Add edit styling

src/panels/lovelace/cards/hui-spacing-card.ts

@@ -1,32 +1,64 @@
-import type { PropertyValues } from "lit";
-import { LitElement, html } from "lit";
-import { customElement } from "lit/decorators";
+import { mdiDotsHorizontal } from "@mdi/js";
+import { LitElement, html, css, nothing } from "lit";
+import { customElement, property } from "lit/decorators";
 import "../../../components/ha-card";
-import { hasConfigOrEntityChanged } from "../common/has-changed";
-import type { LovelaceCard, LovelaceCardEditor } from "../types";
+import "../../../components/ha-svg-icon";
+import type {
+  LovelaceCard,
+  LovelaceCardEditor,
+  LovelaceLayoutOptions,
+} from "../types";
 
 @customElement("hui-spacing-card")
 export class HuiSpacingCard extends LitElement implements LovelaceCard {
+  @property({ type: Boolean }) public preview = false;
+
   public static async getConfigElement(): Promise<LovelaceCardEditor> {
     await import("../editor/config-elements/hui-spacing-card-editor");
     return document.createElement("hui-spacing-card-editor");
   }
 
-  protected shouldUpdate(changedProps: PropertyValues): boolean {
-    return hasConfigOrEntityChanged(this, changedProps);
-  }
-
   public getCardSize(): number {
     return 1;
   }
 
+  public getLayoutOptions(): LovelaceLayoutOptions {
+    return {
+      grid_columns: 1,
+      grid_rows: 1,
+    };
+  }
+
   public setConfig(): void {
     // No config necessary
   }
 
   protected render() {
-    return html`<ha-card></ha-card>`;
+    if (!this.preview) {
+      return nothing;
+    }
+
+    return html`<ha-card>
+      <ha-svg-icon path=${mdiDotsHorizontal}></ha-svg-icon>
+    </ha-card>`;
   }
+
+  static styles = css`
+    :host {
+      display: block;
+      height: 100%;
+    }
+
+    ha-card {
+      background: none;
+      height: 100%;
+      display: flex;
+      justify-content: center;
+      align-items: center;
+      --mdc-icon-size: 40px;
+      --icon-primary-color: var(--divider-color);
+    }
+  `;
 }
 
 declare global {