diff --git a/public/i18n/de.json b/public/i18n/de.json
index af20826..ff1bb86 100644
--- a/public/i18n/de.json
+++ b/public/i18n/de.json
@@ -654,6 +654,8 @@
     "SAVE": "{{count}} Spiele hinzufügen",
     "SAVE_FAILED": "Der Import konnte nicht gespeichert werden.",
     "NEW": "Neuer Import",
+    "SELECT_ALL": "Alle auswählen",
+    "SELECT_NONE": "Alle abwählen",
     "LINE": "Zeile {{line}}",
     "SEARCH_FAILED": "Suche fehlgeschlagen",
     "SEARCH_AGAIN": "Neu suchen",
diff --git a/public/i18n/en.json b/public/i18n/en.json
index d584e90..527adff 100644
--- a/public/i18n/en.json
+++ b/public/i18n/en.json
@@ -654,6 +654,8 @@
     "SAVE": "Add {{count}} games",
     "SAVE_FAILED": "Could not save the import.",
     "NEW": "New import",
+    "SELECT_ALL": "Select all",
+    "SELECT_NONE": "Deselect all",
     "LINE": "Line {{line}}",
     "SEARCH_FAILED": "Search failed",
     "SEARCH_AGAIN": "Search again",
diff --git a/src/pages/ImportPage.jsx b/src/pages/ImportPage.jsx
index f35e717..693fb04 100644
--- a/src/pages/ImportPage.jsx
+++ b/src/pages/ImportPage.jsx
@@ -371,6 +371,12 @@ function Review({data, favorite, onSaved, onDone, expireSession}) {
         return {...choice, candidates, igdbId: candidate.igdbId,
             platform: preselectPlatform(data.rows[index].platform, candidate.platforms, favorite)};
     })), [data.rows, favorite]);
+    // A line without a match cannot be checked, one in the library only by hand; a hand check stays.
+    const checkAll = (checked) => setChoices((current) => current.map((choice) => {
+        const candidate = choice.candidates.find((known) => known.igdbId === choice.igdbId);
+        const next = checked && (choice.checked || (!!candidate && !candidate.inLibrary));
+        return choice.checked === next ? choice : {...choice, checked: next};
+    }));
     const chosen = choices.map((choice, index) => ({choice, row: data.rows[index]}))
         .filter(({choice}) => choice.checked && choice.igdbId && choice.platform.trim());
 
@@ -402,7 +408,9 @@ function Review({data, favorite, onSaved, onDone, expireSession}) {
         <Card className="gap-0 overflow-hidden p-0">
             <div className="flex flex-wrap items-center justify-between gap-3 border-b px-5 py-4">
                 <p className="text-sm text-muted-foreground">{t('IMPORT.REVIEW_HINT')}</p>
-                <div className="flex gap-2">
+                <div className="flex flex-wrap gap-2">
+                    <Button variant="outline" onClick={() => checkAll(true)} disabled={busy}>{t('IMPORT.SELECT_ALL')}</Button>
+                    <Button variant="outline" onClick={() => checkAll(false)} disabled={busy}>{t('IMPORT.SELECT_NONE')}</Button>
                     <Button variant="ghost" onClick={onDone} disabled={busy}>{t('IMPORT.NEW')}</Button>
                     <Button onClick={save} disabled={busy || chosen.length === 0}>
                         {busy && <Loader2 className="animate-spin"/>}{t('IMPORT.SAVE', {count: chosen.length})}
diff --git a/src/pages/ImportPage.test.jsx b/src/pages/ImportPage.test.jsx
index 56d449e..021a835 100644
--- a/src/pages/ImportPage.test.jsx
+++ b/src/pages/ImportPage.test.jsx
@@ -171,6 +171,32 @@ describe('ImportPage', () => {
         ]});
     });
 
+    it('checks every line with a new match at once, and none', async () => {
+        renderPage({'GET ': json(200, {imports: []}), 'GET /5': json(200, ready)}, '/import?id=5');
+        const checked = () => ['Hades', 'Celeste', 'Hade'].map((title) => screen.getByLabelText(`IMPORT.LINE: ${title}`).checked);
+        await screen.findByLabelText('IMPORT.LINE: Hades');
+
+        fireEvent.click(screen.getByRole('button', {name: 'IMPORT.SELECT_ALL'}));
+        // Celeste is in the library already.
+        expect(checked()).toEqual([true, false, true]);
+        expect(screen.getByRole('button', {name: 'IMPORT.SAVE:2'})).toBeTruthy();
+
+        fireEvent.click(screen.getByRole('button', {name: 'IMPORT.SELECT_NONE'}));
+        expect(checked()).toEqual([false, false, false]);
+        expect(screen.getByRole('button', {name: 'IMPORT.SAVE:0'}).disabled).toBe(true);
+    });
+
+    it('keeps a line in the library that was checked by hand on select all', async () => {
+        renderPage({'GET ': json(200, {imports: []}), 'GET /5': json(200, ready)}, '/import?id=5');
+        const celesteBox = await screen.findByLabelText('IMPORT.LINE: Celeste');
+        fireEvent.click(celesteBox);
+        expect(celesteBox.checked).toBe(true);
+
+        fireEvent.click(screen.getByRole('button', {name: 'IMPORT.SELECT_ALL'}));
+
+        expect(screen.getByLabelText('IMPORT.LINE: Celeste').checked).toBe(true);
+    });
+
     it('undoes a saved import after a confirm with the changed count', async () => {
         renderPage({
             'GET ': json(200, {imports: [{id: 4, source: 'CSV', status: 'SAVED', total: 3, matched: 3, createdAt: '2026-09-29T10:00:00Z'}]}),
diff --git a/src/style.css b/src/style.css
index c4d47c2..15a3029 100644
--- a/src/style.css
+++ b/src/style.css
@@ -222,6 +222,16 @@
     body {
         @apply bg-background text-foreground antialiased;
     }
+
+    /* The open list of a native select is drawn by the browser: without these it stays light in dark mode, with the
+       page's light text on it. */
+    .dark {
+        color-scheme: dark;
+    }
+
+    option {
+        @apply bg-popover text-popover-foreground;
+    }
 }
 
 /* Radix menus and selects lock the page scroll and add a right margin as wide as the scrollbar, measured as