MOBILE-3363 styles: Style dark mode action sheet buttons

src/app/app.scss

@@ -666,11 +666,12 @@ ion-app.app-root {
       overflow: auto;
   }
 
-  .action-sheet-wrapper {
+  ion-action-sheet .action-sheet-wrapper .action-sheet-container {
     .action-sheet-button.action-sheet-cancel {
       color: $core-action-sheet-cancel-color;
       @include darkmode() {
         color: $core-dark-action-sheet-cancel-color;
+        background-color: $black;
       }
     }
     .action-sheet-selected {

src/core/login/login.scss

@@ -30,6 +30,12 @@ ion-app.app-root page-core-login-site {
             border-color: $core-dark-login-box-background-border;
             color: $core-dark-login-box-text-color;
         }
+
+        .item {
+            @include darkmode() {
+                background: $core-dark-login-box-background-color;
+            }
+        }
     }
 
     .core-sitename, .core-siteurl {

src/theme/dark.scss

@@ -23,6 +23,7 @@ ion-app.app-root {
 
       &.action-sheet-selected {
         color: $core-color;
+        background-color: $black;
       }
       &.activated {
         background-color: $black;

src/theme/variables.scss

@@ -90,7 +90,7 @@ $inverted-contrast: $primary !default;
 
 $primary-dark: lighten($primary, 10%) !default;
 $secondary-dark: mix($secondary, white, 20%) !default;
-$danger-dark: mix($danger, white, 20%) !default;
+$danger-dark: mix($danger, white, 80%) !default;
 $warning-dark: mix($warning, white, 20%) !default;
 $success-dark: mix($success, white, 20%) !default;
 $info-dark: mix($info, white, 20%) !default;