diff --git a/tl/resources/public/css/app.css b/tl/resources/public/css/app.css
new file mode 100644
index 0000000..74b4bf5
--- /dev/null
+++ b/tl/resources/public/css/app.css
@@ -0,0 +1,119 @@
+/* tl — app styles. Dynamic geometry (positions/sizes derived from zoom/frames
+   or the resizable panes) stays inline in the views; everything static is here. */
+
+html, body, #app { height: 100%; margin: 0; }
+body { overflow: hidden; }
+
+.app {
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+  font-family: sans-serif;
+  background: #0c0c0c;
+  color: #ddd;
+}
+
+/* --- top region: video | annotation ------------------------------------ */
+.top { display: flex; min-height: 0; }
+
+.video-pane {
+  flex-shrink: 0;
+  display: flex; align-items: center; justify-content: center;
+  background: #000; overflow: hidden; min-width: 0;
+}
+.video-pane video { max-width: 100%; max-height: 100%; display: block; background: #000; }
+
+.annot-pane { flex: 1; min-width: 0; display: flex; }
+
+/* --- draggable dividers ------------------------------------------------- */
+.divider-v { flex-shrink: 0; width: 6px; cursor: col-resize; background: #222; }
+.divider-h { flex-shrink: 0; height: 6px; cursor: row-resize; background: #222; }
+.divider-v:hover, .divider-h:hover { background: #3a6ea5; }
+
+/* --- commentary --------------------------------------------------------- */
+.commentary {
+  position: relative; flex: 1; overflow-y: auto;
+  background: #111; padding: 8px 12px; box-sizing: border-box;
+}
+.ann {
+  position: relative;
+  padding: 8px 10px; margin-bottom: 8px; border-radius: 4px;
+  border: 1px solid transparent; background: #161616;
+}
+.ann.active { border-color: #3a6ea5; background: #152333; }
+.ann-head { display: flex; align-items: center; justify-content: space-between;
+            gap: 8px; margin-bottom: 4px; }
+.ann-title { font-size: 10px; text-transform: uppercase; letter-spacing: 1px;
+             color: #7aa6d6; }
+.ann-empty { color: #666; font-size: 12px; }
+
+.jump-btn {
+  flex-shrink: 0; background: #1c2a38; color: #cfe3f5;
+  border: 1px solid #3a6ea5; border-radius: 4px;
+  padding: 1px 7px; cursor: pointer; font-size: 10px; white-space: nowrap;
+}
+/* native popover in the top layer; top/right set by JS (place-popover!) in
+   viewport coords so it tracks the commentary scroll. */
+.jump-pop:popover-open {
+  position: fixed;
+  margin: 0; inset: auto;
+  min-width: 150px; max-height: 180px; overflow-y: auto;
+  background: #1b1b1b; border: 1px solid #3a6ea5; border-radius: 4px;
+  box-shadow: 0 4px 14px rgba(0,0,0,0.5); padding: 4px;
+}
+.jump-pop button {
+  display: block; width: 100%; text-align: left; background: none;
+  color: #cde; border: none; border-radius: 3px; padding: 4px 6px;
+  cursor: pointer; font-size: 11px; white-space: nowrap;
+}
+.jump-pop button:hover { background: #2a4a6a; }
+
+/* --- markdown (tl.md output is wrapped in .md) -------------------------- */
+.md h1 { font-size: 16px; margin: 0 0 6px; line-height: 1.25; }
+.md h2 { font-size: 14px; margin: 0 0 6px; line-height: 1.25; }
+.md h3 { font-size: 13px; margin: 0 0 6px; line-height: 1.25; }
+.md h4, .md h5, .md h6 { font-size: 12px; margin: 0 0 6px; }
+.md p  { margin: 0 0 8px; }
+.md ul { margin: 0 0 8px 18px; padding: 0; }
+.md code { background: #222; padding: 0 3px; border-radius: 3px; font-size: 12px; }
+
+/* --- timeline region ---------------------------------------------------- */
+.timeline-pane { flex: 1; display: flex; flex-direction: column; min-height: 0; }
+
+.toolbar { display: flex; gap: 20px; align-items: center; padding: 6px 8px;
+           background: #0c0c0c; border-bottom: 1px solid #222; flex-shrink: 0; }
+.slider { display: flex; align-items: center; gap: 6px; font-size: 11px; color: #9ab; }
+.slider input { width: 150px; }
+
+.timeline-scroll { flex: 1; overflow-y: auto; overflow-x: hidden; min-height: 0; }
+.timeline { display: flex; align-items: flex-start; background: #111; }
+
+.gutter { flex-shrink: 0; width: 150px; user-select: none; }
+.gutter-label {
+  box-sizing: border-box;
+  border-bottom: 1px solid #2a2a2a; border-right: 1px solid #2a2a2a;
+  padding: 0 6px; font-size: 10px; color: #9ab; background: #141414;
+  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
+}
+.hscroll { overflow-x: auto; flex: 1; }
+.content { position: relative; cursor: ew-resize; }
+
+.track-row { position: relative; background: #1c1c1c; border-bottom: 1px solid #2a2a2a; }
+.clip {
+  position: absolute; top: 1px; box-sizing: border-box; overflow: hidden;
+  background: #3a6ea5; border: 1px solid #16324f; border-radius: 2px;
+  font-size: 10px; color: #cfe3f5; white-space: nowrap; padding-left: 3px;
+}
+
+.playhead { position: absolute; top: 0; bottom: 0; width: 2px; background: #e33;
+            z-index: 10; pointer-events: none; }
+.playhead-handle { position: absolute; top: 0; left: -5px; width: 12px; height: 10px;
+                   background: #e33; border-radius: 2px; }
+
+/* --- annotation lane ---------------------------------------------------- */
+.ann-lane-row { position: relative; height: 18px; }
+.ann-bar { position: absolute; top: 2px; height: 14px; border-radius: 2px; }
+.ann-bar-label { position: absolute; top: 1px; font-size: 9px; line-height: 16px;
+                 color: #eee; white-space: nowrap; pointer-events: none;
+                 text-shadow: 0 1px 2px #000; }
diff --git a/tl/resources/public/index.html b/tl/resources/public/index.html
index f75fb21..a9a0f93 100644
--- a/tl/resources/public/index.html
+++ b/tl/resources/public/index.html
@@ -4,6 +4,7 @@
     <meta charset='utf-8'>
     <meta name="viewport" content="width=device-width,initial-scale=1">
     <title>tl</title>
+    <link rel="stylesheet" href="/css/app.css">
   </head>
   <body>
     <noscript>
diff --git a/tl/src/tl/db.cljs b/tl/src/tl/db.cljs
index 3aef473..4962432 100644
--- a/tl/src/tl/db.cljs
+++ b/tl/src/tl/db.cljs
@@ -49,8 +49,11 @@
       :content "# Climax: the serve (slow-mo)\n\n3000+ frames on one motion. Time **dilates** at the decisive moment — the cut finally stops cutting and just *watches*."}}}
 
