Bug 1618409 - Allow resizing on network table border. r=fvsch,Honza

Differential Revision: https://phabricator.services.mozilla.com/D73577

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

@@ -78,6 +78,11 @@
   table-layout: fixed;
 }
 
+.requests-list-table {
+  /* Clip column resizers when they are higher than the table. */
+  overflow: hidden;
+}
+
 .requests-list-column,
 .ws-frames-list-column {
   white-space: nowrap;
@@ -120,6 +125,11 @@
   border-bottom: 1px solid var(--theme-splitter-color);
 }
 
+.requests-list-headers th {
+  /* Allow column-resizers to be visible beyond the headers. */
+  overflow: visible;
+}
+
 .requests-list-headers th:not(:first-child),
 .ws-frames-list-headers th:not(:first-child) {
   border-inline-start: 1px solid var(--theme-splitter-color);
@@ -206,6 +216,9 @@
   min-height: 23px;
   position: absolute;
   background-color: transparent;
+  /* Extend column-resizers beyond table header to allow resizing on
+   * column borders as well.*/
+  height: 100vh;
 }
 
 /**