test(home): broader diagnostic — outline anything near viewport bottom

Previous diagnostic only outlined fixed/sticky elements; user
confirmed the offending white bar isn't one of those. Cast a much
wider net:

- Outline every element whose visible rect intersects the bottom
  200px of the viewport, regardless of position.
- Border style encodes position: solid=fixed, dashed=sticky,
  dotted=absolute, thin=static/relative.
- Render a readable list in a top-right panel showing each element's
  tag/id/testid/class, position, z-index, height, and background.
- Skip fully transparent + un-positioned elements (those can't
  actually overlay anything).

With this, scroll to the bottom and the panel + colored outlines
will identify exactly which element is the white bar — fixed or
not. The user can paste the panel list (or just name the colored
box) so we know what to remove.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/gui/_home.py

@@ -310,11 +310,34 @@ def _home_page() -> None:
         """
 <script>
 (function () {
-  function outlineFixed() {
+  // Cast a wide net: outline EVERY element whose visible rect lives
+  // in the bottom 200px of the viewport, regardless of position type.
+  // Different border styles for different position values so the user
+  // can tell at a glance what kind of element each box is.
+  // Also dump a readable list onto the page (top-right panel) so the
+  // user can read the labels without needing devtools.
+  function styleFor(pos, idx) {
+    var palette = ['#e6194b', '#3cb44b', '#4363d8', '#f58231', '#911eb4',
+                   '#46f0f0', '#f032e6', '#bcf60c', '#fabebe', '#008080'];
+    var color = palette[idx % palette.length];
+    var width = '3px';
+    var style = 'solid';
+    if (pos === 'sticky') style = 'dashed';
+    else if (pos === 'absolute') style = 'dotted';
+    else if (pos === 'static' || pos === 'relative') {
+      style = 'solid';
+      width = '1px';
+    }
+    return { color: color, css: width + ' ' + style + ' ' + color };
+  }
+  function inspect() {
     var doc = window.parent.document;
     if (!doc) return;
-    // Clear previous outlines + labels so reruns don't stack.
-    doc.querySelectorAll('[data-claude-outline-label]').forEach(function (n) {
+    var winp = window.parent;
+    var vh = winp.innerHeight;
+    var vw = winp.innerWidth;
+    // Clear previous outlines + labels.
+    doc.querySelectorAll('[data-claude-label]').forEach(function (n) {
       n.remove();
     });
     doc.querySelectorAll('[data-claude-outlined]').forEach(function (el) {
@@ -322,51 +345,91 @@ def _home_page() -> None:
       el.style.outlineOffset = '';
       el.removeAttribute('data-claude-outlined');
     });
-    var palette = ['#e6194b', '#3cb44b', '#4363d8', '#f58231', '#911eb4',
-                   '#46f0f0', '#f032e6', '#bcf60c', '#fabebe', '#008080'];
+    var panel = doc.getElementById('claude-diag-panel');
+    if (panel) panel.remove();
+    panel = doc.createElement('div');
+    panel.id = 'claude-diag-panel';
+    panel.style.cssText =
+      'position:fixed;top:8px;right:8px;width:420px;max-height:60vh;'
+      + 'overflow:auto;background:rgba(0,0,0,0.88);color:#fff;'
+      + 'font:11px/1.35 ui-monospace,monospace;padding:8px 10px;'
+      + 'border-radius:6px;z-index:2147483647;'
+      + 'box-shadow:0 4px 16px rgba(0,0,0,0.4);';
+    panel.innerHTML =
+      '<div style="font-weight:700;margin-bottom:4px;">'
+      + 'CLAUDE DIAG — elements in bottom ' + 200 + 'px of viewport '
+      + '(vh=' + vh + ')</div>'
+      + '<div style="font-size:10px;opacity:.7;margin-bottom:6px;">'
+      + 'Border styles: solid=fixed, dashed=sticky, dotted=absolute, '
+      + 'thin=static/relative</div>';
+    var rows = [];
     var idx = 0;
-    doc.querySelectorAll('*').forEach(function (el) {
-      var cs = window.parent.getComputedStyle(el);
-      if (cs.position !== 'fixed' && cs.position !== 'sticky') return;
+    var seen = new Set();
+    doc.querySelectorAll('body *').forEach(function (el) {
