diff --git a/components/tour/__tests__/tour.test.tsx b/components/tour/__tests__/tour.test.tsx
index 28a29759a..2c6d3412f 100644
--- a/components/tour/__tests__/tour.test.tsx
+++ b/components/tour/__tests__/tour.test.tsx
@@ -157,6 +157,24 @@ describe('tour targets', () => {
     }
   });
 
+  it('keeps the card off the target on a phone narrower than the card', () => {
+    const w = window.innerWidth;
+    const hgt = window.innerHeight;
+    Object.defineProperty(window, 'innerWidth', { configurable: true, value: 320 });
+    Object.defineProperty(window, 'innerHeight', { configurable: true, value: 568 });
+    try {
+      const fab = { top: 440, left: 247, width: 56, height: 56 };
+      // Measured off screen the card is at its full 360 px.
+      const pos = computeTooltipPosition(fab, 'right', { width: 360, height: 196 });
+      expect(pos.actualPlacement).toBe('top');
+      expect(pos.top + 196).toBeLessThanOrEqual(fab.top);
+      expect(pos.left).toBe(8);
+    } finally {
+      Object.defineProperty(window, 'innerWidth', { configurable: true, value: w });
+      Object.defineProperty(window, 'innerHeight', { configurable: true, value: hgt });
+    }
+  });
+
   it('leaves out on a phone the steps that point into the rail or the folder drawer', () => {
     const ids = (phone: boolean) =>
       getTourSteps({ isDemoMode: true, supportsCalendar: true, supportsWebDAV: true, touch: phone, phone }).map((s) => s.id);
diff --git a/components/tour/tour-overlay.tsx b/components/tour/tour-overlay.tsx
index 4c1594616..24b506e68 100644
--- a/components/tour/tour-overlay.tsx
+++ b/components/tour/tour-overlay.tsx
@@ -48,7 +48,8 @@ export function computeTooltipPosition(
 ): { top: number; left: number; actualPlacement: string } {
   const vw = window.innerWidth;
   const vh = window.innerHeight;
-  const tw = Math.max(tooltipSize.width, 200); // minimum fallback width
+  // minimum fallback width; never wider than the screen, measured off screen it can be
+  const tw = Math.min(Math.max(tooltipSize.width, 200), vw - 16);
   const th = Math.max(tooltipSize.height, 100); // minimum fallback height
 
   // Along the side it sits on, the card slides to stay on screen: above a
@@ -384,7 +385,8 @@ export function TourOverlay() {
         style={{
           top: tooltipPos?.top ?? -9999,
           left: tooltipPos?.left ?? -9999,
-          maxWidth: TOOLTIP_MAX_W,
+          // A margin of 8 on both sides, like the placement keeps.
+          maxWidth: `min(${TOOLTIP_MAX_W}px, calc(100vw - 16px))`,
           transition: reducedMotion ? "none" : "opacity 200ms ease, transform 200ms ease, top 300ms ease, left 300ms ease",
           pointerEvents: visible ? "auto" : "none",
         }}