Show a compact year-less date in the day bar so it fits small iPhones

The native date input can't be told to drop the year, so a button face
shows e.g. "Jul 10" and the real input sits hidden behind it, still
holding the value and opening the native picker on tap.

src/style.css

@@ -147,10 +147,23 @@ body::before {
   flex-wrap: nowrap;
   padding: 8px 10px;
 }
-.day-bar input[type="date"] {
-  flex: 0 1 auto;
-  min-width: 0;
+/* The face button shows the short date; the real input sits invisibly behind
+   it so its native picker still anchors here (and .showPicker() has a target). */
+.day-date {
+  position: relative;
+  flex-shrink: 0;
+  display: inline-flex;
+}
+.day-date input[type="date"] {
+  position: absolute;
+  inset: 0;
+  width: 100%;
+  opacity: 0;
+  pointer-events: none;
+}
+#day-date-face {
   font-variant-numeric: tabular-nums;
+  white-space: nowrap;
 }
 .day-bar button {
   padding: 8px 10px;