diff --git a/web/src/lib/components/schema/SchemaDownload.svelte b/web/src/lib/components/schema/SchemaDownload.svelte
index ca7a444..19941bb 100644
--- a/web/src/lib/components/schema/SchemaDownload.svelte
+++ b/web/src/lib/components/schema/SchemaDownload.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
 	import RangeControl from "$lib/components/fields/schema/RangeControl.svelte";
 	import Icon from "$lib/components/ui/Icon.svelte";
-	import { onDismiss } from "$lib/components/ui/dismiss";
+	import { trackPopover } from "$lib/components/ui/popover-position";
 	import type { OutputMime } from "$lib/core/io";
 	import { OUTPUT_FORMATS, outputFormatByMime } from "$lib/output-formats";
 	import type { SliderSpec } from "$lib/registry-schema";
@@ -43,8 +43,16 @@
 			: undefined,
 	);
 
+	const menuId = $props.id();
 	let open = $state(false);
-	let root = $state<HTMLDivElement | null>(null);
+	let btn = $state<HTMLButtonElement | null>(null);
+	let menu = $state<HTMLDivElement | null>(null);
+
+	// While open, keep the popover placed next to the button (scroll/resize).
+	$effect(() => {
+		if (!open || !menu || !btn) return;
+		return trackPopover(menu, btn, "end");
+	});
 
 	function choose(mime: OutputMime) {
 		// Menu doubles as a format-settings panel: keep it open on select
@@ -56,23 +64,15 @@
 		const raw = (e.target as HTMLInputElement).valueAsNumber;
 		onlimit(Number.isFinite(raw) && raw >= 1 ? Math.round(raw) : undefined);
 	}
-
-	$effect(() => {
-		if (!open) return;
-		return onDismiss(
-			() => root,
-			() => (open = false),
-		);
-	});
 </script>
 
-<div class="download-split" bind:this={root}>
+<div class="download-split">
 	<button
 		type="button"
 		class="main"
 		disabled={running}
 		onclick={() => {
-			open = false;
+			menu?.hidePopover();
 			ondownload();
 		}}
 	>
@@ -80,66 +80,72 @@
 		<span>{t("actions.download")}</span>
 	</button>
 	<button
+		bind:this={btn}
 		type="button"
 		class="toggle"
 		aria-haspopup="menu"
 		aria-expanded={open}
+		aria-controls={menuId}
 		aria-label={t("actions.formatAria")}
 		disabled={running}
-		onclick={() => (open = !open)}
+		popovertarget={menuId}
 	>
 		<span>{current.label}</span>
 		<Icon icon={ChevronDown} size={14} />
 	</button>
-	{#if open}
-		<div class="menu" role="menu">
-			{#each OUTPUT_FORMATS as f (f.mime)}
-				<button
-					type="button"
-					class="item"
-					class:selected={f.mime === format}
-					role="menuitemradio"
-					aria-checked={f.mime === format}
-					onclick={() => choose(f.mime)}
-				>
-					{f.label}
-				</button>
-			{/each}
-			{#if qualitySpec && quality !== undefined}
-				<div class="quality">
-					<RangeControl
-						label={t("fields.quality")}
-						value={quality}
-						spec={qualitySpec}
-						onchange={(q) => onquality(q)}
-					/>
-				</div>
-			{/if}
-			<div class="limit">
-				<label class="limit-field">
-					<span>{t("actions.sizeLimitKb")}</span>
-					<input
-						type="number"
-						min="1"
-						step="1"
-						placeholder="∞"
-						value={limitKb ?? ""}
-						oninput={handleLimit}
-					/>
-				</label>
-				{#if limitKb !== undefined && format === "image/bmp"}
-					<p class="limit-warn" role="status">
-						{t("actions.sizeLimitBmp")}
-					</p>
-				{/if}
+	<div
+		bind:this={menu}
+		id={menuId}
+		class="menu"
+		role="menu"
+		popover="auto"
+		ontoggle={(e) => (open = e.newState === "open")}
+	>
+		{#each OUTPUT_FORMATS as f (f.mime)}
+			<button
+				type="button"
+				class="item"
+				class:selected={f.mime === format}
+				role="menuitemradio"
+				aria-checked={f.mime === format}
+				onclick={() => choose(f.mime)}
+			>
+				{f.label}
+			</button>
+		{/each}
+		{#if qualitySpec && quality !== undefined}
+			<div class="quality">
+				<RangeControl
+					label={t("fields.quality")}
+					value={quality}
+					spec={qualitySpec}
+					onchange={(q) => onquality(q)}
+				/>
 			</div>
+		{/if}
+		<div class="limit">
+			<label class="limit-field">
+				<span>{t("actions.sizeLimitKb")}</span>
+				<input
+					type="number"
+					min="1"
+					step="1"
+					placeholder="∞"
+					value={limitKb ?? ""}
+					oninput={handleLimit}
+				/>
+			</label>
+			{#if limitKb !== undefined && format === "image/bmp"}
+				<p class="limit-warn" role="status">
+					{t("actions.sizeLimitBmp")}
+				</p>
+			{/if}
 		</div>
-	{/if}
+	</div>
 </div>
 
