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CSS

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HTML 

              
                <h1>Santa's Naughty or Nice List</h1>

<ul class="santas-list">
  <li>
    <list-item>
      <span slot="name">Priscilla Lloyd</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Reece Zavala</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Ann Wiggins</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Bentley Lloyd</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Ahmad Yang</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Callum Robertson</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Kailee Kidd</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Monica Kaufman</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Jeremiah Anthony</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Gracie Blankenship</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Heidi Tapia</span>
    </list-item>
  </li>
  <li>
    <list-item>
      <span slot="name">Kian Patel</span>
    </list-item>
  </li>
</ul>

<template id="list-item">
  <style>
    :host {
      display: grid;
      align-items: center;
      padding: 0.5rem;
      row-gap: 0.5rem;
      background-color: white;
      border-radius: 0.5rem;
      box-shadow: 0 0 4px -1px hsl(0 0% 35%);
    }

    @container list (inline-size > 400px) {
      :host {
        grid-template-columns: subgrid;
        grid-column: 1 / -1;
      }
    }

    .actions {
      display: flex;
      flex-wrap: wrap;
      gap: 1rem;
    }

    button {
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font: inherit;
      gap: 0.25em;
      border: 1px solid black;
      border-radius: 0.25em;
      padding: 0.25em 0.5em;
      text-align: center;
    }

    button:focus-visible {
      outline: 2px solid black;
      outline-offset: 2px;
    }

    [aria-pressed="false"] {
      min-width: calc-size(max-content, size + 1em);
    }

    [aria-pressed="true"] {
      background-color: green;
      color: white;

      &#naughty {
        background-color: firebrick;
      }
    }

    [aria-pressed="true"]::before {
      content: "✓";
    }
  </style>

  <span id="name" class="name">
    <slot name="name"></slot>
  </span>
  <div aria-labelledby="name" role="group" class="actions">
    <button id="nice" aria-pressed="true">Nice</button>
    <button id="naughty" aria-pressed="false">Naughty</button>
  </div>
</template>
!

CSS 

              
                * {
  box-sizing: border-box;
  margin: 0;
}

body {
  font-family: system-ui;
  background-color: whitesmoke;
}

h1 {
  font-family: cursive;
  text-align: center;
  padding: 1rem;
  text-wrap: pretty;
  font-weight: bold;
  color: firebrick;
  font-size: clamp(1.75rem, 8cqi, 4rem);
  line-height: 1.2;
}

.santas-list {
  list-style: none;
  padding: 0;
  inline-size: min(80ch, 100% - 2rem);
  margin: 5vh auto;
  display: grid;
  grid-template-columns: 1fr auto;
  container: list / inline-size;
  gap: 1rem;

  li {
    display: grid;
    grid-template-columns: subgrid;
    grid-column: 1 / -1;
  }
}
!

JS 

              
                const santasList = new BroadcastChannel("santasList");

customElements.define(
  "list-item",
  class extends HTMLElement {
    constructor() {
      super();
      const template = document.getElementById("list-item");
      const listItem = template.content;

      const shadowRoot = this.attachShadow({ mode: "open" }).appendChild(
        listItem.cloneNode(true)
      );
    }

    connectedCallback() {
      // Get child's name
      const nameSlot = this.querySelector('[slot="name"]');
      const name = nameSlot?.textContent;

      /*
       * Updates button state from both in-page button presses and broadcasts
       *
       * id: 'naughty'|'nice' - presssed button id
       * pressed: boolean - pressed button state
       * postUpdate: boolean - true if triggered from in-page button
       */
      const handleListUpdate = (id, pressed, postUpdate) => {
        const button = this.shadowRoot.getElementById(id);
        const otherButtonId = id === "nice" ? "naughty" : "nice";

        button.setAttribute("aria-pressed", `${pressed}`);
        this.shadowRoot
          .getElementById(otherButtonId)
          .setAttribute("aria-pressed", `${!pressed}`);

        if (postUpdate) {
          // Post message with updated list item button state
          santasList.postMessage({
            name,
            id,
            pressed
          });
        }
      };

      // Handle list item button clicks
      this.shadowRoot.addEventListener("click", (e) => {
        if (!e.target.closest("button")) return;

        const button = e.target;
        const ariaPressed =
          button.getAttribute("aria-pressed") === "true" ? false : true;

        handleListUpdate(button.id, ariaPressed, true);
      });

      // Respond to custom event containing broadcast message data
      document.addEventListener("update-list", ({ detail }) => {
        if (detail.name !== name) return;

        // Pass off to update list item button state
        handleListUpdate(detail.id, detail.pressed);
      });
    }
  }
);

// Custom event to share broadcast message data
const updateListEvent = (detail) =>
  document.dispatchEvent(new CustomEvent("update-list", { detail }));

// BroadcastChannel message event listener
santasList.addEventListener("message", ({ data }) => {
  const { name, id, pressed } = data;

  // Trigger custom event
  updateListEvent({ name, id, pressed });
});
!
999px

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