diff --git a/web/CarouselPicker.tsx b/web/CarouselPicker.tsx
index e5881d0..aca0075 100644
--- a/web/CarouselPicker.tsx
+++ b/web/CarouselPicker.tsx
@@ -70,7 +70,19 @@ export const CarouselPicker = ({
 
   return (
     <Dialog open={open} onOpenChange={(next) => !next && onClose()}>
-      <DialogContent className="sm:max-w-lg">
+      {/*
+        Bounded, and the list scrolls inside it.
+
+        `max-h-[80svh]` on the dialog and `min-h-0 overflow-y-auto` on the list. Both are needed: a
+        flex child will not shrink below its content without `min-h-0`, so the list pushes the dialog
+        taller than the screen and the overflow never engages — which is what happened here. There are
+        twenty-odd carousels now and the list ran off the bottom of the window with no way to reach the
+        end of it.
+
+        `svh` rather than `vh` because on a phone `vh` is the viewport with the browser chrome hidden,
+        so a dialog sized in it is taller than what you can actually see.
+      */}
+      <DialogContent className="flex max-h-[80svh] flex-col sm:max-w-lg">
         <DialogHeader>
           <DialogTitle>Choose a carousel</DialogTitle>
         </DialogHeader>
@@ -92,7 +104,7 @@ export const CarouselPicker = ({
           </p>
         )}
 
-        <div className="flex flex-col gap-1.5">
+        <div className="-mr-2 flex min-h-0 flex-1 flex-col gap-1.5 overflow-y-auto pr-2">
           {carousels?.map((carousel) => {
             const count = Array.isArray(carousel.items) ? carousel.items.length : 0;
             const current = carousel.id === selected;
diff --git a/web/sections/AddComponentDialog.tsx b/web/sections/AddComponentDialog.tsx
index 893c1e2..e2ae16a 100644
--- a/web/sections/AddComponentDialog.tsx
+++ b/web/sections/AddComponentDialog.tsx
@@ -132,12 +132,15 @@ export const AddComponentDialog = ({
   template?: boolean;
 }) => (
   <Dialog open={open} onOpenChange={(next) => !next && onCancel()}>
-    <DialogContent className="sm:max-w-lg">
+    {/* Bounded and scrolling, for the same reason CarouselPicker is: the list of kinds has grown to a
+        dozen and would otherwise run off a short screen with no way to reach the end. `min-h-0` on the
+        grid is what lets it shrink and the overflow engage. */}
+    <DialogContent className="flex max-h-[80svh] flex-col sm:max-w-lg">
       <DialogHeader>
         <DialogTitle>Add a component</DialogTitle>
       </DialogHeader>
 
-      <div className="grid grid-cols-2 gap-2">
+      <div className="-mr-2 grid min-h-0 flex-1 grid-cols-2 gap-2 overflow-y-auto pr-2">
         {/* `kind === null` is a choice that is not built yet — never a subject block, and it must not
             be filtered out by a list that only knows about the ones that are. */}
         {CHOICES.filter((choice) => template || choice.kind === null || !SUBJECT_KINDS.includes(choice.kind)).map(