diff --git a/README.md b/README.md
index d23d95a..7bdb551 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,4 @@
 # dotfiles
 
+## Notes
+1. create hard link from _firefox/userChrome.css_ to _.mozilla/firefox/\<profile>/chrome/userChrome.css
\ No newline at end of file
diff --git a/firefox/userChrome.css b/firefox/userChrome.css
new file mode 100644
index 0000000..dc5b0f6
--- /dev/null
+++ b/firefox/userChrome.css
@@ -0,0 +1,45 @@
+/* Hide main tabs toolbar */
+#main-window[tabsintitlebar="true"]:not([extradragspace="true"]) #TabsToolbar > .toolbar-items {
+    opacity: 0;
+    pointer-events: none;
+}
+#main-window:not([tabsintitlebar="true"]) #TabsToolbar {
+    visibility: collapse !important;
+}
+
+/* Sidebar min and max width removal */
+#sidebar {
+    max-width: none !important;
+    min-width: 0px !important;
+}
+/* Hide splitter, when using Tree Style Tab. */
+#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] + #sidebar-splitter {
+    display: none !important;
+}
+/* Hide sidebar header, when using Tree Style Tab. */
+#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] #sidebar-header {
+    visibility: collapse;
+}
+
+/* Shrink sidebar until hovered, when using Tree Style Tab. */
+:root {
+    --thin-tab-width: 30px;
+    --wide-tab-width: 200px;
+}
+#sidebar-box:not([sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"]) {
+    min-width: var(--wide-tab-width) !important;
+    max-width: none !important;
+}
+#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"] {
+    position: relative !important;
+    transition: all 100ms !important;
+    min-width: var(--thin-tab-width) !important;
+    max-width: var(--thin-tab-width) !important;
+}
+#sidebar-box[sidebarcommand="treestyletab_piro_sakura_ne_jp-sidebar-action"]:hover {
+    transition: all 200ms !important;
+    min-width: var(--wide-tab-width) !important;
+    max-width: var(--wide-tab-width) !important;
+    margin-right: calc((var(--wide-tab-width) - var(--thin-tab-width)) * -1) !important;
+    z-index: 1;
+}