Bug 1425839 Reduced requests-list-headers-wrapper z-index from 1000 to 1. r=rickychien

MozReview-Commit-ID: DwLsvluvNGm

--HG--
extra : rebase_source : a37ec22be895b1e0545eeb4f396f90f20e96d877

devtools/client/netmonitor/src/assets/styles/RequestList.css

@@ -100,7 +100,7 @@
 .requests-list-headers-wrapper {
   position: sticky;
   top: 0;
-  z-index: 1000;
+  z-index: 1;
   width: 100%;
   padding: 0;
 }