diff --git a/src/components/ChoiceSelect/ChoiceSelect.css b/src/components/ChoiceSelect/ChoiceSelect.css
index 33f38a7..cd2e8dc 100644
--- a/src/components/ChoiceSelect/ChoiceSelect.css
+++ b/src/components/ChoiceSelect/ChoiceSelect.css
@@ -118,3 +118,8 @@
   top: auto;
   bottom: calc(100% + var(--space-1));
 }
+
+.choice-select__listbox--portal {
+  position: fixed;
+  z-index: 1000; /* clear of any local stacking contexts in the panel */
+}
\ No newline at end of file
diff --git a/src/components/ChoiceSelect/ChoiceSelect.tsx b/src/components/ChoiceSelect/ChoiceSelect.tsx
index 6546a09..374ffea 100644
--- a/src/components/ChoiceSelect/ChoiceSelect.tsx
+++ b/src/components/ChoiceSelect/ChoiceSelect.tsx
@@ -1,5 +1,6 @@
 // ChoiceSelect.tsx
 import { useEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
 import { TriangleDownIcon } from '../../assets/icons/Triangle';
 import './ChoiceSelect.css';
 
@@ -15,6 +16,9 @@ type ChoiceSelectProps<T extends string> = {
 };
 
 const LISTBOX_MAX_HEIGHT = 240; // keep in sync with .choice-select__listbox max-height
+const LISTBOX_GAP = 4; // px, ~= var(--space-1)
+
+type Coords = { top: number; left: number; width: number; fontSize: number };
 
 function ChoiceSelect<T extends string>({
   value,
@@ -29,25 +33,49 @@ function ChoiceSelect<T extends string>({
   const [open, setOpen] = useState(false);
   const [highlight, setHighlight] = useState(0);
   const [dropUp, setDropUp] = useState(false);
+  const [coords, setCoords] = useState<Coords | null>(null);
 
   const rootRef = useRef<HTMLDivElement>(null);
   const triggerRef = useRef<HTMLButtonElement>(null);
+  const listboxRef = useRef<HTMLUListElement>(null);
+  const suppressNextClick = useRef(false);
 
-  useEffect(() => {
-    function handleClick(e: MouseEvent) {
-      if (rootRef.current && !rootRef.current.contains(e.target as Node)) {
-        setOpen(false);
-      }
+ useEffect(() => {
+  function handleMouseDown(e: MouseEvent) {
+    const target = e.target as Node;
+    const clickedOutside =
+      rootRef.current &&
+      !rootRef.current.contains(target) &&
+      !listboxRef.current?.contains(target);
+
+    if (clickedOutside && open) {
+      setOpen(false);
+      suppressNextClick.current = true;
     }
-    document.addEventListener('mousedown', handleClick);
-    return () => document.removeEventListener('mousedown', handleClick);
-  }, []);
+  }
 
-  // Re-check placement on scroll/resize while open, not just at open-time —
-  // the trigger's position can change (e.g. inside a scrollable panel).
+  function handleClickCapture(e: MouseEvent) {
+    if (suppressNextClick.current) {
+      e.preventDefault();
+      e.stopPropagation();
+      suppressNextClick.current = false;
+    }
+  }
+
+  document.addEventListener('mousedown', handleMouseDown);
+  document.addEventListener('click', handleClickCapture, true); // capture phase
+  return () => {
+    document.removeEventListener('mousedown', handleMouseDown);
+    document.removeEventListener('click', handleClickCapture, true);
+  };
+}, [open]);
+
+  // Re-check placement/position on scroll/resize while open — the trigger's
+  // position can change (e.g. inside a scrollable panel), and since the
+  // listbox is portaled it won't move with it automatically.
   useEffect(() => {
     if (!open) return;
-    const recalc = () => computeDropDirection();
+    const recalc = () => updatePlacement();
     window.addEventListener('scroll', recalc, true);
     window.addEventListener('resize', recalc);
     return () => {
@@ -64,23 +92,32 @@ function ChoiceSelect<T extends string>({
     onChange(options[nextIndex]);
   };
 
-  function computeDropDirection() {
-    const el = triggerRef.current;
-    if (!el) return;
+  function updatePlacement() {
+  const el = triggerRef.current;
+  if (!el) return;
 
-    const rect = el.getBoundingClientRect();
-    const spaceBelow = window.innerHeight - rect.bottom;
-    const spaceAbove = rect.top;
+  const rect = el.getBoundingClientRect();
+  const spaceBelow = window.innerHeight - rect.bottom;
+  const spaceAbove = rect.top;
+  const needsFlip = spaceBelow < LISTBOX_MAX_HEIGHT && spaceAbove > spaceBelow;
+  setDropUp(needsFlip);
 
