diff --git a/src/tabbar/unselected_tab/_static_separator.scss b/src/tabbar/unselected_tab/_static_separator.scss
index 8bdde1f..77a4745 100644
--- a/src/tabbar/unselected_tab/_static_separator.scss
+++ b/src/tabbar/unselected_tab/_static_separator.scss
@@ -1,38 +1,40 @@
-.tabbrowser-tab[first-visible-tab]::before,
-.tabbrowser-tab::after,
-#tabbrowser-tabs[movingtab] > #tabbrowser-arrowscrollbox > .tabbrowser-tab[visuallyselected]::before {
+.tabbrowser-tab[first-visible-tab="true"] .tab-background::before,
+.tab-background::after {
   content: "";
+}
+
+.tab-background::before,
+.tab-background::after {
+  /* Box Model */
   display: block;
+  position: absolute;
+
+  /* Position */
+  top: 50%;
+  transform:  translateY(calc(-50% + 1px)) !important;
+
+  /* Bar shape */
+  width: 0px;
+  height: 100%;
+
+  /* Bar Color */
+  opacity: 0.3;
+  border-right: 1px solid var(--lwt-background-tab-separator-color, currentColor) !important;
 }
-.tabbrowser-tab::before,
-.tabbrowser-tab::after {
-  --tab-divide-line: 1px solid var(--lwt-background-tab-separator-color, currentColor);
-  border-left: var(--tab-divide-line) !important;
-  margin-block: 5px 4px !important;
-  opacity: 0.3 !important;
-}
-.tabbrowser-tab::before {
-  margin-inline-start: -1px !important;
+.tab-background::after {
+  right: 0;
 }
 
-.tabbrowser-tab[first-visible-tab]::before,
-:root[tabsintitlebar]:not([extradragspace]) #toolbar-menubar[autohide="true"] + #TabsToolbar .tabbrowser-tab::after,
-.tabbrowser-tab:hover::after,
-#tabbrowser-tabs:not([movingtab]) > #tabbrowser-arrowscrollbox > .tabbrowser-tab[beforehovered]::after,
-.tabbrowser-tab[multiselected]::after,
-#tabbrowser-tabs:not([movingtab]) > #tabbrowser-arrowscrollbox > .tabbrowser-tab[before-multiselected]::after {
-  margin-top: var(--tabs-top-border-width) !important;
-  margin-bottom: 0 !important;
+.tabbrowser-tab[visuallyselected] .tab-background::before,
+.tabbrowser-tab[visuallyselected] .tab-background::after,
+.tabbrowser-tab[beforeselected-visible] .tab-background::after {
+  opacity: 0;
 }
 
-/* Selected - Hide */
-.tabbrowser-tab[first-visible-tab][visuallyselected]::before,
-#tabbrowser-tabs:not([movingtab]) > #tabbrowser-arrowscrollbox > .tabbrowser-tab[beforeselected-visible]::after,
-#tabbrowser-tabs[movingtab] > #tabbrowser-arrowscrollbox > .tabbrowser-tab[visuallyselected]::before,
-.tabbrowser-tab[visuallyselected]::after {
-  --tabs-border-color: transparent;
-  border-color: var(--tabs-border-color) !important;
-  margin-top: 0 !important;
-  margin-bottom: 0 !important;
-  opacity: 1 !important;
+/* Animate */
+@include Animate {
+  .tab-background::before,
+  .tab-background::after {
+    transition: opacity 0.2s var(--animation-easing-function); /* cubic-bezier(.07, .95, 0, 1) */
+  }
 }