    ;; transient view state (mutates while scrubbing/zooming)
-   :view {:zoom          50           ; pixels per SECOND (px/frame = zoom/fps)
+   :view {:zoom          50           ; X zoom: pixels per SECOND (px/frame = zoom/fps)
+          :row-h         28           ; Y zoom: track row height in px
           :playhead      0.0          ; frames (media/display coordinate)
           :playing?      false
-          :seg           0            ; current segment index within the active program
-          :selected-clip nil}})
+          :selected-clip nil
+          ;; resizable layout (px): top region height, video pane width
+          :top-h         360
+          :video-w       560}})
diff --git a/tl/src/tl/events.cljs b/tl/src/tl/events.cljs
index a324981..5f19225 100644
--- a/tl/src/tl/events.cljs
+++ b/tl/src/tl/events.cljs
@@ -50,24 +50,22 @@
  (fn [db [_ playing?]]
    (assoc-in db [:view :playing?] playing?)))
 
-;; --- timeline stack (zoom into / out of a mark-group) --------------------
+;; --- timeline zoom (x = px/second, y = track row height) ----------------
 
 (rf/reg-event-db
- ::push-timeline
- (fn [db [_ gid]]
-   (-> db
-       (update-in [:marks :timeline-stack] conj gid)
-       (assoc-in [:view :seg] 0))))
+ ::set-zoom
+ (fn [db [_ px-per-sec]] (assoc-in db [:view :zoom] px-per-sec)))
 
 (rf/reg-event-db
- ::pop-timeline
- (fn [db _]
-   (-> db
-       (update-in [:marks :timeline-stack] #(if (> (count %) 1) (pop %) %))
-       (assoc-in [:view :seg] 0))))
+ ::set-row-h
+ (fn [db [_ h]] (assoc-in db [:view :row-h] h)))
+
+;; --- resizable layout ----------------------------------------------------
 
-;; current segment index within the active program (set by the player as it
-;; jumps from span to span)
 (rf/reg-event-db
- ::set-seg
- (fn [db [_ i]] (assoc-in db [:view :seg] i)))
+ ::set-top-h
+ (fn [db [_ h]] (assoc-in db [:view :top-h] h)))
+
+(rf/reg-event-db
+ ::set-video-w
+ (fn [db [_ w]] (assoc-in db [:view :video-w] w)))
diff --git a/tl/src/tl/md.cljs b/tl/src/tl/md.cljs
index 023a2b2..35ef457 100644
--- a/tl/src/tl/md.cljs
+++ b/tl/src/tl/md.cljs
@@ -24,15 +24,15 @@
 
 (defn- flush-para [out para]
   (if (seq para)
-    (conj out (into [:p {:style {:margin "0 0 8px"}}] (inline (str/join " " para))))
+    (conj out (into [:p] (inline (str/join " " para))))
     out))
 
