userChrome.css

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

/* Hide tab borders */
:root {
    --tabs-border: transparent !important;
}

/* Hide separators between background tabs */
.tabbrowser-tab::before {
    color: purple !important; 
    opacity: 0 !important; 
}

/* Hide border from rightmost background tab */
.tabbrowser-tab::after {
    color: green !important; 
    opacity: 0 !important; 
  }

/* Remove placeholder right border */
.titlebar-placeholder {
    border: none !important;
}

/* Url bar dropdown list */
#PopupAutoCompleteRichResult{
    margin-top: -3px !important;
}

#PopupAutoCompleteRichResult > richlistbox {
    -moz-box-orient: horizontal;
    overflow: hidden;
    background-color: #0c0c0d !important;
}

.ac-url-text, .ac-action-text {
    color: #e6e6e6 !important;
}

#PopupAutoCompleteRichResult > richlistbox > richlistitem > hbox > description > description:not(.ac-url-text) {
    color: #33ff66 !important;
}

#PopupAutoCompleteRichResult > richlistbox > richlistitem[selected] {
        background-color: #0a335c !important;
}

/* Page loading throbber on tabs */
.tab-throbber::before {
    fill: #33ff66 !important;
    opacity: 1 !important;
}

/* Hide SSL identity label */
#identity-icon-labels{
    display: none !important;
}

/* Hide favicon in tabs */
.tab-icon-image{
    display:none !important;
}

/* Change color of selected tab text */
#TabsToolbar .tabbrowser-tab[selected] {
    color: #33ff66 !important;
}

/* Change Color of all tabs */  
.tab-background {
    background-attachment: none!important;
    background-color: #0c0c0d!important;
    background-image: none!important;
}

/* Reduce width of pinned tabs by reducing the left and right padding */
 #TabsToolbar .tab-content[pinned] {
    padding:    0 9px !important;
}
 
/* Move tabs over to right to make room for address bar */
 #TabsToolbar {
    margin:         0 0 0 43vw !important;
    height:         31px !important;
    padding-left:   -5px !important;
    background: #0c0c0d !important;
}
 
/* Move address bar to titlebar with tabs */
 #nav-bar {
    margin:         -30px 57vw -1px 69px !important;
    height:         31px !important;
    border-bottom:  none !important;
    background: #0c0c0d !important;
}
 
/* URL bar width adjustments */
#urlbar-container {
    border:         none !important;
    width: 100px !important;
}

#urlbar {
    background:     none !important;
    border:         none !important;
    margin-left:    -2px !important;
    min-width:      40px !important;
    max-width:      9950px !important;
    font-size:      12px !important;
    height:         44px !important;
    box-shadow:     none !important;
    color: #a9a9a9 !important; 
}
 
#urlbar:hover {
    border:         none !important;
    box-shadow:     none !important;
}
 
#urlbar[focused="true"] {
    
    border:         none !important;
}
 
/* Hide bookmark folder icons */
.bookmark-item > .toolbarbutton-icon {
    display:    none !important;
}
 
/* Increase bookmarks toolbar height */
 #PersonalToolbar {
    margin-top: 2px !important;
    height:     28px !important;
    border-top: 1px solid #9E9E9E !important;
}
 
/* Minor bookmarks toolbar spacing adjustments */
 #personal-bookmarks toolbarbutton.bookmark-item, #personal-bookmarks toolbarbutton {
    box-shadow:      none !important;
    margin:          -1px 0px -1px 2px !important;
    padding:         0px 5px !important;
    -moz-appearance: none !important; }
   
#personal-bookmarks toolbarbutton:hover {
    -moz-appearance: none !important;
    text-shadow:     none !important;
    color:           #000 !important;   }
 
/* Remove line under address bar */
 #navigator-toolbox::after{
    content:    none;
}
 
/* Affix hamburger menu to top right */
#PanelUI-button{
    position:   fixed;
    top:        1px;
    right:      4px;
}

#reload-button{
    position:   fixed;
    margin:    3px 0px 0px 0px !important;
    padding-right: 34px !important;
}


