Nimm das als Inspiration und bastel dir was schönes... 
CSS
/** PopUp 3-Punkte-Button **/
/* Separator */
panel-list {
--fxview-element-background-hover: rgb(0,150,0) !important;
--button-background-color-hover: rgb(0,150,0) !important;
border: 2px ridge rgb(211,211,211) !important;
border-radius: 10px !important;
background-color: rgb(40,40,42) !important;
padding: 5px !important;
& > hr {
border-top: 2px ridge rgb(0,128,0) !important;
height: 0 !important;
margin: 2px 0 !important;
}
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-move-tab"] {
background-image: url("file:///E:/ICONS/FF/move-tab.png") !important;
}
/* Untermenü */
panel-list > panel-item[data-l10n-id="fxviewtabrow-move-tab-start"] {
background-image: url("file:///E:/ICONS/FF/arrow-start.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-move-tab-end"] {
background-image: url("file:///E:/ICONS/FF/arrow-stop.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-move-tab-window"] {
background-image: url("file:///E:/ICONS/FF/window-new.png") !important;
}
/* Ende Untermenü */
panel-list > panel-item[data-l10n-id="fxviewtabrow-pin-tab"] {
border-radius: 3px !important;
background-image: url("file:///E:/ICONS/FF/pin-grün.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-unpin-tab"] {
background: url("file:///E:/ICONS/FF/pin-rot.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-mute-tab"] {
background-image: url("file:///E:/ICONS/FF/sound-off.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-unmute-tab"] {
background-image: url("file:///E:/ICONS/FF/sound-on.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-copy-link"] {
background-image: url("file:///E:/ICONS/FF/copy.png") !important;
}
panel-list > panel-item[data-l10n-id="fxviewtabrow-send-to-device"] {
background-image: url("file:///E:/ICONS/FF/share2.png") !important;
}
/* Untermenü */
#send-tab-menu > panel-item[device-id="f81c820bcbd0e38f355b4f3ad6771142"] {
background-image: url("file:///E:/ICONS/FF/Laptop16.png") !important;
}
/* Ende Untermenü */
panel-list > panel-item[data-l10n-id="fxviewtabrow-open-in-window"],
panel-list > panel-item[data-l10n-id="fxviewtabrow-open-in-private-window"] {
background-image: url("file:///E:/ICONS/FF/window-new.png") !important;
}
panel-list > panel-item[data-l10n-id="firefoxview-history-context-delete"] {
background-image: url("file:///E:/ICONS/FF/Trashcan.png") !important;
}
panel-list > panel-item[data-l10n-id="firefoxview-history-context-forget-site"] {
background-image: url("file:///E:/ICONS/FF/cross3.png") !important;
}
panel-list > panel-item {
border-radius: 3px !important;
background-repeat: no-repeat !important;
background-position: 5px 3px !important;
}
panel-list > panel-item:hover {
background-color: rgb(0,150,0) !important;
}
button[role="menuitem"] {
border-radius: 3px !important;
padding: 3px 5px 3px 10px !important;
margin-left: 21px !important;
}
