refactor: remove dimmer overlay, add cyan border to preview popover

ANSI colors make the overlay content readable without dimming. Removed
preview-dimmer, liftHoveredTile(), tile--previewing/item--previewing —
all dead code now. Added var(--accent) 2px border to .preview-popover
for visual separation.

muxplex/frontend/app.js

@@ -127,7 +127,7 @@ let _notificationPermission = 'default';
 let _pollFailCount = 0;
 let _previewPopover = null;
 let _previewTimer = null;
-var _previewDimmer = null;
+
 var _previewSessionName = null;  // track by NAME, not DOM element
 
 // ─── DOM helpers ──────────────────────────────────────────────────────────────
@@ -465,8 +465,6 @@ function renderSidebar(sessions, currentSession) {
     });
   }
 
-  // Re-apply z-index lift after innerHTML rebuild (preview survives re-renders)
-  if (_previewSessionName) liftHoveredTile();
 }
 
 const SIDEBAR_KEY = 'muxplex.sidebarOpen';
@@ -606,8 +604,6 @@ function renderGrid(sessions) {
     updatePillBell();
   }
 
-  // Re-apply z-index lift after innerHTML rebuild (preview survives re-renders)
-  if (_previewSessionName) liftHoveredTile();
 }
 
 // ---------------------------------------------------------------------------
@@ -638,12 +634,6 @@ function showPreview(name) {
   hidePreviewDOM();
   _previewSessionName = name;
 
-  // Dimmer
-  var dimmer = document.createElement('div');
-  dimmer.className = 'preview-dimmer';
-  document.body.appendChild(dimmer);
-  _previewDimmer = dimmer;
-
   // Full-window overlay
   var popover = document.createElement('div');
   popover.className = 'preview-popover';
@@ -653,9 +643,6 @@ function showPreview(name) {
   document.body.appendChild(popover);
   _previewPopover = popover;
 
-  // Lift the original tile above dimmer
-  liftHoveredTile();
-
   // Auto-scroll to bottom (prompt area)
   popover.scrollTop = popover.scrollHeight;
 
@@ -663,22 +650,6 @@ function showPreview(name) {
   document.addEventListener('click', _previewClickHandler, true);
 }
 
-function liftHoveredTile() {
-  // Remove any existing lift class from all tiles/items
-  document.querySelectorAll('.tile--previewing, .item--previewing').forEach(function (el) {
-    el.classList.remove('tile--previewing', 'item--previewing');
-  });
-  if (!_previewSessionName) return;
-  var el = document.querySelector(
-    '.session-tile[data-session="' + _previewSessionName + '"]'
-  );
-  if (el) el.classList.add('tile--previewing');
-  var item = document.querySelector(
-    '.sidebar-item[data-session="' + _previewSessionName + '"]'
-  );
-  if (item) item.classList.add('item--previewing');
-}
-
 // hidePreviewDOM: removes the visual elements only (no render trigger)
 function hidePreviewDOM() {
   document.removeEventListener('click', _previewClickHandler, true);
@@ -686,13 +657,6 @@ function hidePreviewDOM() {
     _previewPopover.remove();
     _previewPopover = null;
   }
-  if (_previewDimmer) {
-    _previewDimmer.remove();
-    _previewDimmer = null;
-  }
-  document.querySelectorAll('.tile--previewing, .item--previewing').forEach(function (el) {
-    el.classList.remove('tile--previewing', 'item--previewing');
-  });
 }
 
 // hidePreview: full cleanup including timer and session name

muxplex/frontend/style.css

@@ -967,7 +967,7 @@ body {
   position: fixed;
   z-index: 500;
   background: var(--bg-secondary);
-  border: 1px solid var(--border);
+  border: 2px solid var(--accent);
   border-radius: 8px;
   padding: 16px 20px;
   /* Cover most of the viewport — centered with margin */
@@ -991,19 +991,7 @@ body {
   overflow-x: hidden;
 }
 
