Add x-govuk-summary-card styles

This doesn't exist in the design system yet. See:
alphagov/govuk-design-system-backlog#210

We need this component in the support interface. Add its styles from:
https://github.com/x-govuk/govuk-prototype-components/tree/main/x-govuk/components/summary-card

app/assets/stylesheets/_x-govuk-summary-card.scss

@@ -0,0 +1,81 @@
+.x-govuk-summary-card {
+  border: 1px solid $govuk-border-colour;
+
+  // Card header
+  .x-govuk-summary-card__header {
+    align-items: center;
+    background-color: govuk-colour("light-grey");
+    padding: govuk-spacing(3);
+
+    @include govuk-media-query($from: desktop) {
+      display: flex;
+      justify-content: space-between;
+      align-items: start;
+    }
+  }
+
+  .x-govuk-summary-card__title {
+    @include govuk-font($size: 19);
+    margin: 0;
+  }
+
+  .x-govuk-summary-card__meta {
+    @include govuk-font($size: 16);
+    display: block;
+    margin: 0;
+  }
+
+  .x-govuk-summary-card__actions {
+    @include govuk-font($size: 19);
+  }
+
+  .x-govuk-summary-card__actions-list {
+    width: 100%;
+    margin: 0;
+    padding: 0;
+  }
+
+  .x-govuk-summary-card__actions-list-item {
+    display: block;
+    white-space: nowrap;
+
+    @include govuk-media-query($from: desktop) {
+      display: inline-block;
+      margin-left: govuk-spacing(2);
+      text-align: right;
+    }
+  }
+
+  .x-govuk-summary-card__actions-list-item:first-child {
+    margin-left: 0;
+  }
+
+  // Card body
+  .x-govuk-summary-card__body {
+    @include govuk-font($size: 19);
+    padding: govuk-spacing(3);
+  }
+
+  .govuk-summary-list {
+    margin-bottom: 0;
+  }
+
+  .govuk-summary-list__row:last-child,
+  .govuk-summary-list__row:last-child > * {
+    border-bottom: 0;
+  }
+}
+
+.x-govuk-summary-card--large-title .x-govuk-summary-card__title {
+  @include govuk-font($size: 24, $weight: bold);
+}
+
+@media print {
+  .x-govuk-summary-card__header {
+    break-inside: avoid;
+  }
+
+  .x-govuk-summary-card__actions {
+    display: none;
+  }
+}

app/assets/stylesheets/main.sass.scss

@@ -4,6 +4,7 @@ $govuk-new-link-styles: true;
 @import "govuk-frontend/govuk/all";
 @import "_card";
 @import "_performance-table";
+@import "_x-govuk-summary-card";
 @import "dfe-autocomplete/src/dfe-autocomplete";
 
 .app-\!-inherit-colour {