 <style>
 	.download-split {
-		position: relative;
 		display: inline-flex;
 	}
 	.main,
@@ -171,19 +177,24 @@
 		cursor: not-allowed;
 	}
 	.menu {
-		position: absolute;
-		top: calc(100% + var(--space-s));
-		right: 0;
-		z-index: var(--z-dropdown);
+		/* Native popover: top layer + light dismiss + Escape из коробки;
+		   позиционирование — trackPopover (anchor() поддержан не везде). */
+		position: fixed;
+		margin: 0;
+		translate: 0 var(--space-s);
 		/* Ширина под строку качества: числовое поле + степперы + сброс. */
 		min-width: calc(var(--space-xxxl) * 9);
-		display: grid;
 		gap: var(--space-s);
 		padding: var(--space-m);
 		border: var(--size-border) solid var(--color-border);
 		border-radius: var(--radius-m);
 		background: var(--color-panel);
 	}
+	/* display задаётся только в открытом состоянии: авторский display
+	   перебивает UA-правило [popover]:not(:popover-open) { display: none }. */
+	.menu:popover-open {
+		display: grid;
+	}
 	.item {
 		padding: var(--space-m) var(--space-l);
 		border: var(--size-border) solid transparent;
diff --git a/web/src/lib/components/schema/ToolPickerButton.svelte b/web/src/lib/components/schema/ToolPickerButton.svelte
index 6e3048a..b8de73a 100644
--- a/web/src/lib/components/schema/ToolPickerButton.svelte
+++ b/web/src/lib/components/schema/ToolPickerButton.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
 	import Icon from "$lib/components/ui/Icon.svelte";
-	import { onDismiss } from "$lib/components/ui/dismiss";
+	import { trackPopover } from "$lib/components/ui/popover-position";
 	import { pageTitle } from "$lib/i18n/schema-tool-strings";
 	import { chainablePages } from "$lib/pipeline.svelte";
 	import type { Page } from "$lib/registry";
@@ -15,31 +15,33 @@
 
 	const pages = chainablePages();
 
+	const menuId = $props.id();
 	let open = $state(false);
-	let root = $state<HTMLDivElement | null>(null);
+	let btn = $state<HTMLButtonElement | null>(null);
+	let menu = $state<HTMLDivElement | null>(null);
+
+	// While open, keep the popover placed next to the button (scroll/resize).
+	$effect(() => {
+		if (!open || !menu || !btn) return;
+		return trackPopover(menu, btn, "end");
+	});
 
 	function choose(page: Page) {
 		onadd(page.steps[0].id);
-		open = false;
+		menu?.hidePopover();
 	}
-
-	$effect(() => {
-		if (!open) return;
-		return onDismiss(
-			() => root,
-			() => (open = false),
-		);
-	});
 </script>
 
