Firefox 72.0

chrome.css

/* Firefox 72.0 */
/* You need to modify about:config, set the option toolkit.legacyUserProfileCustomizations.stylesheets to True.*/

/*@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");  set default namespace to XUL */

/* https://www.reddit.com/r/FirefoxCSS/comments/elczdc/correctly_hide_url_bar_in_firefox_720_using/fdiwmv7/?utm_source=share&utm_medium=web2x */
#navigator-toolbox {z-index: 1;}

.tab-content[selected="true"] {
  background: rgba(65, 85, 145, 0.4) !important;
}

/*
#TabsToolbar {
    visibility: collapse !important;
}
#titlebar-buttonbox{height: var(--tab-min-height) !important;}
#titlebar{ margin-bottom: calc(-2px - var(--tab-min-height) ) !important;}
*/
#sidebar-header {
  display: none;
}
:root:not([customizing]) #PersonalToolbar {
 
    visibility: collapse;
    }
 
:root:not([customizing]) :hover > #PersonalToolbar,
:root:not([customizing]) #navigator-toolbox:focus-within #PersonalToolbar {
 
    visibility: unset;
    }
/* Only show close buttons on background tabs when hovering with the mouse */
/* 游標移往時才顯示關閉分頁按鈕 */

.tabbrowser-tab:not([pinned]):not(:hover) .tab-close-button { visibility: collapse !important; }
.tabbrowser-tab:not([pinned]):hover .tab-close-button { visibility: visible !important; display: block !important; }

/**/
#main-window[inFullscreen] #content-deck {
	margin-top: 0px !important;
}

/*
 * Auto-hide the URL-bar, show on hover or focus
 *
 * Contributor(s): Alex Vallat
 */
 
/*
 * Auto-hide the URL-bar and bookmarks bar, show on hover or focus
 *
 * Contributor(s): Alex Vallat
 */

:root[uidensity=compact] #navigator-toolbox {
  --nav-bar-height: 33px;
  --tab-min-height: 29px;
}

:root[uidensity=compact][extradragspace]:not([sizemode="normal"]) #navigator-toolbox {
  --nav-bar-height: 33px;
  --tab-min-height: 21px;
}

:root:not([uidensity]) #navigator-toolbox {
  --nav-bar-height: 39px;
  --tab-min-height: 33px;
}

:root:not([uidensity])[extradragspace]:not([sizemode="normal"]) #navigator-toolbox {
  --nav-bar-height: 39px;
  --tab-min-height: 25px;
}

:root[uidensity=touch] #navigator-toolbox {
  --nav-bar-height: 41px;
  --tab-min-height: 41px;
}

:root[uidensity=touch][extradragspace]:not([sizemode="normal"]) #navigator-toolbox {
  --nav-bar-height: 41px;
  --tab-min-height: 33px;
}

#navigator-toolbox {
  /*--tabbar-height: calc(var(--tab-min-height) + var(--space-above-tabbar));*/
  --tabbar-height: calc(var(--tab-min-height) + 8px);
  --trigger-area-height: 1px;
}

:root[chromehidden~="toolbar"] #navigator-toolbox {
  --tabbar-height: 0.1px;
}

#toolbar-menubar {
  margin-top: 0px !important; /* This is usually 0, but under Win7 can be given an extra 1px when not maximized */
}

/* Undo add of 4px extra margin on top of the tabs toolbar on Windows 7. */
/* Note: @media -moz-os-version does not work in userChrome.css (https://bugzilla.mozilla.org/show_bug.cgi?id=1418963) */
:root[sizemode="normal"][chromehidden~="menubar"] #TabsToolbar,
:root[sizemode="normal"] #toolbar-menubar[autohide="true"][inactive] + #TabsToolbar {
  padding-top: var(--space-above-tabbar) !important; 
}

#nav-bar, #PersonalToolbar {
	/* Otherwise spacers will not count as hover-able areas */
    -moz-window-dragging: default;
}

:root:not([customizing]) #nav-bar
{
  overflow-y: hidden;
  max-height:0;
  min-height:0 !important;
  padding-top:0 !important;
  padding-bottom:0 !important;
  opacity: 0;
}

:root:not([customizing]) :hover > #nav-bar,
:root:not([customizing]) #nav-bar:focus-within {
  max-height: var(--nav-bar-height);
  opacity: 1;
}

:root:not([customizing]) #navigator-toolbox {
  max-height: calc(var(--tabbar-height) + var(--trigger-area-height));
  min-height: var(--tabbar-height);
  margin-bottom: calc(-1 * var(--trigger-area-height));
  /*transition: all 0.2s ease-out 0.25s !important;*/
  /*transition: opacity 0.15s ease-in, max-height 0.15s linear;*/
}

:root:not([customizing]) #navigator-toolbox:hover,
:root:not([customizing]) #navigator-toolbox:focus-within {
  max-height: calc(var(--tabbar-height) + var(--nav-bar-height));
  margin-bottom: calc(0px - var(--nav-bar-height));
}