 (defn render
-  "Markdown string -> a Hiccup [:div ...] tree."
+  "Markdown string -> a Hiccup [:div.md ...] tree (styled via the .md CSS rules)."
   [md]
   (loop [ls (str/split-lines (or md "")), out [], para []]
     (if (empty? ls)
-      (into [:div] (flush-para out para))
+      (into [:div.md] (flush-para out para))
       (let [t (str/trim (first ls))]
         (cond
           (str/blank? t)
@@ -43,8 +43,7 @@
                 txt (str/replace t #"^#+\s*" "")
                 tag (keyword (str "h" (min n 6)))]
             (recur (rest ls)
-                   (conj (flush-para out para)
-                         (into [tag {:style {:margin "0 0 6px" :lineHeight 1.25}}] (inline txt)))
+                   (conj (flush-para out para) (into [tag] (inline txt)))
                    []))
 
           (re-find #"^[-*]\s" t)
@@ -52,7 +51,7 @@
                 lis (for [it items]
                       (into [:li] (inline (str/replace (str/trim it) #"^[-*]\s*" ""))))]
             (recur more
-                   (conj (flush-para out para) (into [:ul {:style {:margin "0 0 8px 18px" :padding 0}}] lis))
+                   (conj (flush-para out para) (into [:ul] lis))
                    []))
 
           :else
diff --git a/tl/src/tl/subs.cljs b/tl/src/tl/subs.cljs
index 1567f25..d364b7a 100644
--- a/tl/src/tl/subs.cljs
+++ b/tl/src/tl/subs.cljs
@@ -54,41 +54,10 @@
    (:id (or (last (filter #(<= (:anchor %) ph) anns))
             (first anns)))))
 
-;; --- playback program (the active timeline as an ordered EDL) ------------
-(rf/reg-sub ::current-timeline-id :<- [::timeline-stack] (fn [st] (last st)))
-(rf/reg-sub ::seg (fn [db] (get-in db [:view :seg])))
-
-(defn- ->segments
-  "Lay spans end-to-end in virtual time, tagging each with its virtual offset."
-  [spans]
-  (loop [v 0, ss spans, out []]
-    (if-let [s (first ss)]
-      (let [len (max 1 (- (:end s) (:start s)))]
-        (recur (+ v len) (rest ss)
-               (conj out (assoc s :virt-start v :virt-len len :virt-end (+ v len)))))
-      out)))
-
-;; A program = ordered segments {:start :end (media) :virt-start :virt-len :virt-end :track}.
-;; :root (or any timeline without :marks) plays the whole media linearly as one
-;; segment; a pushed mark-group plays its resolved spans, jumping between them.
-(rf/reg-sub
- ::program
- :<- [::current-timeline-id] :<- [::groups] :<- [::clip-index] :<- [::duration]
- (fn [[gid groups idx dur] _]
-   (cond
-     (nil? dur)
-     {:root? true :id gid :segments [] :virt-len 0}
-
-     (or (= gid :root) (nil? (:marks (get groups gid))))
-     {:root? true :id gid :virt-len dur
-      :segments [{:start 0 :end dur :virt-start 0 :virt-len dur :virt-end dur :track "Sequence"}]}
-
-     :else
-     (let [segs (->segments (marks/resolve-group idx groups gid))]
-       {:root? false :id gid :segments segs
-        :virt-len (reduce + 0 (map :virt-len segs))}))))
-
 ;; --- view state (frames in; views multiply by zoom for pixels) ---
-(rf/reg-sub ::zoom     (fn [db] (get-in db [:view :zoom])))      ; px per second
+(rf/reg-sub ::zoom     (fn [db] (get-in db [:view :zoom])))      ; X: px per second
+(rf/reg-sub ::row-h    (fn [db] (get-in db [:view :row-h])))     ; Y: track row height px
 (rf/reg-sub ::playhead (fn [db] (get-in db [:view :playhead]))) ; frames
 (rf/reg-sub ::playing? (fn [db] (get-in db [:view :playing?])))
+(rf/reg-sub ::top-h    (fn [db] (get-in db [:view :top-h])))    ; layout: top region height
+(rf/reg-sub ::video-w  (fn [db] (get-in db [:view :video-w]))) ; layout: video pane width
diff --git a/tl/src/tl/views.cljs b/tl/src/tl/views.cljs
index a7e414f..4db93fe 100644
--- a/tl/src/tl/views.cljs
+++ b/tl/src/tl/views.cljs
@@ -6,7 +6,6 @@
    [tl.md :as md]
    [tl.events :as events]))
 
-(def ^:const row-h 28)
 ;; Served by dev/media_server.py (range-capable) rather than shadow's :dev-http,
 ;; which doesn't do byte-range serving — Safari/iOS won't play <video> without it.
 ;; Host-relative so it works over localhost and Tailscale alike.
@@ -20,6 +19,14 @@
 
 (defn- secs [frames fps] (/ frames fps))
 
+(defn- tc
+  "frames -> m:ss timecode string."
+  [frames fps]
+  (let [s   (/ frames fps)
+        m   (js/Math.floor (/ s 60))
+        sec (js/Math.floor (mod s 60))]
+    (str m ":" (when (< sec 10) "0") sec)))
+
 (defn- center-on-playhead! [fps zoom playhead]
   (when-let [el @scroll-el]
     (let [px     (* (secs playhead fps) zoom)
@@ -31,219 +38,176 @@
   (when-let [v @video-el]
     (set! (.-currentTime v) (secs frames fps))))
 