-<div class="tool-picker" bind:this={root}>
+<div class="tool-picker">
 	<button
+		bind:this={btn}
 		type="button"
 		class={iconOnly ? "icon-btn" : "add-btn"}
 		aria-haspopup="menu"
 		aria-expanded={open}
+		aria-controls={menuId}
 		aria-label={iconOnly ? label : undefined}
-		onclick={() => (open = !open)}
+		popovertarget={menuId}
 	>
 		{#if iconOnly}
 			<Icon icon={Repeat} size={14} />
@@ -48,25 +50,29 @@
 			<span>{label}</span>
 		{/if}
 	</button>
-	{#if open}
-		<div class="menu" role="menu">
-			{#each pages as page (page.slug)}
-				<button
-					type="button"
-					class="item"
-					role="menuitem"
-					onclick={() => choose(page)}
-				>
-					{pageTitle(page)}
-				</button>
-			{/each}
-		</div>
-	{/if}
+	<div
+		bind:this={menu}
+		id={menuId}
+		class="menu"
+		role="menu"
+		popover="auto"
+		ontoggle={(e) => (open = e.newState === "open")}
+	>
+		{#each pages as page (page.slug)}
+			<button
+				type="button"
+				class="item"
+				role="menuitem"
+				onclick={() => choose(page)}
+			>
+				{pageTitle(page)}
+			</button>
+		{/each}
+	</div>
 </div>
 
 <style>
 	.tool-picker {
-		position: relative;
 		display: inline-flex;
 	}
 	.add-btn {
@@ -99,20 +105,25 @@
 		color: var(--color-text);
 	}
 	.menu {
-		position: absolute;
-		top: calc(100% + var(--space-s));
-		right: 0;
-		z-index: var(--z-dropdown);
+		/* Native popover: top layer + light dismiss + Escape из коробки;
+		   позиционирование — trackPopover (anchor() поддержан не везде). */
+		position: fixed;
+		margin: 0;
+		translate: 0 var(--space-s);
 		min-width: calc(var(--space-xxxl) * 8);
 		max-height: calc(var(--space-xxxl) * 8);
 		overflow-y: auto;
-		display: grid;
 		gap: var(--space-s);
 		padding: var(--space-m);
 		border: var(--size-border) solid var(--color-border);
 		border-radius: var(--radius-m);
 		background: var(--color-panel);
 	}
+	/* display задаётся только в открытом состоянии: авторский display
+	   перебивает UA-правило [popover]:not(:popover-open) { display: none }. */
+	.menu:popover-open {
+		display: grid;
+	}
 	.item {
 		padding: var(--space-m) var(--space-l);
 		border: var(--size-border) solid transparent;
diff --git a/web/src/lib/components/ui/DetailBadge.svelte b/web/src/lib/components/ui/DetailBadge.svelte
index f453f10..da272ea 100644
--- a/web/src/lib/components/ui/DetailBadge.svelte
+++ b/web/src/lib/components/ui/DetailBadge.svelte
@@ -1,9 +1,10 @@
 <script lang="ts">
 	import { t } from "$lib/i18n/t";
 	import Badge from "./Badge.svelte";
+	import { trackPopover } from "./popover-position";
 
 	interface Props {
-		tone: "warning" | "danger" | "info";
+		tone: "warning" | "danger";
 		label: string;
 		detail?: string;
 		role?: "alert" | "status";
@@ -11,19 +12,24 @@
 	let { tone, label, detail = undefined, role = "status" }: Props = $props();
 
 	const id = $props.id();
-	// Anchor name is per-instance: with a shared name several popovers would
-	// fight over the same anchor element.
-	let anchorName = `--badge-${id}`;
 	let open = $state(false);
+	let btn = $state<HTMLButtonElement | null>(null);
+	let popover = $state<HTMLSpanElement | null>(null);
+
+	// While open, keep the popover placed next to the "?" button.
+	$effect(() => {
+		if (!open || !popover || !btn) return;
+		return trackPopover(popover, btn, "start");
+	});
 </script>
 