#new-tab-button{
    position:   fixed;
    margin:    3px 0px 0px 0px !important;
    padding-right: 34px !important;
}
 
/* Hide titlebar placeholder for caption buttons so that padding between tabs and address bar isn't as large */
.titlebar-placeholder[type="caption-buttons"] {
    -moz-box-ordinal-group: 1 !important;
    display:    none !important;
    padding-left: -50px;
}

/* Findbar customization */
@keyframes scale-in {
    0% {
        transform: scaleY(0);
    }
    100% {
        transform: scaleY(1);
    }
}

@keyframes scale-out {
    0% {
        transform: scaleY(1);
    }
    100% {
        transform: scaleY(0);
    }
}

.browserContainer {
    position: relative;
    background-color: #363636 !important;
}

findbar {
    animation: 0.2s scale-in;
    transform-origin: top center;
    background-color: #0c0c0d !important;
    padding: 6px 6px 6px 6px;
    border-color: #0c0c0d !important;
    border: 0 0 0 0 !important;
    position: absolute;
    top: -2px;
    right: 38px; 
}

findbar[hidden="true"] {
    animation: 0.2s scale-out;
}

findbar .findbar-container {
    padding: 0 !important;
    padding-inline-start: 0 !important;
    padding-inline-end: 0 !important;
}

findbar .findbar-container .findbar-textbox {
    padding: 6px 8px !important;
    background: #00b300 !important;
    border: 0px !important;
    box-shadow:     none !important;
    color: #ffffff !important;
}

findbar .findbar-container .findbar-find-previous,
findbar .findbar-container .findbar-find-next {
    background: #00b300 !important;
    background-color: #00b300 !important;
    border-color: #00b300 !important;
}

findbar .findbar-container .findbar-find-previous:hover, findbar .findbar-container .findbar-find-previous:focus,
findbar .findbar-container .findbar-find-next:hover,
findbar .findbar-container .findbar-find-next:focus {
    background-color: #00b300 !important;
}

findbar .findbar-button {
    color: #ffffff;
    border: 1px solid var(--backbutton-border-color);
    border-radius: var(--toolbarbutton-border-radius) !important;
}

findbar .findbar-closebutton {
    margin-right: 4px !important;
    padding-inline-end: 0 !important;
    position: relative;
    top: 6px;
}

/*Darken panels*/
.panel-arrow { 
    filter: invert(99%);
    opacity: .5;
}

.subviewbutton:hover,.toolbarbutton-1:hover,#appMenu-zoomReset-button:hover {
    color:#33ff66 !important;
    background-color: transparent !important;
}

.panel-subview-body,#appMenu-zoomReset-button {
    color: #a9a9a9 !important;
    background: #0c0c0d !important;
    box-shadow: none !important;
    text-shadow: none !important;
}

.panel-subview-footer,[class^="PanelUI-"] {
    color: #a9a9a9 !important;
    background: #0c0c0d !important; !important;
}

/*stops possible clashes with extension popups*/
 .webextension-popup-browser {
    background: #fff;
}

/*  Right click menu */
menupopup, popup,
popup > menu > menupopup,
menupopup > menu > menupopup {
    -moz-appearance: none !important;
    background: #0c0c0d !important;
    border-radius: 3px !important;
    padding: 2px 0px 2px 0px  !important;
    box-shadow: none !important;
}

menupopup menuseparator {
    -moz-appearance: none !important;
    border-bottom: 2px solid #282828;
    margin: 3px 0px 5px 0px !important;
    padding: 0px !important;
}

menupopup menu, menuitem{
    -moz-appearance: none !important;
    color: #a9a9a9!important;
}

menupopup menu:hover, menuitem:hover {
    -moz-appearance: none !important;
    color:#33ff66 !important;
    background-color: transparent !important;
}

#TabsToolbar .titlebar-placeholder {
  display: none !important;
}    

/*  Overflow menu */

.searchbar-textbox {
background-color: #00b300 !important;
color: #fff !important;   
}

#overflowMenu-customize-button:hover {
    background-color: #0c0c0d !important;
}