+(defn- jump! [fps frame]
+  (rf/dispatch [::events/set-playhead frame])
+  (seek-to-frame! fps frame))
+
 (defn- toggle-play! []
   (when-let [v @video-el]
     (if (.-paused v) (.play v) (.pause v))))   ; play/pause events drive :playing? + rAF
 
+(defn- editable-target?
+  "True for fields where Space should type a space, not toggle play."
+  [el]
+  (let [tag (some-> el .-tagName)]
+    (or (= "TEXTAREA" tag)
+        (and (= "INPUT" tag)
+             (not (#{"range" "checkbox" "radio" "button"} (.-type el))))
+        (boolean (and el (.-isContentEditable el))))))
+
 (defn- on-keydown [e]
-  ;; Space toggles play. If the <video> itself is focused, let its native
-  ;; control handle it so we don't double-toggle.
+  ;; Space = play/pause globally. preventDefault stops it from scrolling the
+  ;; page or activating a focused button (and from the <video>'s own native
+  ;; toggle, so we never double-fire). (Jump popovers are native — they
+  ;; light-dismiss and Escape-close themselves.)
   (when (and (= "Space" (.-code e))
-             (not= @video-el (.-activeElement js/document)))
+             (not (editable-target? (.-target e))))
     (.preventDefault e)
     (toggle-play!)))
 
-(defonce ^:private _kbd
-  (.addEventListener js/document "keydown" on-keydown))
+;; Re-bind on every (re)load so the live handler is the one attached —
+;; defonce alone would keep a stale listener across hot reloads.
+(defonce ^:private kbd (atom nil))
+(when-let [h @kbd] (.removeEventListener js/document "keydown" h))
+(reset! kbd on-keydown)
+(.addEventListener js/document "keydown" on-keydown)
 
 (defn video-monitor
-  "Native-controls <video> that plays the active *program*. A program is an
-  ordered list of source spans; while playing, a rAF loop pushes currentTime
-  (media frames) into :playhead AND, when it reaches the end of the current
-  span, seeks the video to the next span's source frame — so a pushed
-  sub-timeline plays its clips back-to-back, jumping across the source media.
-  :root plays the whole media as one span (unchanged behaviour)."
+  "Native-controls <video> that acts as the playback clock: while it's playing,
+  a requestAnimationFrame loop pushes currentTime (as frames) into :playhead.
+  Also syncs on seek/pause so scrubbing (native controls or the timeline) moves
+  the playhead. Sized by CSS (.video-pane video) to fit its pane."
   [fps]
-  (let [raf  (atom nil)
-        prog (atom nil)        ; latest program (mirrored from the sub each render)
-        seg  (atom 0)          ; current segment index (hot path)
-        prev (atom :init)      ; previous program id, to detect push/pop
-        seek!  (fn [frame] (when-let [v @video-el]
-                             (set! (.-currentTime v) (secs frame fps))))
-        push!  (fn [] (when-let [v @video-el]
-                        (rf/dispatch [::events/set-playhead (* (.-currentTime v) fps)])))
-        tick (fn tick []
-               (when-let [v @video-el]
-                 (let [segs (:segments @prog)
-                       i    @seg
-                       cur  (get segs i)
-                       mf   (* (.-currentTime v) fps)]
-                   (when cur
-                     (when (>= mf (- (:end cur) 0.5))     ; reached end of this span
-                       (if (< (inc i) (count segs))
-                         (do (reset! seg (inc i))
-                             (rf/dispatch [::events/set-seg (inc i)])
-                             (seek! (:start (get segs (inc i)))))
-                         (when-not (:root? @prog) (.pause v)))) ; end of program
-                     (rf/dispatch [::events/set-playhead mf]))))
-               (reset! raf (js/requestAnimationFrame tick)))
+  (let [raf (atom nil)
+        push! (fn [] (when-let [v @video-el]
+                       (rf/dispatch [::events/set-playhead (* (.-currentTime v) fps)])))
+        tick (fn tick [] (push!) (reset! raf (js/requestAnimationFrame tick)))
         stop (fn [] (when @raf (js/cancelAnimationFrame @raf) (reset! raf nil)))]
     (fn [_fps]
-      (let [program @(rf/subscribe [::subs/program])]
-        (reset! prog program)
-        ;; entered a different timeline: reset to its first span (and try to play)
-        (when (not= (:id program) @prev)
-          (reset! prev (:id program))
-          (reset! seg 0)
-          (when-not (:root? program)
-            (r/after-render
-             (fn []
-               (seek! (:start (first (:segments program))))
-               (when-let [v @video-el] (-> (.play v) (.catch (fn [_]))))))))
-        [:video {:src       media-src
-                 :controls  true
-                 ;; Keep playback inline on iOS instead of jumping to the
-                 ;; native fullscreen player.
-                 :plays-inline      true
-                 :webkit-playsinline "true"
-                 :ref       (fn [node] (reset! video-el node))
-                 :on-play   (fn [_] (reset! following? true)
-                                    (rf/dispatch [::events/set-playing true])  (stop) (tick))
-                 :on-pause  (fn [_] (rf/dispatch [::events/set-playing false]) (stop) (push!))
-                 :on-seeked (fn [_] (push!))
-                 :style {:width 480 :display :block :background "#000"}}]))))
+      [:video {:src       media-src
+               :controls  true
+               ;; Keep playback inline on iOS instead of jumping to fullscreen.
+               :plays-inline       true
+               :webkit-playsinline "true"
+               :ref       (fn [node] (reset! video-el node))
+               :on-play   (fn [_] (reset! following? true)
+                                  (rf/dispatch [::events/set-playing true])  (stop) (tick))
+               :on-pause  (fn [_] (rf/dispatch [::events/set-playing false]) (stop) (push!))
+               :on-seeked (fn [_] (push!))}])))
 
