diff --git a/assets/webui/index.html b/assets/webui/index.html
index 17861db..7216f39 100644
--- a/assets/webui/index.html
+++ b/assets/webui/index.html
@@ -50,29 +50,29 @@
 					<option value="600">600</option>
 				</select>
 				<button id="exportPageButton" class="button" type="button" data-short="单" title="导出单页" aria-label="导出单页" disabled>单页</button>
-				<button id="exportButton" class="button" type="button" data-short="多" title="导出文档" aria-label="导出文档" aria-haspopup="dialog" popovertarget="exportPanel" disabled>文档</button>
+				<button id="exportButton" class="button" type="button" data-short="多" title="导出文档" aria-label="导出文档" aria-haspopup="dialog" aria-controls="exportPanel" disabled>文档</button>
 			</div>
 		</header>
-		<div id="exportPanel" class="export-panel" popover role="dialog" aria-label="导出文档">
+		<dialog id="exportPanel" class="form-dialog" aria-label="导出文档">
 			<form id="exportForm">
-				<div class="export-row">
+				<div class="form-row">
 					<span id="exportScopeLabel">范围</span>
-					<div class="export-options" role="radiogroup" aria-labelledby="exportScopeLabel">
+					<div class="form-options" role="radiogroup" aria-labelledby="exportScopeLabel">
 						<label><input id="exportAll" type="radio" name="scope" value="all" checked autofocus><span>全部</span></label>
 						<label><input id="exportSpecified" type="radio" name="scope" value="specified"><span>指定</span></label>
 					</div>
 				</div>
-				<div id="exportRangeRow" class="export-row" hidden>
+				<div id="exportRangeRow" class="form-row" hidden>
 					<label for="exportRange">页码</label>
 					<input id="exportRange" type="text" aria-describedby="exportRangeStatus" autocomplete="off" spellcheck="false">
 				</div>
-				<div class="export-actions">
-					<div id="exportRangeStatus" class="export-range-status" role="status" aria-live="polite"></div>
-					<button class="button" type="button" popovertarget="exportPanel" popovertargetaction="hide">取消</button>
+				<div class="form-actions">
+					<div id="exportRangeStatus" class="form-status" role="status" aria-live="polite"></div>
+					<button id="exportCancel" class="button" type="button">取消</button>
 					<button id="exportSubmit" class="button" type="submit">导出</button>
 				</div>
 			</form>
-		</div>
+		</dialog>
 
 		<main class="workspace">
 			<aside class="page-list-panel">
diff --git a/assets/webui/ofdgo.css b/assets/webui/ofdgo.css
index 144a695..cc97363 100644
--- a/assets/webui/ofdgo.css
+++ b/assets/webui/ofdgo.css
@@ -256,15 +256,13 @@ button:not(:disabled):hover {
 	width: 54px;
 }
 
-.export-panel {
-	top: calc(var(--bar-height) + 8px);
-	right: 0;
-	bottom: auto;
-	left: auto;
-	width: var(--sidebar-width);
-	max-height: calc(100dvh - var(--bar-height) - 18px);
-	margin: 0;
-	padding: 12px;
+.form-dialog {
+	inset: 0;
+	width: 320px;
+	max-width: calc(100% - 24px);
+	max-height: calc(100dvh - 24px);
+	margin: auto;
+	padding: 0;
 	border: 1px solid var(--line);
 	background: var(--panel);
 	color: #1f2428;
@@ -272,7 +270,15 @@ button:not(:disabled):hover {
 	font-size: 14px;
 }
 
-.export-row {
+.form-dialog::backdrop {
+	background: rgb(31 36 40 / 18%);
+}
+
+.form-dialog > form {
+	padding: 12px;
+}
+
+.form-row {
 	display: grid;
 	grid-template-columns: 2em minmax(0, 1fr);
 	align-items: center;
@@ -280,22 +286,22 @@ button:not(:disabled):hover {
 	margin-bottom: 12px;
 }
 
-.export-options {
+.form-options {
 	display: flex;
 }
 
-.export-options label {
+.form-options label {
 	position: relative;
 	flex: 1;
 	cursor: pointer;
 }
 
-.export-options input {
+.form-options input {
 	position: absolute;
 	opacity: 0;
 }
 
-.export-options span {
+.form-options span {
 	display: flex;
 	align-items: center;
 	justify-content: center;
@@ -304,22 +310,22 @@ button:not(:disabled):hover {
 	background: #ffffff;
 }
 
-.export-options label + label span {
+.form-options label + label span {
 	border-left: 0;
 }
 
-.export-options input:checked + span {
+.form-options input:checked + span {
 	background: #e4f3ef;
 	color: var(--accent-strong);
 	box-shadow: 0 0 0 1px var(--accent) inset;
 }
 
-.export-options input:focus-visible + span {
+.form-options input:focus-visible + span {
 	outline: 2px solid var(--focus);
 	outline-offset: 2px;
 }
 
-.export-row input[type="text"] {
+.form-row input[type="text"] {
 	width: 100%;
 	min-width: 0;
 	height: var(--control-height);
@@ -330,11 +336,11 @@ button:not(:disabled):hover {
 	color: #1f2428;
 }
 