 <span class="detail-badge">
 	<Badge {tone} {label} {role} />
 	{#if detail}
 		<button
+			bind:this={btn}
 			type="button"
 			class="more"
-			style:anchor-name={anchorName}
 			aria-label={t("ui.detailsAria")}
 			aria-expanded={open}
 			aria-controls={id}
@@ -32,12 +38,12 @@
 			?
 		</button>
 		<span
+			bind:this={popover}
 			{id}
 			class="popover"
 			role="tooltip"
 			popover="auto"
-			style:position-anchor={anchorName}
-			onbeforetoggle={(e) => (open = e.newState === "open")}
+			ontoggle={(e) => (open = e.newState === "open")}
 		>
 			{detail}
 		</span>
@@ -73,16 +79,17 @@
 		border-color: var(--color-main);
 	}
 	/* Нативный popover живёт в top layer: light dismiss, Escape и раскладка
-	   поверх всего — из коробки, без z-index и ручных подписок. */
+	   поверх всего — из коробки. Позиционирование — trackPopover: anchor()
+	   поддержан не во всех браузерах. */
 	.popover {
 		position: fixed;
 		margin: 0;
-		top: anchor(bottom);
-		left: anchor(left);
 		translate: 0 var(--space-s);
-		/* Не уезжает за правый край: доступная ширина считается от якоря. */
 		width: max-content;
-		max-width: calc(100vw - anchor(left) - var(--space-xl));
+		max-width: min(
+			calc(var(--space-xxxl) * 12),
+			calc(100vw - 2 * var(--space-xl))
+		);
 		padding: var(--space-m) var(--space-l);
 		border: var(--size-border-thick) solid var(--color-text-muted);
 		border-radius: var(--radius-m);
diff --git a/web/src/lib/components/ui/dismiss.ts b/web/src/lib/components/ui/dismiss.ts
deleted file mode 100644
index f27890f..0000000
--- a/web/src/lib/components/ui/dismiss.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-// Popover dismiss: close on pointerdown outside the root and on Escape.
-// Subscribe inside `$effect` while the popover is open; returns unsubscribe.
-export function onDismiss(
-	root: () => HTMLElement | null,
-	close: () => void,
-): () => void {
-	function onPointerDown(e: PointerEvent) {
-		if (!root()?.contains(e.target as Node)) close();
-	}
-	function onKey(e: KeyboardEvent) {
-		if (e.key === "Escape") close();
-	}
-	window.addEventListener("pointerdown", onPointerDown);
-	window.addEventListener("keydown", onKey);
-	return () => {
-		window.removeEventListener("pointerdown", onPointerDown);
-		window.removeEventListener("keydown", onKey);
-	};
-}
diff --git a/web/src/lib/components/ui/popover-position.ts b/web/src/lib/components/ui/popover-position.ts
new file mode 100644
index 0000000..432fde6
--- /dev/null
+++ b/web/src/lib/components/ui/popover-position.ts
@@ -0,0 +1,29 @@
+// Position a top-layer popover next to its anchor button. The Popover API
+// itself does not place the element; CSS anchor positioning is not available
+// in every browser, so placement is computed from the anchor rect and kept
+// in sync with scroll/resize while the popover stays open.
+export function trackPopover(
+	popover: HTMLElement,
+	anchor: HTMLElement,
+	align: "start" | "end" = "end",
+): () => void {
+	const place = () => {
+		const a = anchor.getBoundingClientRect();
+		// The UA stylesheet gives popovers inset: 0; without resetting it the
+		// over-constrained box (left: 0 vs our right) resolves to left: 0.
+		popover.style.inset = "auto";
+		popover.style.top = `${a.bottom}px`;
+		if (align === "end" || a.left + popover.offsetWidth > window.innerWidth) {
+			popover.style.right = `${window.innerWidth - a.right}px`;
+		} else {
+			popover.style.left = `${a.left}px`;
+		}
+	};
+	place();
+	window.addEventListener("scroll", place, true);
+	window.addEventListener("resize", place);
+	return () => {
+		window.removeEventListener("scroll", place, true);
+		window.removeEventListener("resize", place);
+	};
+}