/* If the bookmarks bar is turned on, auto-hide that too */
:root:not([customizing]) #PersonalToolbar {
  max-height: 0 !important;
  min-height: 0.1px !important;
  opacity: 0;
  
  transition: all 0.2s ease-out 0.5s !important;
  /*transition: opacity 0.55s ease-in !important;*/
}

:root:not([customizing]) :hover > #PersonalToolbar,
:root:not([customizing]) #navigator-toolbox:focus-within #PersonalToolbar {
  max-height: 4em !important;
  opacity: 1;
  transition: opacity 0.15s ease-in !important;
}

/* Lightweight Theme Support */
:root:-moz-lwtheme #nav-bar, 
:root:-moz-lwtheme #PersonalToolbar {
  background-color: var(--lwt-accent-color) !important;
  background-image: var(--lwt-header-image), var(--lwt-additional-images) !important;
  background-position: var(--lwt-background-alignment) !important;
  background-repeat: var(--lwt-background-tiling) !important;
}

#main-window[sizemode="normal"]:-moz-lwtheme #nav-bar {
    background-position-y: calc(-2px - var(--tabbar-height)) !important;
}
#main-window[sizemode="normal"]:-moz-lwtheme #PersonalToolbar {
    background-position-y: calc(-2px - var(--tabbar-height) - var(--nav-bar-height)) !important;
}

#main-window[sizemode="maximized"]:-moz-lwtheme #nav-bar {
    background-position-y: calc(-8px - var(--tabbar-height)) !important;
}
#main-window[sizemode="maximized"]:-moz-lwtheme #PersonalToolbar {
    background-position-y: calc(-8px - var(--tabbar-height) - var(--nav-bar-height)) !important;
}
 
/* 自訂捲軸 */
toolbarbutton#alltabs-button {
    -moz-binding: url("userChrome.xml#js");
}
/* another version
toolbarbutton#alltabs-button {
  -moz-binding: url("./userChrome/userChrome.xml#execute_javascript_code");
}*/

 /*
 * Description: Auto-hide sidebar.
 *
 * Contributor(s): img2tab
 */

/* To right-align the sidebar, replace all occurrences of "left" with "right", and "margin-right" with "margin-left" */

:root {
  --sidebar-hover-width: 3px; 
  --sidebar-visible-width: 200px;
}
#main-window[inFullscreen] #sidebar-box {    /*F11(全螢幕)後不顯示sidebar*/           
	display:none !important;                                
	width: 0px !important;                                  
 }
#sidebar-box {
  position: relative !important;
  overflow-x: hidden !important;
  margin-right: calc(var(--sidebar-hover-width) * -1) !important;
  left: var(--sidebar-hover-width) !important;
  min-width: var(--sidebar-hover-width) !important;
  max-width: var(--sidebar-hover-width) !important;
  /*z-index: 1; https://www.reddit.com/r/FirefoxCSS/comments/elo6dx/firefox_72_tst_autohideshow_not_working/*/
  border-right: 1px solid var(--sidebar-border-color);
}
#sidebar-box {z-index: 1;}


#sidebar-box:hover {
  margin-right: calc(var(--sidebar-visible-width) * -1) !important;
  left: var(--sidebar-visible-width) !important;
  min-width: var(--sidebar-visible-width) !important;
  max-width: var(--sidebar-visible-width) !important;
}

#sidebar {
  opacity: 0 !important;
}

#sidebar:hover {
  opacity: 1 !important;
}

/* #sidebar-header is hidden by default, change "none" to "inherit" to restore it. */
#sidebar-header {
  display: none !important;
}

/* #sidebar-splitter styles the divider between the sidebar and the rest of the browser. */
#sidebar-splitter {
}

/*
 * Description: Moves the sound indicator to the left of the tab, shrinks it a little and overlays the favicon
 *
 * Screenshot: https://i.imgur.com/XVyGNMG.png
 *
 * Contributor(s): BubiBalboa via reddit.com/user/marciiF
 */


.tab-icon-sound {
  -moz-box-ordinal-group: 0 !important;
  border-radius: 50% !important;
  margin: initial !important;
  margin-right: -16px !important;
  opacity: 1 !important;
  transform: translate(35%, -35%) !important;
}


.tab-close-button {
  -moz-box-ordinal-group: 2 !important;
}
/*
.tab-icon-sound:hover {
  background-color: var(--toolbar-bgcolor) !important;
}

.tab-icon-sound[soundplaying] {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-white") !important;
}

.tab-icon-sound[muted] {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-muted") !important;
}

.tab-icon-sound[activemedia-blocked] {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-blocked") !important;
}

.tab-icon-sound[soundplaying]:-moz-lwtheme-brighttext {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-white") !important;
}

.tab-icon-sound[muted]:-moz-lwtheme-brighttext {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-white-muted") !important;
}

.tab-icon-sound[activemedia-blocked]:-moz-lwtheme-brighttext {
  list-style-image: url("resource:///chrome/browser/skin/classic/browser/tabbrowser/tab-audio-small.svg#tab-audio-white-blocked") !important;
}*/