-;; --- annotation layer -----------------------------------------------------
+;; --- commentary sidebar ---------------------------------------------------
 
-(def ^:private ann-colors ["#c2554e" "#4e8fc2" "#5ab07a" "#b08a3a" "#8a5ab0" "#3aa0a0"])
+(defn- jump-targets
+  "One jump option per span: {:frame :label}, label = setup name · timecode."
+  [fps nm spans]
+  (for [s spans]
+    {:frame (:start s)
+     :label (str (or (:track (:clip s)) nm) " · " (tc (:start s) fps))}))
 
-(defn annotation-lane
-  "One labeled row per annotation, drawn above the tracks. Bars are positioned
-  in display frames (same coordinate as clips), so they align with the timeline."
-  [fps zoom annotations active]
-  [:div {:style {:position :relative}}
-   (doall
-    (map-indexed
-     (fn [i {:keys [id name spans] :as _ann}]
-       (let [color (nth ann-colors (mod i (count ann-colors)))
-             on?   (= id active)]
-         ^{:key id}
-         [:div {:style {:position :relative :height 18}}
-          (for [[j s] (map-indexed vector spans)]
-            (let [left (* (secs (:start s) fps) zoom)
-                  w    (* (secs (- (:end s) (:start s)) fps) zoom)]
-              ^{:key j}
-              [:div {:title name
-                     :style {:position :absolute :left left :top 2 :height 14
-                             :width (max 3 w)
-                             :background (if on? color (str color "80"))
-                             :border (str "1px solid " color) :border-radius 2}}]))
-          (when-let [a (some-> spans first :start)]
-            [:div {:style {:position :absolute :left (+ 4 (* (secs a fps) zoom)) :top 1
-                           :font-size 9 :line-height "16px" :color "#eee"
-                           :white-space :nowrap :pointer-events :none
-                           :text-shadow "0 1px 2px #000"}}
-             name])]))
-     annotations))])
+(defn- place-popover!
+  "Anchor a native popover under its trigger button, in viewport coords (so it
+  tracks the commentary's scroll). anchor() CSS misbehaves inside a scroll box."
+  [pop]
+  (when-let [btn (.querySelector js/document (str "[popovertarget='" (.-id pop) "']"))]
+    (let [r (.getBoundingClientRect btn)]
+      (set! (.. pop -style -top)   (str (+ (.-bottom r) 4) "px"))
+      (set! (.. pop -style -right) (str (- (.-innerWidth js/window) (.-right r)) "px"))
+      (set! (.. pop -style -left)  "auto"))))
+
+(defn- position-popover-ref
+  "Ref for a .jump-pop: position it just before it opens (beforetoggle fires
+  pre-paint, so there's no flash from the default position)."
+  [node]
+  (when node
+    (.addEventListener node "beforetoggle"
+                       (fn [e] (when (= "open" (.-newState e)) (place-popover! node))))))
 
