diff --git a/src/App.tsx b/src/App.tsx
index a30e1b6..44c15f2 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -2,6 +2,7 @@ import { useState } from 'react'
 import './App.css'
 import { TicTacToe } from './showcase/tic-tac-toe/TicTacToe'
 import CssPlayground from './showcase/css-playground/CssPlayground';
+import { Collapsible } from './showcase/collapsible/Collapsible';
 
 function App() {
     const [path, setPath] = useState(localStorage.getItem("route") || "/");
@@ -17,6 +18,7 @@ function App() {
                 <button onClick={() => changeRoute("/")}>Home</button>
                 <button onClick={() => changeRoute("/tic-tac-toe")}>Tic Tac Toe</button>
                 <button onClick={() => changeRoute("/css-playground")}>CSS Playground</button>
+                <button onClick={() => changeRoute("/collapsible")}>Collapsible</button>
             </nav>
             <main role="main">
                 {
@@ -43,6 +45,13 @@ function App() {
                         <CssPlayground />
                     </section>
                 }
+                {
+                    path === "/collapsible" &&
+
+                    <section>
+                        <Collapsible />
+                    </section>
+                }
             </main>
         </div >
     )
diff --git a/src/showcase/collapsible/Collapsible.tsx b/src/showcase/collapsible/Collapsible.tsx
new file mode 100644
index 0000000..d12d1a9
--- /dev/null
+++ b/src/showcase/collapsible/Collapsible.tsx
@@ -0,0 +1,224 @@
+import { useId, useState } from 'react';
+
+interface CollapsiblePanelProps {
+    title: string;
+    children: React.ReactNode;
+}
+
+function CollapsiblePanel({ title, children }: CollapsiblePanelProps) {
+    const [isOpen, setIsOpen] = useState(false);
+    const contentId = useId();
+
+    return (
+        <div
+            className={`border-r border-gray-300 flex flex-col overflow-hidden ${isOpen ? 'flex-1 min-w-48' : 'w-8'}`}
+        >
+            <button
+                type="button"
+                aria-expanded={isOpen}
+                aria-controls={contentId}
+                onClick={() => setIsOpen(!isOpen)}
+                className="text-left font-mono text-sm font-bold p-1 hover:bg-gray-100 cursor-pointer flex-shrink-0"
+                style={isOpen ? undefined : { writingMode: 'vertical-rl', transform: 'rotate(180deg)' }}
+            >
+                {isOpen ? `- ${title}` : title}
+            </button>
+            {isOpen && (
+                <div id={contentId} className="p-2 overflow-auto flex-1 font-mono text-sm whitespace-pre">
+                    {children}
+                </div>
+            )}
+        </div>
+    );
+}
+
+const PANELS: { title: string; content: string }[] = [
+    {
+        title: 'InterMutationAliasingEffects',
+        content: `// InterMutationAliasingEffects pass
+// Tracks aliasing relationships between mutable values
+// across mutations to ensure correctness.
+
+function analyze(fn) {
+  const aliases = new Map();
+  for (const instr of fn.body) {
+    trackAliases(instr, aliases);
+  }
+  return aliases;
+}`,
+    },
+    {
+        title: 'AnalyseFunctions',
+        content: `// AnalyseFunctions pass
+// Analyses each function definition to collect
+// metadata: side-effects, captured variables, etc.
+
+function analyseFunctions(program) {
+  for (const fn of program.functions) {
+    fn.meta = collectMeta(fn);
+  }
+}`,
+    },
+    {
+        title: 'OptimizePropsMethodCalls',
+        content: `// OptimizePropsMethodCalls pass
+// Replaces repeated props.foo() calls with a
+// cached local variable where safe to do so.
+
+function optimize(fn) {
+  const cache = new Map();
+  rewrite(fn.body, cache);
+}`,
+    },
+    {
+        title: 'InferTypes',
+        content: `// InferTypes pass
+// Infers types for SSA values using a simple
+// fixed-point dataflow algorithm.
+
+function inferTypes(fn) {
+  let changed = true;
+  while (changed) {
+    changed = propagate(fn);
+  }
+}`,
+    },
+    {
+        title: 'ConstantPropagation',
+        content: `// ConstantPropagation pass
+// Replaces uses of known-constant SSA values
+// with their literal values.
