diff --git a/src/components/DatePicker.tsx b/src/components/DatePicker.tsx
index 012aeeb..f96603d 100644
--- a/src/components/DatePicker.tsx
+++ b/src/components/DatePicker.tsx
@@ -12,7 +12,6 @@ import {
     type FocusEvent,
     type FocusEventHandler,
     type KeyboardEvent as ReactKeyboardEvent,
-    type MutableRefObject,
     type ReactNode,
     type Ref,
     useCallback,
@@ -143,7 +142,7 @@ function createDateTimeFromPickerValue(value: PickerValue): Date {
 }
 
 function startOfDay(value: Date): Date {
-    const candidate = new Date(value.getTime());
+    const candidate = new Date(value);
     candidate.setHours(0, 0, 0, 0);
     return candidate;
 }
@@ -256,7 +255,7 @@ function assignRef(ref: Ref<HTMLInputElement> | undefined, node: HTMLInputElemen
         return;
     }
 
-    (ref as MutableRefObject<HTMLInputElement | null>).current = node;
+    (ref as { current: HTMLInputElement | null }).current = node;
 }
 
 function tokenizeFormat(format: string): RawFormatPart[] {
@@ -616,7 +615,11 @@ function isWithinRange(
     return true;
 }
 
-function applySegmentDigits(baseValue: PickerValue, kind: SegmentKind, digits: string): PickerValue {
+function applySegmentDigits(
+    baseValue: PickerValue,
+    kind: SegmentKind,
+    digits: string,
+): PickerValue {
     const parsedDigits = Number(digits);
     if (!Number.isFinite(parsedDigits)) {
         return clonePickerValue(baseValue);
@@ -644,7 +647,8 @@ function applySegmentDigits(baseValue: PickerValue, kind: SegmentKind, digits: s
     const maxDayForCurrentMonth = daysInMonth(year, month);
     day = clampNumber(day, 1, maxDayForCurrentMonth);
 
-    const nextDate = createValidatedDate(year, month, day) ?? createDateAtLocalMidnight(year, month - 1, day);
+    const nextDate =
+        createValidatedDate(year, month, day) ?? createDateAtLocalMidnight(year, month - 1, day);
     return {
         date: nextDate,
         hour,
@@ -770,9 +774,11 @@ export function DatePicker({
     const inputWrapperRef = useRef<HTMLDivElement | null>(null);
     const popupRef = useRef<HTMLDivElement | null>(null);
     const changeHandledRef = useRef(false);
-    const bufferedDigitsRef = useRef<{ segmentIndex: number; digits: string; timestamp: number } | null>(
-        null,
-    );
+    const bufferedDigitsRef = useRef<{
+        segmentIndex: number;
+        digits: string;
+        timestamp: number;
+    } | null>(null);
     const activeSegmentIndexRef = useRef(0);
     const pendingSelectionTimerRef = useRef<number | null>(null);
 
@@ -897,7 +903,7 @@ export function DatePicker({
     const monthGrid = useMemo(() => buildMonthGrid(viewMonth, weekStart), [viewMonth, weekStart]);
 
     const recalculatePopupPosition = useCallback(() => {
-        if (!isOpen || !inputWrapperRef.current || !popupRef.current || typeof window === 'undefined') {
+        if (!isOpen || !inputWrapperRef.current || !popupRef.current || !globalThis.window) {
             return;
         }
 
@@ -920,7 +926,10 @@ export function DatePicker({
             ? anchorRect.top - popupRect.height - POPUP_GAP
             : anchorRect.bottom + POPUP_GAP;
 
-        top = Math.max(POPUP_MARGIN, Math.min(top, viewportHeight - POPUP_MARGIN - popupRect.height));
+        top = Math.max(
+            POPUP_MARGIN,
+            Math.min(top, viewportHeight - POPUP_MARGIN - popupRect.height),
+        );
 
         setPopupPosition({
             top,
@@ -937,7 +946,7 @@ export function DatePicker({
 
         recalculatePopupPosition();
 
-        if (typeof window === 'undefined') {
+        if (!globalThis.window) {
             return;
         }
 
@@ -965,7 +974,10 @@ export function DatePicker({
                 return;
             }
 
