fix: Top20 dropdown floats above chart with fixed positioning

Co-authored-by: Cursor <cursoragent@cursor.com>

manual_trading_hub/static/chart.js

@@ -92,6 +92,8 @@
   const elVolRankMeta = document.getElementById("market-vol-rank-meta");
   const elVolRankList = document.getElementById("market-vol-rank-list");
   const elVolRankDetails = document.getElementById("market-vol-rank");
+  const elVolRankPanel =
+    elVolRankDetails && elVolRankDetails.querySelector(".market-vol-rank-panel");
   const elTf = document.getElementById("market-timeframe");
   const elRefresh = document.getElementById("market-refresh");
   const elStatus = document.getElementById("market-status");
@@ -2616,6 +2618,32 @@
     void postChartUnwatch();
   }
 
+  function positionVolRankPanel() {
+    if (!elVolRankDetails || !elVolRankPanel || !elVolRankDetails.open) return;
+    const summary = elVolRankDetails.querySelector("summary");
+    if (!summary) return;
+    const rect = summary.getBoundingClientRect();
+    const panelW = elVolRankPanel.offsetWidth || 300;
+    let left = rect.right - panelW;
+    left = Math.max(8, Math.min(left, window.innerWidth - panelW - 8));
+    const top = rect.bottom + 4;
+    const maxH = Math.min(420, window.innerHeight - top - 12);
+    elVolRankPanel.style.left = left + "px";
+    elVolRankPanel.style.top = top + "px";
+    elVolRankPanel.style.maxHeight = Math.max(180, maxH) + "px";
+  }
+
+  function bindVolRankPanel() {
+    if (!elVolRankDetails) return;
+    elVolRankDetails.addEventListener("toggle", function () {
+      if (elVolRankDetails.open) {
+        requestAnimationFrame(positionVolRankPanel);
+      }
+    });
+    window.addEventListener("resize", positionVolRankPanel);
+    window.addEventListener("scroll", positionVolRankPanel, true);
+  }
+
   function renderVolumeRank(data) {
     if (!elVolRankMeta || !elVolRankList) return;
     elVolRankList.innerHTML = "";
@@ -2674,6 +2702,9 @@
       li.appendChild(btn);
       elVolRankList.appendChild(li);
     });
+    if (elVolRankDetails && elVolRankDetails.open) {
+      requestAnimationFrame(positionVolRankPanel);
+    }
   }
 
   async function loadVolumeRank(forceRefresh) {
@@ -2830,6 +2861,7 @@
 
   function bind() {
     bindSlDrag();
+    bindVolRankPanel();
     if (elRefresh) {
       elRefresh.addEventListener("click", function () {
         loadChart(true);