Remove leftover styles from NDDB

app/styles/_ui.scss

@@ -67,7 +67,6 @@
 @import 'ui/avatar-stack';
 @import 'ui/commit-attribution';
 @import 'ui/fancy-text-box';
-@import 'ui/notification-banner';
 @import 'ui/merge-status';
 @import 'ui/rebase-status';
 @import 'ui/cloneable-repository-filter-list';

app/styles/_variables.scss

@@ -423,11 +423,6 @@ $overlay-background-color: rgba(0, 0, 0, 0.4);
   --path-segment-background: #{$blue-000};
   --path-segment-padding: var(--spacing-third);
 
-  /** Diverging notification banner colors */
-  --notification-banner-background: #{$blue-000};
-  --notification-banner-border-color: #{$blue-200};
-  --notification-ref-background: rgba(255, 255, 255, 0.75);
-
   // http://easings.net/#easeOutBack
   --easing-ease-out-back: cubic-bezier(0.175, 0.885, 0.32, 1.275);
 

app/styles/themes/_dark.scss

@@ -328,11 +328,6 @@ body.theme-dark {
     filter: #{'invert()'} grayscale(1) brightness(8) contrast(0.6);
   }
 
-  /** Diverging notification banner colors */
-  --notification-banner-background: #{$gray-800};
-  --notification-banner-border-color: #{$gray-700};
-  --notification-ref-background: #{$gray-700};
-
   /** merge/rebase status indicators */
   --status-pending-color: #{$yellow-700};
   --status-error-color: #{$red-500};

app/styles/ui/_notification-banner.scss

@@ -1,102 +0,0 @@
-@import '../mixins';
-
-.notification-banner + .compare-form {
-  border-top: var(--base-border);
-}
-
-.notification-banner {
-  background: var(--notification-banner-background);
-  border: var(--base-border);
-  border-color: var(--notification-banner-border-color);
-  border-radius: var(--border-radius);
-  display: flex;
-  padding: var(--spacing);
-  position: relative;
-
-  .notification-icon {
-    margin-right: var(--spacing-half);
-  }
-
-  &-content {
-    display: flex;
-    flex-wrap: wrap;
-
-    p {
-      flex-grow: 1;
-      font-size: var(--font-size-sm);
-      margin: 0;
-      padding-right: var(--spacing-double); // Extra space for the close button
-
-      & + p {
-        margin-top: var(--spacing-half);
-      }
-    }
-  }
-
-  @include close-button;
-
-  .ref-component {
-    background: var(--notification-ref-background);
-    word-break: normal;
-  }
-
-  .close {
-    position: absolute;
-    margin: 0;
-    top: var(--spacing);
-    right: var(--spacing);
-    text-align: center;
-
-    .octicon {
-      height: 12px;
-    }
-  }
-}
-
-.diverge-banner {
-  margin: var(--spacing-half);
-  overflow: hidden;
-
-  &-enter {
-    max-height: 0;
-    opacity: 0;
-
-    &-active {
-      max-height: 200px;
-      opacity: 1;
-      transition: all var(--undo-animation-duration) cubic-bezier(0, 0, 0.2, 1);
-    }
-  }
-
-  &-exit {
-    max-height: 200px;
-
-    &-active {
-      max-height: 0;
-      opacity: 1;
-      transition: max-height 300ms cubic-bezier(0.4, 0, 0.2, 1);
-
-      .diverge-banner {
-        transform: translateX(-102%);
-        opacity: 0;
-        transition: all 180ms cubic-bezier(0.4, 0, 1, 1);
-      }
-    }
-  }
-
-  &-wrapper {
-    overflow: hidden;
-    box-shadow: inset 0 -1px var(--box-border-color);
-  }
-}
-
-.notification-banner-content-body {
-  margin-bottom: var(--spacing-half);
-}
-
-.notification-banner-content {
-  .button-component {
-    margin-top: var(--spacing-half);
-    margin-right: var(--spacing-half);
-  }
-}