->
+          let angle = diff_angle *. float i in
+          let dist_center = 0.2 in
+          let x = cos angle *. dist_center +. center.x
+          and y = sin angle *. dist_center +. center.y in
+          ((dep, { x; y }), layer2_deps)
+        )
+      in
+      let direct_deps_edges, direct_deps_edges_css =
+        make_direct_deps_edges ~deps_w_positions
+      and direct_deps_nodes = make_direct_deps_nodes ~deps_w_positions
+      and layer2_deps = make_layer2_deps ~deps_w_positions
+      and shared_deps_css = make_shared_deps_css ~deps_w_positions
+      in
+      let svg = direct_deps_edges @ direct_deps_nodes @ layer2_deps in
+      let css = merge_css [ direct_deps_edges_css; shared_deps_css ] in
+      svg, css
+
+    let svg_defs = Svg.[ defs [
+      radialGradient ~a:[
+        a_id "gradient_01";
+        a_cx @@ Unit.none 0.5;
+        a_cy @@ Unit.none 0.5;
+        a_r @@ Unit.none 0.5;
+      ] [
+        stop ~a:[
+          a_offset @@ `Percentage 0.;
+          a_stop_color "bisque"
+        ] [];
+        stop ~a:[
+          a_offset @@ `Percentage 100.;
+          a_stop_color "bisque"; a_stop_opacity 0.
+        ] []
+      ]
+    ]]
+
+    let of_assoc (graph:assoc_graph) : _ output =
+      match graph with
+      | [] -> { svg_content = []; svg_attr = []; css = "" }
+      | (root_pkg, direct_deps) :: layer2_deps ->
+        let root_svg =
+          let pos = center
+          and radius = root_radius
+          and text =
+            sprintf "%s\nDirect dependencies: %d"
+              root_pkg.name (List.length direct_deps)
+          and classes = [ root_pkg.name; "root" ] in
+          make_node ~pos ~radius ~text ~classes
+        in
+        let deps_svgs, deps_css = make_deps layer2_deps in
+        let svg_attr = [ Svg.a_viewBox (0., 0., 1., 1.) ] in
+        let svg_content = svg_defs @ (root_svg :: deps_svgs) in
+        let css = merge_css [ initial_css; deps_css ] in
+        { svg_content; svg_attr; css }
+
+    let pp ppf html =
+      Format.fprintf ppf "%a@." (Tyxml_svg.pp ()) html
+
+  end
+
+  module Html = struct
+
+    module H = Tyxml_html
+
+    type t = H.doc
+
+    let merge_css = String.concat "\n"
+
+    let of_assoc ?(override_css="") (graph:assoc_graph) : t =
+      let svg = Svg.of_assoc graph in
+      H.html
+        (H.head
+            (H.title (H.txt "Dependencies"))
+            [H.style [H.Unsafe.data  @@ merge_css [ svg.css; override_css ]]]
+        )
+        (H.body [ H.svg ~a:svg.svg_attr svg.svg_content ])
+
+    let pp ppf html =
+      Format.fprintf ppf "%a@." (Tyxml_html.pp ()) html
+
+  end
+
+end