TB - untere Startseite und Kopfzeilen-Reiter in weiß,keine Farbe mehr wie Verlauf oder Grau-Blau.

/* Farbverlauf TB Kopfzeile */
#msgHeaderView {
background: linear-gradient(#BA78AB, #666699) !important;
}

/* Farbverlauf TB Ordnerbaum */
#folderPane {
    appearance: none !important;
    background: linear-gradient(#BA78AB, #666699) !important;
}


/* Schrift Konten-Ordnerbaum-(Größe > Art > Höhe) */
#folderTree treechildren::-moz-tree-cell-text {
font-size: 21px !important;	/* Schriftgröße */
font-family: Arial Black !important;	/* Schriftart */ }
#folderTree > treechildren::-moz-tree-row {
height: 10px !important; }



@-moz-document url-prefix("chrome://messenger/content/messengercompose/messengercompose.xhtml") {
#msgSubject {
  font-size: 21px !important;
  font-weight: bold !important;
  font-family: Arial Black !important; }

}

/* Threadpane-(Schriftgrösse in Themenbereich/Nachrichtenliste)-font size, Farbe: #BA78AB, #DBA2CC */
#threadTree  {
font-size: 30px !important; 
font-family: Arial Black !important; 
background-color: #9FA2D5 !important; }

/* Set Line Spacing In Thread Pane */   
/* Zeilenabstand im Thema-Fensterbereich/Nachrichtenliste festlegen */
#threadTree > treechildren::-moz-tree-row {
font-family: Arial Black !important; 
height: 10px !important; }



#folderTree > #DBA2CC treechildren::-moz-tree-cell-text(isServer-true) {
color: black !important;
background-color: #DBA2CC !important; }



/* Scrollbar Farbverlauf FF innerhalb vom Firefox */

:root{
   
  /* Farbe 1: Thumb - Farbe 2: Hintergrund*/
  scrollbar-color: #CC6699 #666699 !important;
  
}

/* Scrollbar farbig about und Webseiten */

:root{

/* Farbe 1: Thumb - Farbe 2: Hintergund*/
scrollbar-color: #CC6699 #666699;

}


/* Eigene Anpassung Hintergrundfarbe */
#navigator-toolbox > toolbar:not(#TabsToolbar):not(#toolbar-menubar), .browserContainer > findbar, #browser-bottombox {
background-color: DBA2CC !important;
}

#navigation-toolbox {
    background-color: #666699 !important;
}

/* Nicht selektierter Tab und Mailbar */
#tabs-toolbar .tabmail-tab .tab-background,
#mail-bar3 {
    background-image: none !important;
    background-color: #DBA2CC !important;
}
/* Selektierter Tab */
#tabs-toolbar .tabmail-tab[selected] .tab-background {
    background-image: none !important;
    background-color: #bc5a97 !important;                  
}



#threadPane {
    min-height: 83px !important;
background-color: #9FA2D5 !important; 
}



#msgHeaderView {
  min-height: 88px !important;
}


#header-view-toolbar {
background: #666699 !important; }

#hdrSmartReplyButton, #hdrForwardButton, #hdrTrashButton, #otherActionsButton {
background-color: #DBA2CC !important; }



#expandedfromLabel,
#expandedHeadersBottomBox .headerName {
    color: #ffffff !important;
}

#expandedsubjectBox {
font-size: 13px !important;    
}


.tree-table  { 
  background-color: #b5b5da !important; 
 }



#accountCentral {
background-color: #DBA2CC !important;
color: #ffffff !important;
}

.scrollbox-clip > scrollbox[orient="vertical"] {
    max-height: 600px !important;
    overflow: auto !important;
}

/*Schriftfarbe der Menüleiste*/
.menubar-text{
color: #fff !important;}

/* Hintergrund der ganzen Menu-Bar setzen */
#mail-menubar {
background: #bc5a97!important;}


#toolbar-menubar {
  background: #8888C1 !important;
}

#TabsToolbar {
  background: #666699 !important;
}

/* Schriftfarbe in  TB-Kopfzelle (Von, Betreff + An). */
.header-row-grow > label {
    opacity: 1 !important;
    font-weight: bold !important;
    color: #fff !important;
}



/* Schriftfarbe der E-Mailkonten und Tableiste auf Schwarz) in der FolderPane. */
li[is="folder-tree-row"] span.name {
    color: #000 !important;
}

/* Schriftfarbe der Tabs. */
.tabmail-tab .tab-text {
    color: #000 !important;
}


/* Schriftfarbe in der Kopfzeile ("Betreff, Beteiligte, Datum") der ThreadPane. */
.tree-table-header tr > th > div > button,
.tree-table-header tr > th > button {
    background-color: #666699 !important;
    color: #FFF !important;
}
.tree-table-header tr > th > div > button:hover,
.tree-table-header tr > th > button:hover {
    background-color: #666699 !important;
    color: #000 !important;
}