-    // Prefer opening down. Only flip up if there's not enough room below
-    // AND there's more room above — otherwise stay down and let it scroll/clip.
-    const needsFlip = spaceBelow < LISTBOX_MAX_HEIGHT && spaceAbove > spaceBelow;
-    setDropUp(needsFlip);
-  }
+  // Capture the trigger's resolved font-size (its cqh has already resolved
+  // correctly here, since it's still inside the real container tree) and
+  // carry it as a plain px value into the portal, where cqh would break.
+  const fontSize = parseFloat(getComputedStyle(el).fontSize);
+
+  setCoords({
+    top: needsFlip ? rect.top - LISTBOX_GAP : rect.bottom + LISTBOX_GAP,
+    left: rect.left,
+    width: rect.width,
+    fontSize,
+  });
+}
 
   function openList() {
     if (disabled) return;
-    computeDropDirection();
+    updatePlacement();
     setOpen(true);
     const idx = options.indexOf(value);
     setHighlight(idx >= 0 ? idx : 0);
@@ -149,31 +186,47 @@ function ChoiceSelect<T extends string>({
         </span>
       </button>
 
-      {open && (
-        <ul
-          className={'choice-select__listbox' + (dropUp ? ' choice-select__listbox--up' : '')}
-          role="listbox"
-        >
-          {options.map((option, i) => (
-            <li
-              key={option}
-              role="option"
-              aria-selected={option === value}
-              className={
-                'choice-select__option' +
-                (option === value ? ' choice-select__option--selected' : '') +
-                (i === highlight ? ' choice-select__option--highlight' : '')
-              }
-              onMouseEnter={() => setHighlight(i)}
-              onClick={() => pick(option)}
-            >
-              {formatLabel(option)}
-            </li>
-          ))}
-        </ul>
-      )}
+      {open &&
+        coords &&
+        createPortal(
+          <ul
+            ref={listboxRef}
+            className={
+              'choice-select__listbox choice-select__listbox--portal' +
+              (dropUp ? ' choice-select__listbox--up' : '')
+            }
+            role="listbox"
+            style={{
+              fontSize: coords.fontSize,
+              left: coords.left,
+              width: coords.width,
+              // dropUp needs top: auto + bottom instead, see CSS note below
+              ...(dropUp
+                ? { top: 'auto', bottom: window.innerHeight - coords.top }
+                : { top: coords.top }),
+            }}
+          >
+            {options.map((option, i) => (
+              <li
+                key={option}
+                role="option"
+                aria-selected={option === value}
+                className={
+                  'choice-select__option' +
+                  (option === value ? ' choice-select__option--selected' : '') +
+                  (i === highlight ? ' choice-select__option--highlight' : '')
+                }
+                onMouseEnter={() => setHighlight(i)}
+                onClick={() => pick(option)}
+              >
+                {formatLabel(option)}
+              </li>
+            ))}
+          </ul>,
+          document.body
+        )}
     </div>
   );
 }
 
-export default ChoiceSelect;
+export default ChoiceSelect;
\ No newline at end of file
diff --git a/src/features/dsp408/components/InputSection/ChannelSection.css b/src/features/dsp408/components/ChannelSection/ChannelSection.css
similarity index 100%
rename from src/features/dsp408/components/InputSection/ChannelSection.css
rename to src/features/dsp408/components/ChannelSection/ChannelSection.css
diff --git a/src/features/dsp408/components/InputSection/ChannelSection.tsx b/src/features/dsp408/components/ChannelSection/ChannelSection.tsx
similarity index 100%
rename from src/features/dsp408/components/InputSection/ChannelSection.tsx
rename to src/features/dsp408/components/ChannelSection/ChannelSection.tsx
diff --git a/src/features/dsp408/components/DSP408Panel/DSP408Panel.tsx b/src/features/dsp408/components/DSP408Panel/DSP408Panel.tsx
index e3c7bfe..98bcd8d 100644
--- a/src/features/dsp408/components/DSP408Panel/DSP408Panel.tsx
+++ b/src/features/dsp408/components/DSP408Panel/DSP408Panel.tsx
@@ -11,7 +11,7 @@ import LoadingOverlay from '../../../../components/LoadingOverlay/LoadingOverlay
 import { InputChannel, OutputChannel } from '../../types';
 import MatrixSection from '../Matrixsection/Matrixsection';
 import GeqSection from '../GeqSection/GeqSection';
-import ChannelSection from '../InputSection/ChannelSection';
+import ChannelSection from '../ChannelSection/ChannelSection';
 import { DSP408Api } from '../../dsp408';
 import { DSP408 } from '../../../../types';
 import { SidebarId } from '../../constants';