@UCyborg you were right about that it's Firefox fault not Aero glass , i think they fixed it in Firefox Nightly 66 i try to modified it, a little bugs, but it works fine i think
try this now :
/* Firefox Quantum userChrome.css tweaks ************************************************/
/* Github: https://github.com/aris-t2/customcssforfx ************************************/
/****************************************************************************************/
/* Glass8 ( http://www.glass8.eu/ ) required for 'Windows 7'-like window transparency */
@-moz-document url(chrome://browser/content/browser.xul) {
#main-window {
background-color: transparent !important;
-moz-appearance: -moz-win-glass !important;
}
}
#main-window:not([customizing]) .titlebar-button,
#main-window:not([customizing]) .titlebar-button:not(#titlebar-close) > .toolbarbutton-icon{
opacity: 0.0 !important;
}
#main-window:not([customizing]) .titlebar-button:hover {
opacity: 0.5 !important;
}
#main-window:not([customizing])
opacity: 0.1 !important;
background: red !important;
}
#titlebar-close):hover {
opacity: 0.1 !important;
background: red !important;
}
/* Firefox userChrome.css */
@namespace url("userChrome.xml#js");
toolbarbutton#characterencoding-button {
-moz-binding: url("userChrome.xml#js");
}
#main-window:not([customizing="true"]) toolbarbutton#characterencoding-button {
visibility: collapse;
}
tabpanels{
background:transparent none!important;