 (defn commentary
-  "Markdown commentary sidebar. Each annotation is a block anchored to its start
-  frame; the active one is highlighted and scrolled to ~1/3 from the top as the
-  video plays."
+  "Markdown commentary. Each annotation is a block anchored to its start frame;
+  the active one is highlighted and scrolled into view. A jump button seeks to
+  the annotation's start — or opens a popover of starts if it has several."
   []
-  (let [el (atom nil)]
+  (let [el (atom nil)]                           ; scroll container (no reactivity needed)
     (fn []
       (let [anns   @(rf/subscribe [::subs/annotations])
-            active @(rf/subscribe [::subs/active-annotation])]
+            active @(rf/subscribe [::subs/active-annotation])
+            fps    @(rf/subscribe [::subs/fps])]
         (r/after-render
          (fn []
            (when-let [c @el]
              (when-let [node (and active (.querySelector c (str "#ann-" (name active))))]
                (set! (.-scrollTop c) (max 0 (- (.-offsetTop node) (/ (.-clientHeight c) 3))))))))
-        [:div {:ref (fn [n] (reset! el n))
-               :style {:position :relative :width 360 :height 270 :overflow-y :auto
-                       :background "#111" :border "1px solid #333" :border-radius 4
-                       :padding "8px 12px" :box-sizing :border-box}}
+        [:div.commentary {:ref (fn [n] (reset! el n))}
          (if (seq anns)
-           (for [{:keys [id content instant?] nm :name} anns]
-             ^{:key id}
-             [:div {:id (str "ann-" (name id))
-                    :style {:padding "8px 10px" :margin-bottom 8 :border-radius 4
-                            :border (if (= id active) "1px solid #3a6ea5" "1px solid transparent")
-                            :background (if (= id active) "#152333" "#161616")}}
-              [:div {:style {:display :flex :align-items :center :justify-content :space-between
-                             :margin-bottom 4}}
-               [:div {:style {:font-size 10 :text-transform :uppercase :letter-spacing 1
-                              :color "#7aa6d6"}} nm]
-               (when-not instant?
-                 [:button {:on-click #(rf/dispatch [::events/push-timeline id])
-                           :title "Play these shots back-to-back"
-                           :style {:background "#1c2a38" :color "#cfe3f5"
-                                   :border "1px solid #3a6ea5" :border-radius 4
-                                   :padding "1px 7px" :cursor :pointer :font-size 10}}
-                  "▶ zoom in"])]
-              [md/render content]])
-           [:div {:style {:color "#666" :font-size 12}} "No annotations."])]))))
+           (doall
+            (for [{:keys [id content spans] nm :name} anns]
+             (let [targets (vec (jump-targets fps nm spans))
+                   one?    (= 1 (count targets))]
+               ^{:key id}
+               [:div.ann {:id (str "ann-" (name id))
+                          :class (when (= id active) "active")}
+                [:div.ann-head
+                 [:div.ann-title nm]
+                 (if one?
+                   [:button.jump-btn
+                    {:on-click #(jump! fps (:frame (first targets)))} "↪ jump"]
+                   ;; native popover: the button toggles it; the browser
+                   ;; handles light-dismiss + Escape + top-layer. Positioning is
+                   ;; the one bit of JS (anchor() misbehaves in a scroll box).
+                   [:button.jump-btn {:popovertarget (str "jp-" (name id))}
+                    (str "↪ jump (" (count targets) ")")])]
+                (when-not one?
+                  [:div.jump-pop {:popover "auto" :id (str "jp-" (name id))
+                                  :ref position-popover-ref}
+                   (for [[k t] (map-indexed vector targets)]
+                     ^{:key k}
+                     [:button {:popovertarget (str "jp-" (name id))
+                               :popovertargetaction "hide"
+                               :on-click #(jump! fps (:frame t))}
+                      (:label t)])])
+                [md/render content]])))
+           [:div.ann-empty "No annotations."])]))))
 
-;; --- timeline stack: zoom into a mark-group + program strip ---------------
+;; --- timeline -------------------------------------------------------------
 
-(defn breadcrumb []
-  (let [stack  @(rf/subscribe [::subs/timeline-stack])
-        groups @(rf/subscribe [::subs/groups])]
-    [:div {:style {:display :flex :align-items :center :gap 8 :margin-bottom 8
-                   :font-size 12 :min-height 24}}
-     (when (> (count stack) 1)
-       [:button {:on-click #(rf/dispatch [::events/pop-timeline])
-                 :style {:background "#222" :color "#cfe3f5" :border "1px solid #3a6ea5"
-                         :border-radius 4 :padding "2px 8px" :cursor :pointer :font-size 11}}
-        "← back"])
-     (into [:div {:style {:display :flex :gap 6 :align-items :center}}]
-           (map-indexed
-            (fn [i gid]
-              ^{:key i}
-              [:span (when (pos? i) {})
-               (when (pos? i) [:span {:style {:color "#555" :margin-right 6}} "›"])
-               [:span {:style {:color (if (= gid (last stack)) "#cfe3f5" "#888")}}
-                (get-in groups [gid :name] (name gid))]])
-            stack))]))
+(def ^:private ann-colors ["#c2554e" "#4e8fc2" "#5ab07a" "#b08a3a" "#8a5ab0" "#3aa0a0"])
 
