mobile: fix edge beam (transform-rotate) + ONU master-detail layout

Edge glow: iOS Safari won't animate an @property-driven conic-gradient
angle, so the beam sat static / off the border on mobile. Reworked to the
robust technique: a .beam child masked to the border ring contains an
oversized conic-gradient ::before spun with transform: rotate 0→360deg; the
glow halo is a drop-shadow on the parent (survives the child mask). Works on
iOS/Safari; honors prefers-reduced-motion.

ONU info on narrow screens: was stacking the picker above the detail, so
selecting an ONU meant a long scroll to find it. Now master-detail — show
the picker OR the detail (not both), toggled by .show-detail on
#view-onu-info via a shared @media(max-width:860px) rule; selecting shows the
detail with a "← ONU list" back button, tab/sub-tab nav resets to the
picker. (Earlier commit already de-compacted the list: extra filters +
two-line rows.)

Docs: CLAUDE.md §15 (edge glow technique) + §17 (master-detail).

Verified offscreen at 414px: beam element present; panel-left/​panel-main
display toggles correctly on select/back; back button visible on mobile;
rendered both states.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -779,13 +779,15 @@ port of the iOS `Format.bps`.
 
 ### Animated edge glow
 
-`#edge-glow` is a fixed, pointer-events-none full-viewport element. A
+`#edge-glow` (fixed, pointer-events-none, full-viewport) holds a `.beam`
-`conic-gradient(from var(--beam-angle), …)` with a white-hot core is masked
+child masked to a 3px border ring (`mask` + `mask-composite: exclude`); the
-to just the 3px border ring (the standard `mask` + `mask-composite:
+ring contains a `::before` that is an oversized `conic-gradient` with a
-exclude` border trick) and animated by spinning the `@property
+white-hot core, spun with **`transform: rotate` 0→360°**, so the beam travels
---beam-angle` 0→360°, so a neon beam travels around the screen edge.
+around the screen edge. (It deliberately does *not* use an `@property`-
-Respects `prefers-reduced-motion`. z-index sits below the scanline overlay
+animated gradient angle — iOS Safari won't animate that, which left the beam
-(9999) and modals (10000).
+static on mobile.) The glow halo is a `drop-shadow` on the parent so it
+survives the child's mask. Respects `prefers-reduced-motion`; z-index sits
+below the scanline overlay (9999) and modals (10000).
 
 ---
 
@@ -874,7 +876,11 @@ deep-link here via `openOnuInfo`.
 The left list/search supports name/address/serial + equipment/version +
 PON-mode + status filters; rows are two-line (serial+status, then
 equipment · version · last-seen). Parent OLT and upstream switch are one
-combined card.
+combined card. On narrow screens it's **master-detail**: the picker and the
+detail don't stack (which buried the detail under a long list) — selecting an
+ONU swaps to the detail (`.show-detail` on `#view-onu-info`, via a
+`@media (max-width:860px)` rule in the shared CSS) with a "← ONU list" back
+button; navigating in via the tab/sub-tab resets to the picker.
 
 ### Single-ONU upgrade
 

renderer/app.css

@@ -416,39 +416,55 @@ button.danger:hover:not(:disabled) {
 .modal-type-label { display: block; }
 .modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 2px; }
 
-/* -------- Animated neon edge glow (beam travels around the border) -------- */
+/* -------- Animated neon edge glow (beam travels around the border) --------
-@property --beam-angle {
+   A rotating conic-gradient (transform: rotate — works on iOS Safari, unlike
-  syntax: "<angle>";
+   an @property-animated gradient angle) clipped to a thin border ring. The
-  initial-value: 0deg;
+   glow halo is a drop-shadow on the parent so it survives the child's mask. */
-  inherits: false;
-}
 #edge-glow {
   position: fixed;
   inset: 0;
   z-index: 9998;
   pointer-events: none;
+  filter: drop-shadow(0 0 6px var(--neon)) drop-shadow(0 0 16px var(--cyan));
+}
+#edge-glow .beam {
+  position: absolute;
+  inset: 0;
   padding: 3px;                 /* thickness of the glowing border band */
-  background: conic-gradient(
+  overflow: hidden;
-    from var(--beam-angle),
-    transparent 0deg,
-    transparent 38deg,
-    var(--cyan) 64deg,
-    #ffffff 90deg,
-    var(--neon) 116deg,
-    transparent 142deg,
-    transparent 360deg
-  );
   /* Keep only the padding ring (border band); punch out the interior. */
   -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
   -webkit-mask-composite: xor;
           mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
           mask-composite: exclude;
-  filter: drop-shadow(0 0 8px var(--neon)) drop-shadow(0 0 22px var(--cyan));
-  animation: beamspin 7s linear infinite;
 }
-@keyframes beamspin { to { --beam-angle: 360deg; } }
+#edge-glow .beam::before {
+  content: "";
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  width: 200vmax;               /* > viewport diagonal at any rotation */
+  height: 200vmax;
+  transform: translate(-50%, -50%);
+  background: conic-gradient(
+    from 0deg,
+    transparent 0deg,
+    transparent 40deg,
+    var(--cyan) 66deg,
+    #ffffff 90deg,
+    var(--neon) 114deg,
+    transparent 140deg,
+    transparent 360deg
+  );
+  animation: beamspin 7s linear infinite;
+  will-change: transform;
+}
+@keyframes beamspin {
+  from { transform: translate(-50%, -50%) rotate(0deg); }
+  to   { transform: translate(-50%, -50%) rotate(360deg); }
+}
 @media (prefers-reduced-motion: reduce) {
-  #edge-glow { animation: none; }
+  #edge-glow .beam::before { animation: none; }
 }
 
