fix(footer): tighten block-container `padding-bottom` to close white gap

Diagnostics confirmed the "white bar" the user has been describing is
not a separate element — it's ``[data-testid=stApp]``'s solid white
background (``rgb(255,255,255)``, viewport-locked) showing through the
gap between where page content ends and where the fixed Help/Close
footer overlay begins. ``stApp`` stays put while content scrolls
inside it, which is why the bar "doesn't change when scrolling".

The gap exists because ``render_sticky_footer`` overrides the block
container's ``padding-bottom`` to ``3rem`` (48px) to reserve clear
room for the fixed footer. The footer is only ~32-33px tall (min-
height 32px + 0.25rem top/bottom padding), so ~16px of that reserve
was pure visible white space sitting above the buttons.

Reduce ``padding-bottom`` to ``2rem`` (~32px) — just enough to
prevent content from rendering under the footer overlay, no more.
Eliminates the visible gap without exposing text to clipping.

Also remove the diagnostic banner + click-to-inspect iframe from
the home page now that the bar is identified.

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

src/gui/_home.py

@@ -288,163 +288,3 @@ def _home_page() -> None:
                         header=f"📄 {name}",
                         key_namespace=name,
                     )
-
-    # TEMP: end-of-content marker — confirmed at the true bottom of
-    # the home page's main content. The user reports content scrolls
-    # *behind* the offending white bar, so the bar is fixed-positioned.
-    # Only ``#datatools-sticky-footer`` is fixed at the bottom per
-    # our CSS, but the user already confirmed the sticky footer is
-    # NOT the offending bar. So there's a fixed element we haven't
-    # accounted for. The JS below outlines EVERY fixed/sticky element
-    # in the parent document with a labelled colored border so we can
-    # see exactly what's overlaying scrolled content.
-    st.markdown(
-        '<div style="background:#ffe0e0;border:2px dashed #b00020;'
-        'color:#b00020;font-weight:700;font-size:13px;text-align:center;'
-        'padding:8px 12px;margin:4px 0;font-family:system-ui,sans-serif;">'
-        '◀ CLAUDE TEST #3 — END OF MAIN CONTENT ▶'
-        '</div>',
-        unsafe_allow_html=True,
-    )
-    st.iframe(
-        """
-<script>
-(function () {
-  // CLICK-TO-INSPECT: a single button enters inspect mode. The next
-  // click anywhere on the page reports the full element stack at
-  // that point — including elements inside same-origin iframes
-  // (which earlier diagnostics couldn't reach with a flat walker).
-  // No clutter outside the button + the report panel; nothing
-  // re-runs on scroll.
-  function init() {
-    var doc = window.parent.document;
-    var winp = window.parent;
-    if (!doc || !doc.body) { setTimeout(init, 300); return; }
-    // Clear any earlier diagnostic chrome.
-    ['claude-diag-panel', 'claude-inspect-btn', 'claude-inspect-report']
-      .forEach(function (id) {
-        var prev = doc.getElementById(id);
-        if (prev) prev.remove();
-      });
-    doc.querySelectorAll('[data-claude-label]').forEach(function (n) {
-      n.remove();
-    });
-    doc.querySelectorAll('[data-claude-outlined]').forEach(function (el) {
-      el.style.outline = '';
-      el.style.outlineOffset = '';
-      el.removeAttribute('data-claude-outlined');
-    });
-
-    var btn = doc.createElement('button');
-    btn.id = 'claude-inspect-btn';
-    btn.type = 'button';
-    btn.textContent = 'CLAUDE: click here, then click the white bar';
-    btn.style.cssText =
-      'position:fixed;top:8px;right:8px;z-index:2147483647;'
-      + 'background:#b00020;color:#fff;font:13px/1.2 system-ui,sans-serif;'
-      + 'font-weight:700;padding:8px 14px;border:none;border-radius:6px;'
-      + 'cursor:pointer;box-shadow:0 4px 14px rgba(0,0,0,0.35);';
-    doc.body.appendChild(btn);
-
-    function describe(el) {
-      if (!el || !el.tagName) return '?';
-      var testid = el.getAttribute && el.getAttribute('data-testid');
-      var cls = (el.className && typeof el.className === 'string')
-        ? el.className.split(/\\s+/).slice(0, 3).join('.') : '';
-      var cs = (el.ownerDocument.defaultView || winp)
-        .getComputedStyle(el);