-(defn program-strip
-  "Contiguous view of the active sub-timeline: each source span laid end-to-end
-  in virtual time, current span highlighted, smooth virtual playhead."
-  []
-  (let [program  @(rf/subscribe [::subs/program])
-        seg      @(rf/subscribe [::subs/seg])
-        playhead @(rf/subscribe [::subs/playhead])]
-    (when-not (:root? program)
-      (let [segs (:segments program)
-            vlen (max 1 (:virt-len program))
-            w    852
-            sc   (/ w vlen)
-            cur  (get segs seg)
-            vp   (when cur (+ (:virt-start cur) (- playhead (:start cur))))]
-        [:div {:style {:position :relative :width w :height 34 :margin-bottom 12
-                       :background "#111" :border "1px solid #333" :border-radius 4
-                       :overflow :hidden}}
-         (for [[i s] (map-indexed vector segs)]
-           ^{:key i}
-           [:div {:style {:position :absolute :top 0 :bottom 0
-                          :left (* (:virt-start s) sc)
-                          :width (max 1 (- (* (:virt-len s) sc) 1))
-                          :background (if (= i seg) "#2a4a6a" "#1c2a38")
-                          :box-sizing :border-box :overflow :hidden
-                          :font-size 9 :color "#bcd" :padding "3px 4px" :white-space :nowrap}}
-            (:track s)])
-         (when vp
-           [:div {:style {:position :absolute :top 0 :bottom 0 :left (* vp sc)
-                          :width 2 :background "#e33" :pointer-events :none}}])]))))
+(defn annotation-lane
+  "One labeled row per annotation, above the tracks. Bars are positioned in
+  display frames (same coordinate as clips), so they align with the timeline."
+  [fps zoom annotations active]
+  [:div
+   (doall
+    (map-indexed
+     (fn [i {:keys [id name spans]}]
+       (let [color (nth ann-colors (mod i (count ann-colors)))
+             on?   (= id active)]
+         ^{:key id}
+         [:div.ann-lane-row
+          (for [[j s] (map-indexed vector spans)]
+            (let [left (* (secs (:start s) fps) zoom)
+                  w    (* (secs (- (:end s) (:start s)) fps) zoom)]
+              ^{:key j}
+              [:div.ann-bar
+               {:title name
+                :style {:left left :width (max 3 w)
+                        :background (if on? color (str color "80"))
+                        :border (str "1px solid " color)}}]))
+          (when-let [a (some-> spans first :start)]
+            [:div.ann-bar-label {:style {:left (+ 4 (* (secs a fps) zoom))}} name])]))
+     annotations))])
 
-(defn clip-block [fps zoom {:keys [name media-in duration] :as _clip}]
+(defn clip-block [fps zoom row-h {:keys [name media-in duration] :as _clip}]
   (let [left  (* (secs media-in fps) zoom)
         width (max 1 (* (secs duration fps) zoom))]
-    [:div {:style {:position :absolute :left left :top 1
-                   :width width :height (- row-h 2)
-                   :box-sizing :border-box :overflow :hidden
-                   :background "#3a6ea5" :border "1px solid #16324f"
-                   :border-radius 2 :font-size 10 :line-height "26px"
-                   :color "#cfe3f5" :white-space :nowrap :padding-left 3}}
+    [:div.clip {:style {:left left :width width :height (- row-h 2)
+                        :line-height (str (- row-h 2) "px")}}
      name]))
 
-(defn track-row [fps zoom track]
-  [:div {:style {:position :relative :height row-h
-                 :background (if (= :audio (:kind track)) "#161616" "#1c1c1c")
-                 :border-bottom "1px solid #2a2a2a"}}
+(defn track-row [fps zoom row-h track]
+  [:div.track-row {:style {:height row-h}}
    (for [c (:clips track)]
-     ^{:key (:id c)} [clip-block fps zoom c])])
+     ^{:key (:id c)} [clip-block fps zoom row-h c])])
 
 (defn- ev->frames
   "Pointer clientX -> clamped timeline frame, relative to the content div
@@ -270,13 +234,12 @@
     (.addEventListener js/document "mousemove" move)
     (.addEventListener js/document "mouseup" up)))
 
