fix: Top20 dropdown floats above chart with fixed positioning

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

manual_trading_hub/static/app.css

@@ -2628,6 +2628,9 @@ body.login-page {
   flex-wrap: wrap;
   gap: 10px;
   align-items: flex-end;
+  position: relative;
+  z-index: 60;
+  overflow: visible;
 }
 
 .market-field {
@@ -2928,11 +2931,16 @@ body.login-page {
   pointer-events: auto;
 }
 
+.market-field-symbol {
+  overflow: visible;
+}
+
 .market-field-symbol .market-symbol-wrap {
   display: flex;
   align-items: stretch;
   gap: 6px;
   min-width: 0;
+  overflow: visible;
 }
 
 .market-field-symbol .market-symbol-wrap > input {
@@ -2943,6 +2951,11 @@ body.login-page {
 .market-vol-rank {
   position: relative;
   flex: 0 0 auto;
+  overflow: visible;
+}
+
+.market-toolbar:has(.market-vol-rank[open]) {
+  z-index: 1300;
 }
 
 .market-vol-rank > summary {
@@ -2972,17 +2985,15 @@ body.login-page {
 }
 
 .market-vol-rank-panel {
-  position: absolute;
-  top: calc(100% + 4px);
-  right: 0;
-  z-index: 30;
+  position: fixed;
+  z-index: 1310;
   width: min(320px, 72vw);
-  max-height: 360px;
+  max-height: min(420px, 70vh);
   overflow: auto;
   border: 1px solid var(--border-soft);
   border-radius: 8px;
   background: var(--panel-bg, #1a1f2e);
-  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.4);
+  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.55);
   padding: 8px 0 6px;
 }