-      var rect = el.getBoundingClientRect();
-      return el.tagName.toLowerCase()
-        + (el.id ? '#' + el.id : '')
-        + (testid ? '[testid=' + testid + ']' : '')
-        + (cls ? '.' + cls : '')
-        + ' { pos=' + cs.position
-        + ', z=' + cs.zIndex
-        + ', bg=' + cs.backgroundColor
-        + ', rect=(' + Math.round(rect.left) + ','
-        + Math.round(rect.top) + ' '
-        + Math.round(rect.width) + 'x'
-        + Math.round(rect.height) + ') }';
-    }
-
-    function showReport(stack, x, y, frameLabel) {
-      var prev = doc.getElementById('claude-inspect-report');
-      if (prev) prev.remove();
-      var panel = doc.createElement('div');
-      panel.id = 'claude-inspect-report';
-      panel.style.cssText =
-        'position:fixed;top:8px;left:8px;right:8px;max-height:60vh;'
-        + 'overflow:auto;background:rgba(0,0,0,0.92);color:#fff;'
-        + 'font:12px/1.4 ui-monospace,monospace;padding:10px 12px;'
-        + 'border-radius:6px;z-index:2147483647;'
-        + 'box-shadow:0 4px 18px rgba(0,0,0,0.5);';
-      var html =
-        '<div style="font-weight:700;color:#ffb;margin-bottom:6px;">'
-        + 'CLICKED AT (' + x + ',' + y + ') — ' + frameLabel + '</div>';
-      stack.forEach(function (el, i) {
-        html += '<div style="margin:3px 0;padding:3px 6px;'
-          + 'background:' + (i === 0 ? '#3a0010' : '#111')
-          + ';border-left:3px solid '
-          + (i === 0 ? '#ff4060' : '#555') + ';">'
-          + (i === 0 ? '<b>TOP: </b>' : ('[' + i + '] '))
-          + describe(el) + '</div>';
-      });
-      html += '<button onclick="this.parentElement.remove()" '
-        + 'style="margin-top:8px;background:#444;color:#fff;'
-        + 'border:none;padding:4px 10px;border-radius:4px;'
-        + 'cursor:pointer;">close</button>';
-      panel.innerHTML = html;
-      doc.body.appendChild(panel);
-    }
-
-    function pickFromPoint(targetDoc, x, y, label, depth) {
-      depth = depth || 0;
-      var stack = (targetDoc.elementsFromPoint
-        ? targetDoc.elementsFromPoint(x, y) : []);
-      // Recurse into any same-origin iframe at the click point.
-      for (var i = 0; i < stack.length; i++) {
-        var el = stack[i];
-        if (el && el.tagName === 'IFRAME' && depth < 3) {
-          try {
-            var inner = el.contentDocument;
-            if (inner) {
-              var r = el.getBoundingClientRect();
-              var innerStack = pickFromPoint(inner,
-                x - r.left, y - r.top,
-                label + ' > IFRAME(' + (el.src || 'srcdoc') + ')',
-                depth + 1);
-              if (innerStack && innerStack.length) {
-                return innerStack.concat(stack);
-              }
-            }
-          } catch (e) { /* cross-origin */ }
-        }
-      }
-      // Tag the frame label onto the returned stack via showReport.
-      showReport(stack, x, y, label);
-      return stack;
-    }
-
-    btn.addEventListener('click', function (e) {
-      e.stopPropagation();
-      btn.textContent = 'click the white bar now…';
-      btn.style.background = '#0a8';
-      function onPick(ev) {
-        ev.preventDefault();
-        ev.stopPropagation();
-        doc.removeEventListener('click', onPick, true);
-        btn.textContent = 'CLAUDE: click here, then click the white bar';
-        btn.style.background = '#b00020';
-        pickFromPoint(doc, ev.clientX, ev.clientY, 'parent doc', 0);
-      }
-      setTimeout(function () {
-        doc.addEventListener('click', onPick, true);
-      }, 50);
-    });
-  }
-  init();
-})();
-</script>
-""",
-        height=1,
-    )

src/gui/components/_legacy.py

@@ -629,7 +629,12 @@ def render_sticky_footer() -> None:
         """
 <style>
 [data-testid="stAppViewBlockContainer"] {
-    padding-bottom: 3rem !important;
+    /* Reserve just enough room for the fixed footer overlay (min-height
+       32px + 0.25rem * 2 padding ≈ 2rem). Anything larger leaves a
+       visible white gap above the footer that the user sees as a
+       "white bar" between content and the Help/Close row — actually
+       just ``.stApp``'s solid-white background showing through. */
+    padding-bottom: 2rem !important;
 }
 #datatools-sticky-footer {
     position: fixed !important;