diff --git a/desktop/index.html b/desktop/index.html
index 9034e1f..40be90c 100644
--- a/desktop/index.html
+++ b/desktop/index.html
@@ -26,15 +26,6 @@
           <label>Alias
             <input id="alias" type="text" placeholder="your name" />
           </label>
-          <label>Quality
-            <select id="quality">
-              <option value="auto">Auto</option>
-              <option value="good">Opus 24k</option>
-              <option value="degraded">Opus 6k</option>
-              <option value="codec2-3200">Codec2 3.2k</option>
-              <option value="catastrophic">Codec2 1.2k</option>
-            </select>
-          </label>
           <div class="form-row">
             <label class="checkbox">
               <input id="os-aec" type="checkbox" checked />
@@ -100,15 +91,20 @@
           </div>
           <div class="settings-section">
             <h3>Audio</h3>
-            <label>Quality
-              <select id="s-quality">
-                <option value="auto">Auto (adaptive)</option>
-                <option value="good">Good — Opus 24kbps</option>
-                <option value="degraded">Degraded — Opus 6kbps</option>
-                <option value="codec2-3200">Codec2 3200bps</option>
-                <option value="catastrophic">Catastrophic — Codec2 1200bps</option>
-              </select>
-            </label>
+            <div class="quality-control">
+              <div class="quality-header">
+                <span class="setting-label">QUALITY</span>
+                <span id="s-quality-label" class="quality-label">Auto</span>
+              </div>
+              <input id="s-quality" type="range" min="0" max="4" step="1" value="0" class="quality-slider" />
+              <div class="quality-ticks">
+                <span>Auto</span>
+                <span>Opus 24k</span>
+                <span>Opus 6k</span>
+                <span>C2 3.2k</span>
+                <span>C2 1.2k</span>
+              </div>
+            </div>
             <label class="checkbox">
               <input id="s-os-aec" type="checkbox" />
               OS Echo Cancellation (macOS VoiceProcessingIO)
diff --git a/desktop/src/main.ts b/desktop/src/main.ts
index 913ef28..9a73c85 100644
--- a/desktop/src/main.ts
+++ b/desktop/src/main.ts
@@ -8,7 +8,6 @@ const callScreen = document.getElementById("call-screen")!;
 const roomInput = document.getElementById("room") as HTMLInputElement;
 const aliasInput = document.getElementById("alias") as HTMLInputElement;
 const osAecCheckbox = document.getElementById("os-aec") as HTMLInputElement;
-const qualitySelect = document.getElementById("quality") as HTMLSelectElement;
 const connectBtn = document.getElementById("connect-btn") as HTMLButtonElement;
 const connectError = document.getElementById("connect-error")!;
 const roomName = document.getElementById("room-name")!;
@@ -49,7 +48,30 @@ const sRoom = document.getElementById("s-room") as HTMLInputElement;
 const sAlias = document.getElementById("s-alias") as HTMLInputElement;
 const sOsAec = document.getElementById("s-os-aec") as HTMLInputElement;
 const sAgc = document.getElementById("s-agc") as HTMLInputElement;
-const sQuality = document.getElementById("s-quality") as HTMLSelectElement;
+const sQuality = document.getElementById("s-quality") as HTMLInputElement;
+const sQualityLabel = document.getElementById("s-quality-label")!;
+
+// Quality slider config
+const QUALITY_STEPS = ["auto", "good", "degraded", "codec2-3200", "catastrophic"];
+const QUALITY_LABELS = ["Auto", "Opus 24k", "Opus 6k", "Codec2 3.2k", "Codec2 1.2k"];
+const QUALITY_COLORS = ["#4ade80", "#4ade80", "#facc15", "#e97320", "#991b1b"];
+
+function qualityToIndex(q: string): number {
+  const idx = QUALITY_STEPS.indexOf(q);
+  return idx >= 0 ? idx : 0;
+}
+
+function updateQualityUI(index: number) {
+  sQualityLabel.textContent = QUALITY_LABELS[index];
+  sQualityLabel.style.color = QUALITY_COLORS[index];
+  const pct = index / (QUALITY_STEPS.length - 1);
+  // Gradient: green at left → yellow middle → dark red at right
+  sQuality.style.background = `linear-gradient(90deg, #4ade80 0%, #facc15 40%, #e97320 70%, #991b1b 100%)`;
+}
+
+sQuality.addEventListener("input", () => {
+  updateQualityUI(parseInt(sQuality.value));
+});
 const sFingerprint = document.getElementById("s-fingerprint")!;
 const sRecentRooms = document.getElementById("s-recent-rooms")!;
 const sClearRecent = document.getElementById("s-clear-recent")!;
@@ -159,7 +181,6 @@ function applySettings() {
   roomInput.value = s.room;
   aliasInput.value = s.alias;
   osAecCheckbox.checked = s.osAec;
-  qualitySelect.value = s.quality || "auto";
   renderRecentRooms(s.recentRooms);
   renderRelayButton();
 }
@@ -380,7 +401,7 @@ async function doConnect() {
   userDisconnected = false;
 
