diff -r 000000000000 -r 6474c204b198 browser/devtools/netmonitor/netmonitor.css
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/netmonitor/netmonitor.css	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,41 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#toolbar-labels {
+  overflow: hidden;
+}
+
+#details-pane-toggle[disabled] {
+  /* Don't use display: none; to avoid collapsing #requests-menu-toolbar */
+  visibility: hidden;
+}
+
+#custom-pane {
+  overflow: auto;
+}
+
+#response-content-image-box {
+  overflow: auto;
+}
+
+#timings-summary-blocked {
+  display: none; /* This doesn't work yet. */
+}
+
+#network-statistics-charts {
+  overflow: auto;
+}
+
+/* Responsive sidebar */
+@media (max-width: 700px) {
+  #toolbar-spacer,
+  #details-pane-toggle,
+  #details-pane[pane-collapsed],
+  .requests-menu-waterfall,
+  .requests-menu-footer-label,
+  .requests-menu-status-code {
+    display: none;
+  }
+}