my firefox userChrome css

userChrome.css

@namespace url(http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul);
/* Adapted from: https://www.reddit.com/r/FirefoxCSS/comments/bm77hx/modern_firefox/ */

/* the little line under the title bar separating it from content */
#navigator-toolbox::after {
  height: 0px !important;
}

#personal-bookmarks #PlacesToolbarItems {
  -moz-box-pack: center;
}

#PersonalToolbar {
  height: 37px;
}

:root:not([uidensity="compact"]) #back-button > .toolbarbutton-icon {
  border: none;
}

#navigator-toolbox:hover > #PersonalToolbar {
  visibility: visible !important;
}

#urlbar:not([focused="true"]) {
  box-shadow: 0 0 5px 1px rgba(17, 17, 17, .06) !important;
  border:#FFFFFF solid 1px !important;
}

#nav-bar, .tabbrowser-tab[selected="true"] {
  box-shadow: 0px 0px 8px -6px #000000 !important;
}

#navigator-toolbox {
  box-shadow: 0px 0px 8px -6px #000000 !important;
}

#navigator-toolbox::after {
  border-bottom: 0px !important;
}

#PanelUI-button, #PanelUI-menu-button {
  border: none !important;
  padding-left: 0px !important;
  margin-inline-end: 1.4px !important;
}

.urlbar-go-button {
  display: none !important;
}

#TabsToolbar {
  max-height: 41px !important;
}

#nav-bar {
  height: 42px !important;padding:0 2px !important;
}

#urlbar {
  min-height: 30px !important;border-radius: 2em !important;
}

#back-button:not([disabled="true"]):not([open="true"]):not(:active) > .toolbarbutton-icon {
  background-color: white !important;
}

#back-button:not(:hover),#back-button:not(:hover) > .toolbarbutton-icon {
  background: transparent !important;
  border: none !important; 
  /*box-shadow:0px 0px 8px -6px #000000 !important;*/
}

#back-button:hover,#back-button:hover > .toolbarbutton-icon {
  border: none !important;
  /*border-radius: 2px !important;*/
}

.tab-background {
  margin-inline-start: -1px !important;
  margin-inline-end: -1px !important;
  border: 0 !important;
  border-image-width: 0 !important;
}

.titlebar-buttonbox-container {
  max-height: 30px !important;
}

.tabbrowser-tab[fadein] {
  max-width: 242px !important;
}

.tab-line {
  visibility: hidden !important;
}

/* Separator before and after tabs in titlebar */
.titlebar-spacer[type="pre-tabs"], .titlebar-spacer[type="post-tabs"] {
  border-inline-end: none !important;
  width: 12px !important;
}

.tabbrowser-tab:not([pinned]) .tab-close-button {
  display: -moz-box !important;
}

/* Separator between tabs */
.tabbrowser-tab::after, .tabbrowser-tab::before {
  border-left: 1px solid #989898 !important;
}

Screenshot