src/components/CalendarView.vue

@@ -550,6 +550,21 @@ const handleHeaderYearChange = ({ scrollTop: st }) => {
 function openSettings() {
   settingsDialog.value?.open()
 }
+// Heuristic: rotate month label (180deg) only for predominantly Latin text.
+// We explicitly avoid locale detection; rely solely on characters present.
+// Disable rotation if any CJK Unified Ideograph or Compatibility Ideograph appears.
+function shouldRotateMonth(label) {
+  if (!label) return false
+  // Rotate ONLY if any Latin script alphabetic character is present.
+  // Prefer Unicode script property when supported.
+  try {
+    if (/\p{Script=Latin}/u.test(label)) return true
+  } catch (e) {
+    // Fallback for environments lacking Unicode property escapes.
+    if (/[A-Za-z\u00C0-\u024F\u1E00-\u1EFF]/u.test(label)) return true
+  }
+  return false
+}
 // Keep roughly same visible date when first_day setting changes.
 watch(
   () => calendarStore.config.first_day,
@@ -647,6 +662,7 @@ window.addEventListener('resize', () => {
             :key="`month-${week.virtualWeek}`"
             v-show="week.monthLabel"
             class="month-name-label"
+            :class="{ 'no-rotate': !shouldRotateMonth(week.monthLabel?.text) }"
             :style="{
               top: week.top + 'px',
               height: week.monthLabel?.height + 'px',
@@ -812,4 +828,8 @@ header h1 {
   transform: rotate(180deg);
   transform-origin: center;
 }
+
+.month-name-label.no-rotate > span {
+  transform: none;
+}
 </style>