+      if (seen.has(el)) return;
       var rect = el.getBoundingClientRect();
-      // Skip zero-size and off-screen-only items.
+      // Must intersect the bottom 200px of the viewport.
+      if (rect.bottom < vh - 200 || rect.top > vh) return;
       if (rect.width < 2 || rect.height < 2) return;
-      var color = palette[idx % palette.length];
+      if (rect.width > vw + 50 || rect.height > vh + 50) return;
+      var cs = winp.getComputedStyle(el);
+      // Skip transparent backgrounds — we want to find OPAQUE
+      // overlays. But keep fixed/sticky regardless, since those can
+      // still cause overlay even without bg color (children paint).
+      var hasOpaqueBg =
+        cs.backgroundColor !== 'rgba(0, 0, 0, 0)'
+        && cs.backgroundColor !== 'transparent';
+      var positioned = cs.position === 'fixed'
+        || cs.position === 'sticky' || cs.position === 'absolute';
+      if (!hasOpaqueBg && !positioned) return;
+      seen.add(el);
+      var st = styleFor(cs.position, idx);
       idx += 1;
-      el.style.outline = '3px solid ' + color;
+      el.style.outline = st.css;
       el.style.outlineOffset = '-3px';
       el.setAttribute('data-claude-outlined', '1');
-      // Label pinned to the element's top-left.
-      var label = doc.createElement('div');
-      label.setAttribute('data-claude-outline-label', '1');
+      var testid = el.getAttribute('data-testid');
       var name = el.tagName.toLowerCase()
         + (el.id ? '#' + el.id : '')
-        + (el.getAttribute('data-testid')
-              ? '[' + el.getAttribute('data-testid') + ']' : '')
-        + ' pos=' + cs.position
+        + (testid ? '[' + testid + ']' : '')
+        + (el.className && typeof el.className === 'string'
+              ? '.' + el.className.split(/\\s+/).slice(0, 2).join('.') : '');
+      var summary =
+        'pos=' + cs.position
+        + ' z=' + cs.zIndex
+        + ' top=' + Math.round(rect.top)
         + ' h=' + Math.round(rect.height) + 'px'
         + ' bg=' + cs.backgroundColor;
-      label.textContent = name;
-      label.style.cssText =
+      rows.push(
+        '<div style="margin:2px 0;padding:3px 5px;'
+        + 'border-left:4px solid ' + st.color + ';background:#111;">'
+        + '<div style="color:' + st.color + ';font-weight:700;">'
+        + name + '</div>'
+        + '<div style="opacity:.85;">' + summary + '</div></div>'
+      );
+      // Floating label on the element itself.
+      var lbl = doc.createElement('div');
+      lbl.setAttribute('data-claude-label', '1');
+      lbl.textContent = name;
+      lbl.style.cssText =
         'position:fixed;left:' + Math.max(0, rect.left) + 'px;'
-        + 'top:' + Math.max(0, rect.top - 18) + 'px;'
-        + 'background:' + color + ';color:#fff;'
-        + 'font:11px/1.2 ui-monospace,monospace;'
-        + 'padding:2px 5px;border-radius:3px;'
-        + 'z-index:2147483647;pointer-events:none;'
-        + 'white-space:nowrap;max-width:90vw;overflow:hidden;'
+        + 'top:' + Math.max(0, rect.top - 16) + 'px;'
+        + 'background:' + st.color + ';color:#fff;'
+        + 'font:10px/1.2 ui-monospace,monospace;'
+        + 'padding:1px 4px;border-radius:3px;'
+        + 'z-index:2147483646;pointer-events:none;'
+        + 'white-space:nowrap;max-width:60vw;overflow:hidden;'
         + 'text-overflow:ellipsis;';
-      doc.body.appendChild(label);
+      doc.body.appendChild(lbl);
     });
+    panel.innerHTML += rows.join('') || '<i>(nothing found)</i>';
+    doc.body.appendChild(panel);
   }
-  // Run after initial paint and again after Streamlit's component
-  // iframes settle.
-  setTimeout(outlineFixed, 400);
-  setTimeout(outlineFixed, 1500);
-  setTimeout(outlineFixed, 3500);
-  // Re-run on scroll so labels track the current viewport state.
+  setTimeout(inspect, 400);
+  setTimeout(inspect, 1500);
+  setTimeout(inspect, 3500);
   window.parent.addEventListener('scroll', function () {
-    setTimeout(outlineFixed, 50);
+    setTimeout(inspect, 80);
   }, true);
 })();
 </script>