feat: add a bunch of new Nebular demos (#1911)

src/app/pages/modal-overlays/window/window.component.scss

@@ -0,0 +1,38 @@
+@import '~bootstrap/scss/mixins/breakpoints';
+@import '~@nebular/theme/styles/global/breakpoints';
+
+@import '../../../@theme/styles/themes';
+
+@include nb-install-component() {
+  button + button {
+    margin-left: 2rem;
+  }
+
+  @include media-breakpoint-down(xxl) {
+    nb-card-body {
+      display: flex;
+    }
+
+    button {
+      flex: 1;
+      padding: 0.8rem;
+    }
+  }
+
+  @include media-breakpoint-down(is) {
+    nb-card-body {
+      display: block;
+    }
+
+    button {
+      + button {
+        margin-left: 0;
+      }
+
+      width: 100%;
+      display: block;
+      margin-bottom: 2rem;
+      padding: 0.75rem;
+    }
+  }
+}