Fix timezones

frontend/src/components/stats/SleepTimetable.tsx

@@ -1,6 +1,6 @@
 import { useMemo, useState, useEffect, Fragment } from 'react';
 import { useStats } from '../../hooks/useStats';
-import { timeToMinutes } from '../../utils/time';
+import { timeToMinutes, adjustForTimezone } from '../../utils/time';
 
 interface TimetableProps {
   from_date: string;
@@ -106,8 +106,8 @@ const Timetable = ({ from_date, to_date, day_start, day_end }: TimetableProps) =
     return timetable.slots.some((slot) => {
       if (slot.date !== date || !slot.sleeping) return false;
 
-      const sStart = timeToMinutes(slot.slot_start);
-      const sEnd = timeToMinutes(slot.slot_end);
+      const sStart = adjustForTimezone(timeToMinutes(slot.slot_start));
+      const sEnd = adjustForTimezone(timeToMinutes(slot.slot_end));
       
       if (sEnd <= sStart) {
         const overlap1 = Math.max(sStart, intervalStart) < Math.min(1440, intervalEnd);

frontend/src/utils/time.ts

@@ -68,7 +68,11 @@ export function formatElapsedTime(utcTimestamp: string): string {
  * @returns formatted datetime string
  */
 export function formatDateTime(date: Date | string): string {
-  const d = typeof date === 'string' ? new Date(date) : date;
+  let dateToParse = date;
+  if (typeof date === 'string' && !date.endsWith('Z') && !date.includes('+')) {
+    dateToParse = date + 'Z';
+  }
+  const d = typeof dateToParse === 'string' ? new Date(dateToParse) : dateToParse;
   return d.toLocaleString('sv-SE', {
     year: 'numeric',
     month: '2-digit',