diff --git a/web/ui/app.js b/web/ui/app.js
index 6124a6f..2e934d7 100644
--- a/web/ui/app.js
+++ b/web/ui/app.js
@@ -204,7 +204,6 @@ function renderSampleCards(samples) {
   return samples.map(s => `
     <div class="sample-card" data-action="play" data-wav="${esc(s.fullPath)}">
       <span class="sample-name" title="${esc(s.name)}">${esc(s.name)}</span>
-      <span class="sample-play-icon">▶</span>
     </div>
   `).join('');
 }
@@ -234,8 +233,8 @@ function renderLibraries(libs) {
     const sampleCount = Object.values(programs).reduce((sum, s) => sum + s.length, 0);
     return `
       <div class="library-card">
-        <div class="library-header">
-          <h3>${esc(cleanName(lib))}</h3>
+        <div class="library-header" onclick="this.parentNode.classList.toggle('collapsed')">
+          <h3>${esc(cleanName(lib))}<span class="lib-toggle">▾</span></h3>
           <span class="lib-meta">${progCount} programs · ${sampleCount} samples</span>
         </div>
         <div class="library-programs">
@@ -383,3 +382,17 @@ document.addEventListener('click', function(e) {
     playWav(btn.dataset.wav);
   }
 });
+
+// Section collapse toggle
+document.querySelectorAll('.section-toggle').forEach(h => {
+  h.addEventListener('click', function () {
+    this.classList.toggle('collapsed');
+    const target = document.getElementById(this.dataset.section);
+    target.style.display = target.style.display === 'none' ? '' : 'none';
+  });
+});
+
+// Collapse all libraries
+document.getElementById('wav-collapse-all').addEventListener('click', function () {
+  document.querySelectorAll('.library-card').forEach(c => c.classList.add('collapsed'));
+});
diff --git a/web/ui/index.html b/web/ui/index.html
index 889edb8..3f462e6 100644
--- a/web/ui/index.html
+++ b/web/ui/index.html
@@ -40,13 +40,17 @@
   </section>
 
   <section id="wav-section">
-    <h2>Sample Library</h2>
+    <h2 class="section-toggle" data-section="wav-body">Sample Library <span class="toggle-icon">▾</span></h2>
+    <div id="wav-body">
     <div class="wav-controls">
       <input type="text" id="wav-dir" placeholder="WAV directory" value="./output/wavs">
       <button id="wav-browse-btn">Browse</button>
     </div>
     <div id="wav-results" style="display:none">
-      <div id="wav-summary" class="wav-summary"></div>
+      <div class="wav-summary-row">
+        <div id="wav-summary" class="wav-summary"></div>
+        <button id="wav-collapse-all" class="collapse-all-btn">Collapse All</button>
+      </div>
       <div id="wav-player" class="wav-player" style="display:none">
         <div id="wav-now-playing" class="now-playing"></div>
         <div class="audio-bar">
@@ -56,6 +60,7 @@
       </div>
       <div id="wav-list" class="wav-library"></div>
     </div>
+    </div>
   </section>
 
   <section id="results-section">
diff --git a/web/ui/style.css b/web/ui/style.css
index 32aae1a..217dc61 100644
--- a/web/ui/style.css
+++ b/web/ui/style.css
@@ -50,6 +50,23 @@ section {
   margin-bottom: 20px;
 }
 
+/* Section collapse toggle */
+.section-toggle {
+  cursor: pointer;
+  user-select: none;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+.toggle-icon {
+  font-size: 12px;
+  transition: transform 0.2s;
+  display: inline-block;
+}
+.section-toggle.collapsed .toggle-icon {
+  transform: rotate(-90deg);
+}
+
 h2 {
   font-size: 16px;
   color: var(--text2);
@@ -298,52 +315,59 @@ h2 {
   border: 1px solid var(--bg3);
   border-radius: var(--radius);
   overflow: hidden;
+  margin-bottom: 8px;
 }
 