-.preview-dimmer {
-  position: fixed;
-  inset: 0;
-  z-index: 499;              /* behind popover (500), above everything else */
-  background: rgba(0, 0, 0, 0.55);
-  pointer-events: none;       /* clicks pass through — don't block mouseleave */
-}
 
-.session-tile.tile--previewing,
-.sidebar-item.item--previewing {
-  position: relative;
-  z-index: 500;               /* same as popover — above dimmer */
-}
 
 /* ============================================================
    Responsive overlay sidebar at <960px

muxplex/frontend/tests/test_app.mjs

@@ -2075,13 +2075,12 @@ test('hover preview popover works for both grid tiles and sidebar items', () =>
     'must handle sidebar items too');
 });
 
-test('hover preview popover has dim overlay and highlights hovered element', () => {
+test('hover preview popover uses cyan border and no dimmer', () => {
   const source = fs.readFileSync(
     new URL('../app.js', import.meta.url), 'utf8'
   );
-  assert.ok(source.includes('preview-dimmer'), 'must create dimmer overlay');
-  assert.ok(source.includes('tile--previewing'), 'must lift grid tile above dimmer');
-  assert.ok(source.includes('item--previewing'), 'must lift sidebar item above dimmer');
+  assert.ok(source.includes('preview-popover'), 'must create popover');
+  assert.ok(!source.includes('preview-dimmer'), 'must NOT use dimmer overlay (removed)');
 });
 
 test('hover preview delay is 1500ms (not 350ms)', () => {
@@ -2092,31 +2091,16 @@ test('hover preview delay is 1500ms (not 350ms)', () => {
   assert.ok(!source.includes(', 350)'), 'old 350ms delay must be removed');
 });
 
-test('hover preview uses full-window overlay with text wrapping', () => {
+test('hover preview uses full-window overlay with click-to-navigate', () => {
   const source = fs.readFileSync(
     new URL('../app.js', import.meta.url), 'utf8'
   );
   assert.ok(source.includes('_previewSessionName'), 'must track by session name');
-  assert.ok(source.includes('liftHoveredTile'), 'must re-lift tile after renders');
   assert.ok(source.includes('scrollHeight'), 'must auto-scroll to bottom');
-  assert.ok(source.includes('preview-dimmer'), 'must have dim overlay');
   assert.ok(source.includes('ontouchstart'), 'must be desktop-only');
   assert.ok(source.includes('_previewClickHandler'), 'must have click-to-navigate handler');
-  // Must NOT have repositionPreview (old side-positioned approach)
   assert.ok(!source.includes('repositionPreview'), 'must NOT have repositionPreview (old approach)');
-});
-
-test('renderGrid and renderSidebar re-lift hovered tile after innerHTML rebuild', () => {
-  const source = fs.readFileSync(
-    new URL('../app.js', import.meta.url), 'utf8'
-  );
-  // renderGrid should call liftHoveredTile after innerHTML
-  const gridFn = source.substring(source.indexOf('function renderGrid'), source.indexOf('function renderGrid') + 1500);
-  assert.ok(gridFn.includes('liftHoveredTile'), 'renderGrid must re-lift tile after render');
-
-  // renderGrid should NOT have the old _previewPopover guard
-  assert.ok(!gridFn.includes('if (_previewPopover) return'),
-    'renderGrid must NOT skip renders while preview active (old approach caused bugs)');
+  assert.ok(!source.includes('preview-dimmer'), 'must NOT have dimmer (removed — ANSI colors are readable without it)');
 });
 
 test('ansiToHtml converts SGR codes to styled spans', () => {

muxplex/tests/test_frontend_css.py

@@ -633,7 +633,10 @@ def test_preview_popover_css_exists():
     )
 
 
-def test_preview_dimmer_css_exists():
-    """Dim overlay behind popover must have CSS rules."""
+def test_preview_popover_has_accent_border():
+    """Preview popover must use brand cyan border."""
     css = read_css()
-    assert ".preview-dimmer" in css
+    start = css.index(".preview-popover {")
+    end = css.index("}", start)
+    block = css[start:end]
+    assert "var(--accent)" in block, ".preview-popover must use var(--accent) border"