 /* -------- Top tabs -------- */
@@ -562,6 +578,19 @@ svg.spark { vertical-align: middle; opacity: 0.9; }
 .olt-modal { width: min(960px, 95vw); }
 .olt-modal-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 12px; }
 .olt-onu-list { max-height: 42vh; margin-top: 6px; }
+
+/* "Back to list" button only matters in the narrow master-detail layout. */
+.onu-detail-back { display: none; align-self: flex-start; }
+
+/* Narrow screens: the ONU info page is master-detail — show the picker OR
+   the selected ONU's detail, never both stacked (which buried the detail
+   under a long list). `.show-detail` is toggled in app.js on select / back. */
+@media (max-width: 860px) {
+  #view-onu-info .panel-main { display: none; }
+  #view-onu-info.show-detail .panel-left { display: none; }
+  #view-onu-info.show-detail .panel-main { display: flex; flex-direction: column; }
+  #view-onu-info .onu-detail-back { display: inline-block; }
+}
 .detail-card {
   background: var(--bg-elev);
   border: 1px solid var(--border);

renderer/app.js

@@ -261,6 +261,7 @@ for (const tab of $$('.tab')) {
     showView(view);
     // Dashboard loads itself on first visit; other tabs load on demand.
     if (view === '#view-dashboard' && !state.dashboard) loadDashboard();
+    if (view === '#view-onu-info') $('#view-onu-info').classList.remove('show-detail');
   });
 }
 
@@ -1857,10 +1858,22 @@ for (const st of $$('.subtab')) {
   st.addEventListener('click', () => {
     const view = st.dataset.subview;
     showView(view);
-    if (view === '#view-onu-info' && state.fleet.length) renderOnuInfoList();
+    if (view === '#view-onu-info') {
+      $('#view-onu-info').classList.remove('show-detail'); // land on the picker
+      if (state.fleet.length) renderOnuInfoList();
+    }
   });
 }
 
+// "Back to list" in the narrow master-detail layout (delegated — the detail
+// re-renders several times).
+$('#onu-info-detail').addEventListener('click', (e) => {
+  if (e.target.closest('.onu-detail-back')) {
+    e.preventDefault();
+    $('#view-onu-info').classList.remove('show-detail');
+  }
+});
+
 // -------- ONU info / stats page --------
 
 $('#onu-info-load').addEventListener('click', async () => {
@@ -1937,6 +1950,8 @@ function renderOnuInfoList() {
 
 function selectOnuInfo(onuId) {
   state.onuInfoSelected = onuId;
+  // Narrow layout: switch from the picker to the detail (master-detail).
+  $('#view-onu-info').classList.add('show-detail');
   for (const row of $$('#onu-info-list .onu-info-row')) {
     row.classList.toggle('selected', row.dataset.id === onuId);
   }
@@ -1994,7 +2009,7 @@ async function renderOnuDetail(onuId) {
   const cfg = state.fleet.find((c) => c._id === onuId);
   if (!cfg) { el.innerHTML = '<p class="muted">ONU not found in the loaded fleet — reload the fleet.</p>'; return; }
 
-  const head = `<h2>${escapeHtml(cfg._id)}</h2>`;
+  const head = `<button class="ghost onu-detail-back" type="button">← ONU list</button><h2>${escapeHtml(cfg._id)}</h2>`;
   // Identity + link render instantly from the loaded fleet; the rest streams
   // in from one getOnuDetail call.
   el.innerHTML = `${head}<div class="detail-grid">

renderer/index.html

@@ -7,7 +7,7 @@
 </head>
 <body>
   <!-- Animated neon beam that travels around the screen edge. -->
-  <div id="edge-glow" aria-hidden="true"></div>
+  <div id="edge-glow" aria-hidden="true"><div class="beam"></div></div>
 
   <header class="topbar">
     <div class="brand">PON Fleet Upgrader</div>