 .library-header {
-  padding: 14px 18px;
+  padding: 10px 16px;
   cursor: pointer;
   user-select: none;
   background: var(--bg);
-  border-bottom: 1px solid transparent;
+  border-bottom: 1px solid var(--bg3);
   transition: border-color 0.15s;
+  display: flex;
+  align-items: center;
+  gap: 12px;
 }
 .library-header:hover {
   border-color: var(--accent);
 }
 .library-header h3 {
-  font-size: 15px;
+  font-size: 14px;
   font-weight: 600;
   color: var(--text);
   margin: 0;
   text-transform: none;
   letter-spacing: 0;
+  display: flex;
+  align-items: center;
+  gap: 4px;
 }
 .library-header .lib-meta {
-  font-size: 12px;
+  font-size: 11px;
   color: var(--text2);
-  margin-top: 4px;
+  margin-left: auto;
 }
 
 .library-programs {
-  padding: 10px 18px 16px;
+  padding: 8px 16px 12px;
 }
 
 /* Program cards */
 .program-card {
-  margin-top: 14px;
+  margin-top: 10px;
 }
 .program-card:first-child {
   margin-top: 0;
 }
 
 .program-header {
-  cursor: pointer;
+  cursor: default;
   user-select: none;
-  margin-bottom: 8px;
+  margin-bottom: 6px;
 }
 .program-header h4 {
-  font-size: 13px;
+  font-size: 12px;
   font-weight: 600;
   color: var(--accent);
   margin: 0;
@@ -352,30 +376,28 @@ h2 {
   display: inline;
 }
 .program-header .prog-meta {
-  font-size: 11px;
+  font-size: 10px;
   color: var(--text2);
-  margin-left: 8px;
+  margin-left: 6px;
 }
 
 .program-samples {
   display: grid;
-  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
-  gap: 6px;
+  grid-template-columns: repeat(auto-fill, minmax(70px, 1fr));
+  gap: 4px;
 }
 
 /* Sample cards */
 .sample-card {
   background: var(--bg);
   border: 1px solid var(--bg3);
-  border-radius: var(--radius);
-  padding: 8px 10px;
+  border-radius: 4px;
+  padding: 4px 8px;
   cursor: pointer;
   display: flex;
-  flex-direction: column;
   align-items: center;
   justify-content: center;
-  gap: 4px;
-  min-height: 64px;
+  min-height: 28px;
   transition: border-color 0.15s, background 0.15s;
 }
 .sample-card:hover {
@@ -383,10 +405,10 @@ h2 {
 }
 .sample-card.playing {
   border-color: var(--green);
-  background: rgba(78, 204, 163, 0.1);
+  background: rgba(78, 204, 163, 0.15);
 }
 .sample-card .sample-name {
-  font-size: 11px;
+  font-size: 10px;
   color: var(--text);
   text-align: center;
   overflow: hidden;
@@ -395,7 +417,40 @@ h2 {
   max-width: 100%;
 }
 .sample-card .sample-play-icon {
-  font-size: 14px;
-  color: var(--accent2);
-  line-height: 1;
+  display: none;
+}
+
+/* Collapse all button */
+.wav-summary-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+}
+.collapse-all-btn {
+  background: var(--bg3);
+  color: var(--text2);
+  border: none;
+  border-radius: 4px;
+  padding: 4px 10px;
+  font-size: 11px;
+  cursor: pointer;
+  white-space: nowrap;
+}
+.collapse-all-btn:hover {
+  color: var(--text);
+}
+
+/* Library collapse state */
+.library-card.collapsed .library-programs {
+  display: none;
+}
+.library-header .lib-toggle {
+  font-size: 11px;
+  transition: transform 0.2s;
+  margin-left: 8px;
+  color: var(--text2);
+}
+.library-card.collapsed .lib-toggle {
+  transform: rotate(-90deg);
 }
\ No newline at end of file