-            if (popupRef.current?.contains(eventTarget) || inputWrapperRef.current?.contains(eventTarget)) {
+            if (
+                popupRef.current?.contains(eventTarget) ||
+                inputWrapperRef.current?.contains(eventTarget)
+            ) {
                 return;
             }
 
@@ -992,7 +1004,7 @@ export function DatePicker({
     useEffect(() => {
         return () => {
             if (pendingSelectionTimerRef.current != null) {
-                window.clearTimeout(pendingSelectionTimerRef.current);
+                globalThis.window.clearTimeout(pendingSelectionTimerRef.current);
             }
         };
     }, []);
@@ -1007,15 +1019,15 @@ export function DatePicker({
             const clampedIndex = clampNumber(segmentIndex, 0, segments.length - 1);
             activeSegmentIndexRef.current = clampedIndex;
 
-            if (typeof window === 'undefined') {
+            if (!globalThis.window) {
                 return;
             }
 
             if (pendingSelectionTimerRef.current != null) {
-                window.clearTimeout(pendingSelectionTimerRef.current);
+                globalThis.window.clearTimeout(pendingSelectionTimerRef.current);
             }
 
-            pendingSelectionTimerRef.current = window.setTimeout(() => {
+            pendingSelectionTimerRef.current = globalThis.window.setTimeout(() => {
                 const inputNode = internalInputRef.current;
                 const targetSegment = segments[clampedIndex];
                 if (!inputNode || !targetSegment) {
@@ -1109,7 +1121,8 @@ export function DatePicker({
                 return;
             }
 
-            const baseValue = parsePickerValueWithFormat(displayValue, formatConfig) ?? clampedSelectedValue;
+            const baseValue =
+                parsePickerValueWithFormat(displayValue, formatConfig) ?? clampedSelectedValue;
             const nextUnclamped = applySegmentDigits(baseValue, segment.kind, digits);
             const nextClamped = clampPickerToRange(
                 nextUnclamped,
@@ -1145,7 +1158,7 @@ export function DatePicker({
         (segmentIndex: number, moveToNext: boolean) => {
             const buffered = bufferedDigitsRef.current;
             const segment = formatConfig.segments[segmentIndex];
-            if (!buffered || buffered.segmentIndex !== segmentIndex || !segment) {
+            if (buffered?.segmentIndex !== segmentIndex || !segment) {
                 if (moveToNext) {
                     selectSegment(segmentIndex + 1);
                 }
@@ -1234,7 +1247,12 @@ export function DatePicker({
                 hour: selectedHour,
                 minute: selectedMinute,
             };
-            const nextValue = clampPickerToRange(candidate, normalizedMinValue, normalizedMaxValue, type);
+            const nextValue = clampPickerToRange(
+                candidate,
+                normalizedMinValue,
+                normalizedMaxValue,
+                type,
+            );
             commitValue(formatPickerValueWithFormat(nextValue, formatConfig));
             setViewMonth(startOfMonth(normalizedDate));
         },
@@ -1341,7 +1359,12 @@ export function DatePicker({
                 return;
             }
 
-            const clamped = clampPickerToRange(parsed, normalizedMinValue, normalizedMaxValue, type);
+            const clamped = clampPickerToRange(
+                parsed,
+                normalizedMinValue,
+                normalizedMaxValue,
+                type,
+            );
             event.preventDefault();
             commitValue(formatPickerValueWithFormat(clamped, formatConfig));
         },
@@ -1663,7 +1686,11 @@ export function DatePicker({
                               <div className="datepicker-time-root">
                                   <div className="datepicker-time-column">
                                       <span className="datepicker-time-title">Hours</span>
-                                      <div className="datepicker-time-list" role="listbox" aria-label="Hours">
+                                      <div
+                                          className="datepicker-time-list"
+                                          role="listbox"
+                                          aria-label="Hours"
+                                      >
                                           {HOURS.map((hour) => {
                                               const hourDisabled = !isHourSelectableForRange(
                                                   selectedDate,
@@ -1717,7 +1744,8 @@ export function DatePicker({
                                                       type="button"
                                                       className={joinClassNames(
                                                           'datepicker-time-option',
-                                                          minute === selectedMinute && 'is-selected',
+                                                          minute === selectedMinute &&
+                                                              'is-selected',
                                                       )}
                                                       onClick={() => handleMinuteCommit(minute)}
                                                       disabled={minuteDisabled}