Look thru the recent questions over here: https://www.reddit.com/r/FirefoxCSS/

Or ask about that issue there.

Couldn't find anything there that was relevant. Went back to 64 for now.

That is possibly a side effect from using a lightweight theme to style the user interface area.

Does this still happen with one of the builtin themes?

When I first upgraded to FF 57 someone on here told me that the the "fog" or "shadows" on those bars was a holdover from using Classic Theme Restorer on 56 and gave me the following code to get rid of it and move the open tabs bar. This code doesn't work with 65.

/* Transparent toolbar backgrounds */
#nav-bar, #PersonalToolbar {
background-color: transparent !important;
background-image: none !important;
}
/* Remove top line on nav bar */
#nav-bar {
box-shadow: none !important;
}

cor-el said

That is possibly a side effect from using a lightweight theme to style the user interface area. Does this still happen with one of the builtin themes?

Went back to 65 and the entire tabs bar is highlighted with all themes. In 64 only the open tab is highlighted.

I deleted the ClassicThemeRestorter.XPI file and edited the userChrome.css file and got rid of the fog/light shadow on the open tabs bar but it is still there on the Navbar. I don't see any reference to the background color of the Navbar in the userChrome.css file. I can live with it the way it is but would like the background of the Navbar to be transparent. Anyone have an idea as to how I can accomplish that?

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

/* TABS: on bottom */

1. navigator-toolbox toolbar:not(#nav-bar):not(#toolbar-menubar) {-moz-box-ordinal-group:10}
2. TabsToolbar {-moz-box-ordinal-group:1000!important}

1. TabsToolbar {

position: absolute !important;
bottom: 0 !important;
width: 100vw !important;

}

1. tabbrowser-tabs {

 width: 100vw !important;

}

1. main-window:not([chromehidden*="toolbar"]) #navigator-toolbox {padding-bottom: var(--tab-min-height) !important;}

/* TABS: height */

root {

--tab-toolbar-navbar-overlap: 0px !important;
--tab-min-height: 33px !important; /* adjust to suit your needs */

}

root #tabbrowser-tabs {

--tab-min-height: 33px !important; /* needs to be the same as above under :root */
--tab-min-width: 80px !important;

}

1. tabbrowser-tabs,
2. tabbrowser-tabs > .tabbrowser-arrowscrollbox,

.tabbrowser-tabs[positionpinnedtabs] > .tabbrowser-tab[pinned] {

 min-height: var(--tab-min-height) !important;
 max-height: var(--tab-min-height) !important;

}

/* drag space */ .titlebar-spacer[type=pre-tabs], .titlebar-spacer[type=post-tabs] {

 width: 40px;

}

/* Override vertical shifts when moving a tab */

1. navigator-toolbox[movingtab] > #titlebar > #TabsToolbar {

 padding-bottom: unset !important;

}

1. navigator-toolbox[movingtab] #tabbrowser-tabs {

 padding-bottom: unset !important;
 margin-bottom: unset !important;

}

1. navigator-toolbox[movingtab] > #nav-bar {

 margin-top: unset !important;

}

/* hide windows-controls */

1. TabsToolbar #window-controls {display:none!important;}

/* move caption buttons to right of Tab bar */

1. main-window[tabsintitlebar]:not([inFullscreen="true"]) #toolbar-menubar[autohide="true"] ~ #TabsToolbar .titlebar-buttonbox-container {

position: fixed !important;
right: 0 !important;
top: calc(6px + var(--tab-min-height)) !important;
display: block !important;
visibility: visible !important;

}

1. toolbar-menubar[autohide="true"] ~ #TabsToolbar /* Transparent toolbar backgrounds */
2. nav-bar, #PersonalToolbar {

 background-color: transparent !important;
 background-image: none !important;

}

If you use a lightweight theme then Firefox automatically adds shadow to text to ensure you always see some text regardless of the color of this theme. You will have to accept this text shadow.

No matter what theme I use I get the whole Navigation bar highlighted. Below is what I get without a userChrome.css file. After I add the file to move the Open tabs bar down that whole bar is highlighted.