Adopt shared WebUI structural primitives

webui/src/styles/calendar.css

@@ -895,13 +895,6 @@
   cursor: not-allowed;
 }
 
-.calendar-dialog-row,
-.calendar-dialog-date-row {
-  display: grid;
-  grid-template-columns: repeat(2, minmax(0, 1fr));
-  gap: 12px;
-}
-
 .calendar-dialog-name-color-row {
   display: grid;
   grid-template-columns: minmax(0, 1fr) 142px;
@@ -1117,13 +1110,6 @@
   font-weight: 700;
 }
 
-.calendar-outbox-toolbar {
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  gap: 12px;
-}
-
 .calendar-outbox-summary {
   display: flex;
   align-items: center;
@@ -1208,13 +1194,6 @@
   min-height: 240px;
 }
 
-.calendar-migration-heading {
-  display: flex;
-  align-items: center;
-  justify-content: space-between;
-  gap: 12px;
-}
-
 .calendar-migration-heading > div {
   display: grid;
   gap: 3px;
@@ -1504,8 +1483,6 @@
     max-width: none;
   }
 
-  .calendar-dialog-row,
-  .calendar-dialog-date-row,
   .calendar-dialog-name-color-row,
   .calendar-sync-status-panel dl {
     grid-template-columns: 1fr;