-.export-row input[aria-invalid="true"] {
+.form-row input[aria-invalid="true"] {
 	border-color: #b14343;
 }
 
-.export-range-status {
+.form-status {
 	min-width: 0;
 	color: var(--text-muted);
 	font-size: 12px;
@@ -342,20 +348,20 @@ button:not(:disabled):hover {
 	overflow-wrap: anywhere;
 }
 
-.export-actions {
+.form-actions {
 	display: grid;
 	grid-template-columns: minmax(0, 1fr) auto auto;
 	align-items: center;
 	gap: 8px;
 }
 
-#exportSubmit {
+.form-actions button[type="submit"] {
 	border-color: var(--accent);
 	background: var(--accent);
 	color: #ffffff;
 }
 
-#exportSubmit:not(:disabled):hover {
+.form-actions button[type="submit"]:not(:disabled):hover {
 	background: var(--accent-strong);
 }
 
@@ -794,7 +800,7 @@ button.outline-link:hover {
 .empty-state[hidden],
 .meta-list > [hidden],
 .navigation-tabs[hidden],
-.export-row[hidden],
+.form-row[hidden],
 .page-list[hidden],
 .page-frame[hidden],
 .progress-panel[hidden] {
@@ -1430,11 +1436,6 @@ button.outline-link:hover {
 		--sidebar-width: min(78vw, 292px);
 	}
 
-	.export-panel {
-		right: 10px;
-		width: min(300px, calc(100% - 20px));
-	}
-
 	.toolbar {
 		--tool-gap: 6px;
 	}
diff --git a/assets/webui/ofdgo.js b/assets/webui/ofdgo.js
index b71762d..0a5532a 100644
--- a/assets/webui/ofdgo.js
+++ b/assets/webui/ofdgo.js
@@ -67,6 +67,7 @@ const state = {
 	visibleThumbnails: new Set(),
 	exportFormats: [],
 	exportPages: null,
+	exportBackdrop: false,
 	showPages: !COMPACT_LAYOUT.matches,
 	showMeta: !COMPACT_LAYOUT.matches,
 };
@@ -105,6 +106,7 @@ const el = {
 	exportRangeRow: document.querySelector("#exportRangeRow"),
 	exportRange: document.querySelector("#exportRange"),
 	exportRangeStatus: document.querySelector("#exportRangeStatus"),
+	exportCancel: document.querySelector("#exportCancel"),
 	exportSubmit: document.querySelector("#exportSubmit"),
 	emptyState: document.querySelector("#emptyState"),
 	progressPanel: document.querySelector("#progressPanel"),
@@ -210,7 +212,16 @@ document.addEventListener("selectionchange", () => {
 });
 el.exportFormat.addEventListener("change", () => updateDPIControl());
 el.exportPageButton.addEventListener("click", () => exportFile(false));
-el.exportPanel.addEventListener("beforetoggle", prepareExportPanel);
+el.exportButton.addEventListener("click", openExportPanel);
+el.exportCancel.addEventListener("click", () => el.exportPanel.close());
+el.exportPanel.addEventListener("pointerdown", (event) => {
+	state.exportBackdrop = event.target === el.exportPanel;
+});
+el.exportPanel.addEventListener("click", (event) => {
+	if (state.exportBackdrop && event.target === el.exportPanel) {
+		el.exportPanel.close();
+	}
+});
 el.exportAll.addEventListener("change", updateExportRange);
 el.exportSpecified.addEventListener("change", () => {
 	updateExportRange();
@@ -275,7 +286,7 @@ updateSidebarState();
 boot();
 
 function handleKeyDown(event) {
-	if (event.defaultPrevented || event.isComposing || event.altKey || document.body.hasAttribute("aria-busy") || el.exportPanel.matches(":popover-open")) {
+	if (event.defaultPrevented || event.isComposing || event.altKey || document.body.hasAttribute("aria-busy") || el.exportPanel.open) {
 		return;
 	}
 	const key = event.key;
@@ -1508,16 +1519,13 @@ async function downloadAttachment(attachment) {
 	}
 }
 
-function prepareExportPanel(event) {
-	if (event.newState !== "open") {
-		return;
-	}
+function openExportPanel() {
 	if (!state.doc || document.body.hasAttribute("aria-busy")) {
-		event.preventDefault();
 		return;
 	}
 	el.exportForm.reset();
 	updateExportRange();
+	el.exportPanel.showModal();
 }
 
 async function updateExportRange() {
@@ -1532,7 +1540,7 @@ async function updateExportRange() {
 	if (!specified || !value) {
 		return;
 	}
-	const current = () => openSeq === state.openSeq && el.exportPanel.matches(":popover-open")
+	const current = () => openSeq === state.openSeq && el.exportPanel.open
 		&& el.exportSpecified.checked && value === el.exportRange.value.trim();
 	try {
 		const indices = await callWASM("ofdgoParsePageRange", value);
@@ -3322,9 +3330,7 @@ function setBusy(busy, text = "", percent = 0, status = "") {
 		}
 		return;
 	}
-	if (el.exportPanel.matches(":popover-open")) {
-		el.exportPanel.hidePopover();
-	}
+	el.exportPanel.close();
 	endPan();
 	el.progressPanel.hidden = false;
 	setProgress(text, percent, status);