Fix calendar CSS for Firefox.

components/common/Calendar.module.css

@@ -3,11 +3,11 @@
   flex-direction: column;
   font-size: var(--font-size-small);
   flex: 1;
-  min-height: 285px;
+  min-height: 306px;
 }
 
 .calendar table {
-  flex: 1;
+  width: 100%;
   border-spacing: 5px;
 }
 
@@ -64,18 +64,34 @@
   font-size: var(--font-size-normal);
 }
 
+.body {
+  display: flex;
+}
+
 .selector {
   cursor: pointer;
 }
 
 .pager {
   display: flex;
+  flex: 1;
 }
 
 .pager button {
   align-self: center;
 }
 
+.middle {
+  flex: 1;
+}
+
+.left,
+.right {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+}
+
 .left svg {
   transform: rotate(90deg);
 }