Stop sticky header so nav no longer overlaps funds bar on scroll.

Transparent sticky header let scrolling stats text bleed through the nav labels.

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

frontend/src/styles/app.css

@@ -98,9 +98,9 @@ input {
   align-items: stretch;
   gap: 10px;
   padding: 14px 0 8px;
-  position: sticky;
-  top: 0;
-  z-index: 10;
+  /* 不 sticky：透明背景吸顶时会与下方资金条文字重叠 */
+  position: relative;
+  z-index: 1;
   background: transparent;
 }