feat(docs): style playground chord selector as custom dropdown

apps/docs/components/playground/chord-selector.tsx

@@ -1,7 +1,9 @@
 "use client";
 
+import { useState, useRef, useEffect } from "react";
 import type { ChordId } from "@/lib/playground/types";
 import {
+  chordRegistry,
   majorChords,
   minorChords,
 } from "@/lib/playground/chord-registry";
@@ -13,35 +15,135 @@ export function ChordSelector({
   chordId: ChordId;
   onChange: (id: ChordId) => void;
 }) {
+  const [open, setOpen] = useState(false);
+  const containerRef = useRef<HTMLDivElement>(null);
+  const selected = chordRegistry[chordId];
+
+  useEffect(() => {
+    function handleClickOutside(e: MouseEvent) {
+      if (
+        containerRef.current &&
+        !containerRef.current.contains(e.target as Node)
+      ) {
+        setOpen(false);
+      }
+    }
+    if (open) {
+      document.addEventListener("mousedown", handleClickOutside);
+      return () =>
+        document.removeEventListener("mousedown", handleClickOutside);
+    }
+  }, [open]);
+
   return (
     <div className="rounded-xl border border-fd-border bg-fd-card p-4">
       <label className="mb-2 block text-xs font-medium uppercase tracking-wide text-fd-muted-foreground">
         Chord
       </label>
-      <select
-        value={chordId}
-        onChange={(e) => onChange(e.target.value as ChordId)}
-        className="w-full rounded-lg border border-fd-border bg-fd-background px-3 py-2 text-sm text-fd-foreground outline-none focus:ring-2 focus:ring-fd-primary/30"
-      >
-        <optgroup label="Major Chords">
-          {majorChords.map((c) => (
-            <option key={c.id} value={c.id}>
-              {c.name}
-            </option>
-          ))}
-        </optgroup>
-        <optgroup label="Minor Chords">
-          {minorChords.map((c) => (
-            <option key={c.id} value={c.id}>
-              {c.name}
-            </option>
-          ))}
-        </optgroup>
-      </select>
+      <div ref={containerRef} className="relative">
+        <button
+          type="button"
+          onClick={() => setOpen(!open)}
+          className="flex w-full items-center justify-between rounded-lg border border-fd-border bg-fd-background px-3 py-2 text-left text-sm text-fd-foreground outline-none transition-colors hover:bg-fd-background/50 focus:ring-2 focus:ring-fd-primary/30"
+        >
+          <span>{selected.name}</span>
+          <svg
+            className={`size-4 text-fd-muted-foreground transition-transform duration-200 ${open ? "rotate-180" : ""}`}
+            fill="none"
+            viewBox="0 0 24 24"
+            stroke="currentColor"
+            strokeWidth={2}
+          >
+            <path
+              strokeLinecap="round"
+              strokeLinejoin="round"
+              d="M19 9l-7 7-7-7"
+            />
+          </svg>
+        </button>
+
+        {open && (
+          <div
+            className="absolute left-0 right-0 top-full z-50 mt-1.5 max-h-72 overflow-y-auto rounded-xl border border-fd-border bg-fd-popover shadow-lg"
+            style={{
+              scrollbarWidth: "thin",
+              scrollbarColor: "rgba(127,127,127,0.3) transparent",
+            }}
+          >
+            <ChordGroup
+              label="Major Chords"
+              chords={majorChords}
+              activeId={chordId}
+              onSelect={(id) => {
+                onChange(id);
+                setOpen(false);
+              }}
+            />
+            <div className="mx-3 border-t border-fd-border" />
+            <ChordGroup
+              label="Minor Chords"
+              chords={minorChords}
+              activeId={chordId}
+              onSelect={(id) => {
+                onChange(id);
+                setOpen(false);
+              }}
+            />
+          </div>
+        )}
+      </div>
       <p className="mt-2 text-xs text-fd-muted-foreground">
-        {majorChords.find((c) => c.id === chordId)?.description ??
-          minorChords.find((c) => c.id === chordId)?.description}
+        {selected.description}
       </p>
     </div>
   );
 }
+
+function ChordGroup({
+  label,
+  chords,
+  activeId,
+  onSelect,
+}: {
+  label: string;
+  chords: { id: ChordId; name: string }[];
+  activeId: ChordId;
+  onSelect: (id: ChordId) => void;
+}) {
+  return (
+    <div className="p-1.5">
+      <div className="px-2.5 py-1.5 text-[11px] font-medium uppercase tracking-wider text-fd-muted-foreground">
+        {label}
+      </div>
+      {chords.map((c) => (
+        <button
+          key={c.id}
+          type="button"
+          onClick={() => onSelect(c.id)}
+          className={`flex w-full items-center rounded-lg px-2.5 py-1.5 text-sm transition-colors ${
+            c.id === activeId
+              ? "bg-fd-accent text-fd-accent-foreground font-medium"
+              : "text-fd-foreground hover:bg-fd-accent/50"
+          }`}
+        >
+          {c.name}
+          {c.id === activeId && (
+            <svg
+              className="ml-auto size-3.5 text-fd-primary"
+              fill="none"
+              viewBox="0 0 24 24"
+              stroke="currentColor"
+              strokeWidth={2.5}
+            >
+              <path
+                strokeLinecap="round"
+                strokeLinejoin="round"
+                d="M5 13l4 4L19 7"
+              />
+            </svg>
+          )}
+        </button>
+      ))}
+    </div>
+  );
+}