refactor: clean up CSS styles and enhance JavaScript functionality

- Removed outdated CSS styles related to the calendar sticky behavior and duty item animations to streamline the stylesheet.
- Added a reflow trigger in the JavaScript function to ensure proper rendering of the day detail panel when opened, improving user experience.
- Enhanced overall code clarity by eliminating unnecessary styles and improving the animation handling logic.

webapp/js/dayDetail.js

@@ -186,6 +186,8 @@ function showAsBottomSheet() {
 
   requestAnimationFrame(() => {
     requestAnimationFrame(() => {
+      // Force reflow so WebView paints the "closed" state before we add --open
+      void panelEl.offsetHeight;
       overlayEl.classList.add("day-detail-overlay--visible");
       panelEl.classList.add("day-detail-panel--open");
       const closeBtn = panelEl.querySelector(".day-detail-close");

webapp/style.css

@@ -163,14 +163,6 @@ body {
   transition: box-shadow var(--transition-fast) ease-out;
 }
 
-.calendar-sticky.is-scrolled {
-  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
-}
-
-[data-theme="dark"] .calendar-sticky.is-scrolled {
-  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
-}
-
 /* === Calendar grid & day cells */
 .calendar {
   display: grid;
@@ -808,23 +800,6 @@ body.day-detail-sheet-open {
 .duty-item--current {
   border-left-color: var(--today);
   background: color-mix(in srgb, var(--today) 12%, var(--surface));
-  animation: duty-current-pulse 2s ease-in-out infinite;
-}
-
-@media (prefers-reduced-motion: reduce) {
-  .duty-item--current {
-    animation: none;
-  }
-}
-
-@keyframes duty-current-pulse {
-  0%,
-  100% {
-    box-shadow: 0 0 0 0 color-mix(in srgb, var(--today) 30%, transparent);
-  }
-  50% {
-    box-shadow: 0 0 0 4px color-mix(in srgb, var(--today) 15%, transparent);
-  }
 }
 
 /* === Loading / error / access denied */