+
+function constantProp(fn) {
+  const constants = findConstants(fn);
+  substitute(fn.body, constants);
+}`,
+    },
+    {
+        title: 'EliminateRedundantPhi',
+        content: `// EliminateRedundantPhi pass
+// Removes phi nodes whose all operands are
+// the same value.
+
+function eliminateRedundantPhi(fn) {
+  for (const block of fn.blocks) {
+    block.phis = block.phis.filter(phi =>
+      !allSame(phi.operands)
+    );
+  }
+}`,
+    },
+    {
+        title: 'SSA',
+        content: `// SSA (Static Single Assignment) pass
+// Converts the IR into SSA form by inserting
+// phi nodes at join points.
+
+function toSSA(fn) {
+  const dominators = computeDominators(fn);
+  insertPhis(fn, dominators);
+  renameVariables(fn);
+}`,
+    },
+    {
+        title: 'MergeConsecutiveBlocks',
+        content: `// MergeConsecutiveBlocks pass
+// Merges basic blocks that are connected by
+// an unconditional branch.
+
+function mergeBlocks(fn) {
+  let changed = true;
+  while (changed) {
+    changed = tryMerge(fn.blocks);
+  }
+}`,
+    },
+    {
+        title: 'InlineImmediatelyInvokedFunctionExpressions',
+        content: `// InlineIIFE pass
+// Inlines immediately-invoked function
+// expressions (IIFEs) at their call site.
+
+function inlineIIFEs(fn) {
+  for (const instr of fn.body) {
+    if (isIIFE(instr)) inline(instr, fn);
+  }
+}`,
+    },
+    {
+        title: 'DropManualMemoization',
+        content: `// DropManualMemoization pass
+// Removes useMemo / useCallback wrappers that
+// the compiler can prove are unnecessary.
+
+function dropMemo(fn) {
+  for (const call of findMemoCalls(fn)) {
+    if (isSafeToRemove(call, fn)) remove(call);
+  }
+}`,
+    },
+    {
+        title: 'PruneMaybeThrows',
+        content: `// PruneMaybeThrows pass
+// Removes "maybe-throws" annotations from
+// instructions proven not to throw.
+
+function pruneThrows(fn) {
+  for (const instr of fn.body) {
+    if (instr.mayThrow && canProveNoThrow(instr)) {
+      instr.mayThrow = false;
+    }
+  }
+}`,
+    },
+    {
+        title: 'HIR',
+        content: `function MyApp
+MyApp(): <unknown> $9
+bb0 (block):
+  [1] <unknown> $0 = LoadGlobal import 'react'
+  [2] <unknown> $1 = 0
+  [3] <unknown> $2 = Call <unknown> $0(
+  [4] <unknown> $5 = Destructure Const
+  <unknown> setValue$4 ] = <unknown> $2
+  [5] <unknown> $6 = JSXText "Hello World"
+  [6] <unknown> $7 = JSX <div>{<unknown>
+  [7] Return Explicit <unknown> $7`,
+    },
+    {
+        title: 'EnvironmentConfig',
+        content: `// EnvironmentConfig
+{
+  "inferEffectDependencies": false,
+  "enableAssumeHooksFollowRulesOfReact": true,
+  "enableTransitivelyFreezeFunctionExpressions": true,
+  "validateRefAccessDuringRender": true,
+  "validateNoCapitalizedCalls": null,
+  "lowerContextAccess": null
+}`,
+    },
+    {
+        title: 'SourceMap',
+        content: `// SourceMap
+// Maps compiled output positions back to
+// original source positions.
+
+{
+  "version": 3,
+  "sources": ["MyApp.jsx"],
+  "mappings": "AAAA,SAAS,KAAK..."
+}`,
+    },
+];
+
+export function Collapsible() {
+    return (
+        <div className="flex flex-row min-h-screen overflow-x-auto border border-gray-300 font-mono">
+            {PANELS.map(({ title, content }) => (
+                <CollapsiblePanel key={title} title={title}>
+                    {content}
+                </CollapsiblePanel>
+            ))}
+        </div>
+    );
+}