diff --git a/frontend/src/calendar.css b/frontend/src/calendar.css
index 762e369..984bb0f 100644
--- a/frontend/src/calendar.css
+++ b/frontend/src/calendar.css
@@ -15,3 +15,6 @@
 .calendar-picker__grid.shift-prev{animation:calendar-month-prev 140ms ease-out}
 @keyframes calendar-month-next{from{opacity:0;transform:translateX(8px)}to{opacity:1;transform:none}}
 @keyframes calendar-month-prev{from{opacity:0;transform:translateX(-8px)}to{opacity:1;transform:none}}
+/* Desktop: center these modal sheets like list-editor/task-compose (default mask anchors top-left). */
+@media(min-width:931px){.app-sheet-mask:has(.calendar-sources-sheet),.app-sheet-mask:has(.calendar-subscription-form){place-items:center;padding:var(--space-24)}.app-sheet-mask:has(.calendar-sources-sheet) .calendar-sources-sheet,.app-sheet-mask:has(.calendar-subscription-form) .calendar-subscription-form{margin:0}}
+.calendar-source-add{min-height:44px}