-(def ^:private gutter-w 150)
-
 (defn timeline []
   (let [content (atom nil)]
     (fn []
       (let [fps      @(rf/subscribe [::subs/fps])
             zoom     @(rf/subscribe [::subs/zoom])
+            row-h    @(rf/subscribe [::subs/row-h])
             duration @(rf/subscribe [::subs/duration])
             tracks   @(rf/subscribe [::subs/tracks])
             playhead @(rf/subscribe [::subs/playhead])
@@ -288,48 +251,92 @@
             width    (* (secs duration fps) zoom)]
         (when (and playing? @following?)
           (r/after-render #(center-on-playhead! fps zoom playhead)))
-        [:div {:style {:display :flex :align-items :flex-start
-                       :border "1px solid #333" :background "#111"}}
+        [:div.timeline
          ;; fixed left gutter: setup (track) names, always visible
-         [:div {:style {:flex-shrink 0 :width gutter-w :user-select :none}}
+         [:div.gutter
           [:div {:style {:height lane-h}}]   ; spacer aligning labels with rows
           (for [t vtracks]
             ^{:key (:id t)}
-            [:div {:style {:height row-h :box-sizing :border-box
-                           :border-bottom "1px solid #2a2a2a" :border-right "1px solid #2a2a2a"
-                           :padding "0 6px" :font-size 10 :line-height (str (dec row-h) "px")
-                           :color "#9ab" :background "#141414"
-                           :white-space :nowrap :overflow :hidden :text-overflow :ellipsis}}
+            [:div.gutter-label {:style {:height row-h :line-height (str (dec row-h) "px")}}
              (:name t)])]
          ;; horizontally-scrolling timeline
-         [:div {:ref (fn [n] (reset! scroll-el n))
-                :on-wheel (fn [_] (reset! following? false))
-                :style {:overflow-x :auto :flex 1}}
-          [:div {:ref (fn [n] (reset! content n))
-                 :on-mouse-down (fn [e] (begin-scrub! @content zoom fps duration e))
-                 :style {:position :relative :width width :cursor "ew-resize"}}
-           ;; playhead: line spanning all rows + a grab handle at the top
+         [:div.hscroll {:ref (fn [n] (reset! scroll-el n))
+                        :on-wheel (fn [_] (reset! following? false))}
+          [:div.content {:ref (fn [n] (reset! content n))
+                         :on-mouse-down (fn [e] (begin-scrub! @content zoom fps duration e))
+                         :style {:width width}}
            (let [x (* (secs playhead fps) zoom)]
-             [:div {:style {:position :absolute :top 0 :bottom 0 :left x
-                            :width 2 :background "#e33" :z-index 10
-                            :pointer-events "none"}}
-              [:div {:style {:position :absolute :top 0 :left -5 :width 12 :height 10
-                             :background "#e33" :border-radius 2}}]])
+             [:div.playhead {:style {:left x}}
+              [:div.playhead-handle]])
            [annotation-lane fps zoom anns active]
            (for [t vtracks]
-             ^{:key (:id t)} [track-row fps zoom t])]]]))))
+             ^{:key (:id t)} [track-row fps zoom row-h t])]]]))))
+
+;; --- zoom + layout shell --------------------------------------------------
+
+(defn- slider [label v lo hi on]
+  [:label.slider label
+   [:input {:type "range" :min lo :max hi :value v
+            :on-change #(on (js/parseFloat (.. % -target -value)))}]])
+
+(defn- zoom-x!
+  "Set X zoom while keeping the playhead pinned to its on-screen position
+  (Resolve-style: zoom around the playhead, not the left edge)."
+  [z1]
+  (let [el  @scroll-el
+        fps @(rf/subscribe [::subs/fps])
+        ph  @(rf/subscribe [::subs/playhead])
+        z0  @(rf/subscribe [::subs/zoom])]
+    (rf/dispatch [::events/set-zoom z1])
+    (when el
+      (let [target (max 0 (+ (.-scrollLeft el) (* (secs ph fps) (- z1 z0))))]
+        (r/after-render #(set! (.-scrollLeft el) target))))))
+
+(defn zoom-controls []
+  (let [zoom  @(rf/subscribe [::subs/zoom])
+        row-h @(rf/subscribe [::subs/row-h])]
+    [:div.toolbar
+     [slider "Zoom X" zoom 2 400 zoom-x!]
+     [slider "Zoom Y" row-h 8 120 #(rf/dispatch [::events/set-row-h %])]]))
+
+(defn- begin-resize!
+  "Drag a divider: dispatches `evt` with the new size, clamped to [lo hi]."
+  [axis evt cur lo hi ev]
+  (.preventDefault ev)
+  (let [p0   (if (= axis :x) (.-clientX ev) (.-clientY ev))
+        move (fn [e]
+               (let [p (if (= axis :x) (.-clientX e) (.-clientY e))
+                     n (-> (+ cur (- p p0)) (max lo) (min hi))]
+                 (rf/dispatch-sync [evt n])))
+        up   (fn up [_]
+               (.removeEventListener js/document "mousemove" move)
+               (.removeEventListener js/document "mouseup" up))]
+    (.addEventListener js/document "mousemove" move)
+    (.addEventListener js/document "mouseup" up)))
 
 (defn main-panel []
-  (let [status @(rf/subscribe [::subs/load-status])
-        fps    (or @(rf/subscribe [::subs/fps]) (/ 24000 1001))]
-    [:div {:style {:font-family "sans-serif" :background "#0c0c0c"
-                   :color "#ddd" :min-height "100vh" :padding 12}}
-     [breadcrumb]
-     [program-strip]
-     [:div {:style {:display :flex :gap 12 :align-items :flex-start :margin-bottom 12}}
-      [video-monitor fps]
-      [commentary]]
-     (case status
-       :ready [timeline]
-       :error [:div {:style {:color "#e66"}} "Failed to load OTIO"]
-       [:div "Loading timeline…"])]))
+  (let [status  @(rf/subscribe [::subs/load-status])
+        fps     (or @(rf/subscribe [::subs/fps]) (/ 24000 1001))
+        top-h   @(rf/subscribe [::subs/top-h])
+        video-w @(rf/subscribe [::subs/video-w])]
+    [:div.app
+     ;; top region: video | annotation
+     [:div.top {:style {:height top-h}}
+      [:div.video-pane {:style {:width video-w}}
+       [video-monitor fps]]
+      [:div.divider-v
+       {:on-mouse-down #(begin-resize! :x ::events/set-video-w video-w
+                                       220 (- (.-innerWidth js/window) 280) %)}]
+      [:div.annot-pane [commentary]]]
+     ;; horizontal divider
+     [:div.divider-h
+      {:on-mouse-down #(begin-resize! :y ::events/set-top-h top-h
+                                      140 (- (.-innerHeight js/window) 160) %)}]
+     ;; timeline region
+     [:div.timeline-pane
+      [zoom-controls]
+      [:div.timeline-scroll
+       (case status
+         :ready [timeline]
+         :error [:div {:style {:color "#e66" :padding 12}} "Failed to load OTIO"]
+         [:div {:style {:padding 12}} "Loading timeline…"])]]]))