   const s = loadSettings();
-  s.room = roomInput.value; s.alias = aliasInput.value; s.osAec = osAecCheckbox.checked; s.quality = qualitySelect.value;
+  s.room = roomInput.value; s.alias = aliasInput.value; s.osAec = osAecCheckbox.checked;
   const room = roomInput.value.trim();
   if (room) {
     const entry: RecentRoom = { relay: relay.address, room };
@@ -392,7 +413,7 @@ async function doConnect() {
     await invoke("connect", {
       relay: relay.address, room: roomInput.value,
       alias: aliasInput.value, osAec: osAecCheckbox.checked,
-      quality: qualitySelect.value,
+      quality: s.quality || "auto",
     });
     showCallScreen();
   } catch (e: any) {
@@ -534,7 +555,10 @@ listen("call-event", (event: any) => {
 // ── Settings ──
 function openSettings() {
   const s = loadSettings();
-  sRoom.value = s.room; sAlias.value = s.alias; sOsAec.checked = s.osAec; sQuality.value = s.quality || "auto";
+  sRoom.value = s.room; sAlias.value = s.alias; sOsAec.checked = s.osAec;
+  const qi = qualityToIndex(s.quality || "auto");
+  sQuality.value = String(qi);
+  updateQualityUI(qi);
   sFingerprint.textContent = myFingerprint || "(loading...)";
   renderSettingsRecentRooms(s.recentRooms);
   settingsPanel.classList.remove("hidden");
@@ -569,9 +593,10 @@ settingsPanel.addEventListener("click", (e) => { if (e.target === settingsPanel)
 
 settingsSave.addEventListener("click", () => {
   const s = loadSettings();
-  s.room = sRoom.value; s.alias = sAlias.value; s.osAec = sOsAec.checked; s.quality = sQuality.value;
+  s.room = sRoom.value; s.alias = sAlias.value; s.osAec = sOsAec.checked;
+  s.quality = QUALITY_STEPS[parseInt(sQuality.value)] || "auto";
   saveSettingsObj(s);
-  roomInput.value = s.room; aliasInput.value = s.alias; osAecCheckbox.checked = s.osAec; qualitySelect.value = s.quality;
+  roomInput.value = s.room; aliasInput.value = s.alias; osAecCheckbox.checked = s.osAec;
   renderRecentRooms(s.recentRooms);
   closeSettings();
 });
diff --git a/desktop/src/style.css b/desktop/src/style.css
index 9ddc6c2..02d3436 100644
--- a/desktop/src/style.css
+++ b/desktop/src/style.css
@@ -651,3 +651,90 @@ button.primary:disabled { opacity: 0.5; cursor: not-allowed; }
 }
 
 .secondary-btn:hover { border-color: var(--accent); color: var(--text); }
+
+/* ── Quality slider ── */
+.quality-control {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+  padding: 4px 0;
+}
+
+.quality-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.quality-label {
+  font-size: 13px;
+  font-weight: 600;
+  padding: 2px 8px;
+  border-radius: 6px;
+  transition: all 0.2s;
+}
+
+.quality-slider {
+  -webkit-appearance: none;
+  appearance: none;
+  width: 100%;
+  height: 6px;
+  border-radius: 3px;
+  outline: none;
+  cursor: pointer;
+  transition: background 0.2s;
+}
+
+.quality-slider::-webkit-slider-thumb {
+  -webkit-appearance: none;
+  appearance: none;
+  width: 18px;
+  height: 18px;
+  border-radius: 50%;
+  background: var(--text);
+  border: 2px solid var(--bg);
+  box-shadow: 0 1px 4px rgba(0,0,0,0.4);
+  cursor: pointer;
+  transition: transform 0.1s;
+}
+
+.quality-slider::-webkit-slider-thumb:hover {
+  transform: scale(1.15);
+}
+
+.quality-ticks {
+  display: flex;
+  justify-content: space-between;
+  font-size: 9px;
+  color: var(--text-dim);
+  padding: 0 2px;
+}
+
+.form select {
+  background: var(--surface);
+  border: 1px solid #333;
+  border-radius: 8px;
+  padding: 10px 12px;
+  color: var(--text);
+  font-size: 15px;
+  outline: none;
+  transition: border-color 0.2s;
+}
+
+.form select:focus {
+  border-color: var(--accent);
+}
+
+.settings-section select {
+  background: var(--surface);
+  border: 1px solid #333;
+  border-radius: 8px;
+  padding: 8px 10px;
+  color: var(--text);
+  font-size: 14px;
+  outline: none;
+}
+
+.settings-section select:focus {
+  border-color: var(--accent);
+}