fix(tabs): resolve non-working Sass theme parameters

Author: adrianptrv

src/components/tabs/themes/shared/tab/tab.bootstrap.scss

@@ -64,6 +64,7 @@ $theme: $bootstrap;
 :host([selected]) {
     [part='tab-header'] {
         position: relative;
+        background: var-get($theme, 'item-active-background');
 
         &::before {
             box-shadow:
@@ -81,8 +82,7 @@ $theme: $bootstrap;
         &:focus,
         &:focus-within
         {
-            background: var-get($theme, 'item-hover-background');
-            z-index: 1;
+            background: var-get($theme, 'item-active-background');
         }
     }
 }

src/components/tabs/themes/shared/tab/tab.common.scss

@@ -34,6 +34,7 @@ $theme: $material;
         &:hover,
         &:focus-within {
             color: var-get($theme, 'item-active-color');
+            background: var-get($theme, 'item-active-background');
 
             ::slotted(igc-icon) {
                 color: var-get($theme, 'item-active-icon-color');

src/components/tabs/themes/shared/tab/tab.fluent.scss

@@ -23,7 +23,7 @@ $theme: $fluent;
             color: var-get($theme, 'item-hover-color');
 
             ::slotted(igc-icon) {
-                color: var-get($theme, 'item-hover-icon-color');
+                color: var-get($theme, 'item-active-icon-color');
             }
         }
     }

src/components/tabs/themes/shared/tab/tab.indigo.scss

@@ -20,3 +20,12 @@ $theme: $indigo;
 
     text-transform: uppercase;
 }
+
+:host([selected]) {
+    [part='tab-header'] {
+        &:hover,
+        &:focus-within {
+            background: var-get($theme, 'item-hover-background');
+        }
+    }
+}