<div class="usa-accordion usa-accordion--bordered">

    <!-- Use the accurate heading level to maintain the document outline -->
    <h2 class="usa-accordion__heading">
        <button class="usa-accordion__button" aria-expanded="true" aria-controls="b-a1">
      First Amendment
    </button>
    </h2>
    <div id="b-a1" class="usa-accordion__content usa-prose">
        <p>Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government
            for a redress of grievances.</p>

    </div>

    <!-- Use the accurate heading level to maintain the document outline -->
    <h2 class="usa-accordion__heading">
        <button class="usa-accordion__button" aria-expanded="false" aria-controls="b-a2">
      Second Amendment
    </button>
    </h2>
    <div id="b-a2" class="usa-accordion__content usa-prose">
        <p>A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.</p>
        <ul>
            <li>This is a list item</li>
            <li>Another list item</li>
        </ul>

    </div>

    <!-- Use the accurate heading level to maintain the document outline -->
    <h2 class="usa-accordion__heading">
        <button class="usa-accordion__button" aria-expanded="false" aria-controls="b-a3">
      Third Amendment
    </button>
    </h2>
    <div id="b-a3" class="usa-accordion__content usa-prose">
        <p>No Soldier shall, in time of peace be quartered in any house, without the consent of the Owner, nor in time of war, but in a manner to be prescribed by law.</p>

    </div>

    <!-- Use the accurate heading level to maintain the document outline -->
    <h2 class="usa-accordion__heading">
        <button class="usa-accordion__button" aria-expanded="false" aria-controls="b-a4">
      Fourth Amendment
    </button>
    </h2>
    <div id="b-a4" class="usa-accordion__content usa-prose">
        <p>The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and
            particularly describing the place to be searched, and the persons or things to be seized.</p>

    </div>

    <!-- Use the accurate heading level to maintain the document outline -->
    <h2 class="usa-accordion__heading">
        <button class="usa-accordion__button" aria-expanded="false" aria-controls="b-a5">
      Fifth Amendment
    </button>
    </h2>
    <div id="b-a5" class="usa-accordion__content usa-prose">
        <p>No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War
            or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property,
            without due process of law; nor shall private property be taken for public use, without just compensation.</p>

    </div>

</div>

Add the usa-accordion--bordered class to your .usa-accordion to enable the visual border.

<div class="usa-accordion{%
  if accordion.variant %} usa-accordion--{{ accordion.variant }}{% endif %}"{%
  if accordion.multiselectable == true %} aria-multiselectable="true"{% endif %}>
  {% for item in accordion.items %}
  <!-- Use the accurate heading level to maintain the document outline -->
  <h2 class="usa-accordion__heading">
    <button class="usa-accordion__button"
      aria-expanded="{{ item.expanded | default('false') }}"
      aria-controls="{{ accordion.id_prefix }}{{ item.id }}">
      {{ item.title }}
    </button>
  </h2>
  <div id="{{ accordion.id_prefix }}{{ item.id }}" class="usa-accordion__content usa-prose">
    {{ item.content }}
  </div>
  {% endfor %}
</div>
package:
  name: uswds
  version: 2.0.3
uswds:
  path: ../../dist
accordion:
  items:
    - title: First Amendment
      id: a1
      expanded: true
      content: >
        <p>Congress shall make no law respecting an establishment of religion,
        or prohibiting the free exercise thereof; or abridging the freedom of
        speech, or of the press; or the right of the people peaceably to
        assemble, and to petition the Government for a redress of
        grievances.</p>
    - title: Second Amendment
      id: a2
      content: >
        <p>A well regulated Militia, being necessary to the security of a free
        State, the right of the people to keep and bear Arms, shall not be
        infringed.</p> <ul><li>This is a list item</li><li>Another list
        item</li></ul>
    - title: Third Amendment
      id: a3
      content: >
        <p>No Soldier shall, in time of peace be quartered in any house, without
        the consent of the Owner, nor in time of war, but in a manner to be
        prescribed by law.</p>
    - title: Fourth Amendment
      id: a4
      content: >
        <p>The right of the people to be secure in their persons, houses,
        papers, and effects, against unreasonable searches and seizures, shall
        not be violated, and no Warrants shall issue, but upon probable cause,
        supported by Oath or affirmation, and particularly describing the place
        to be searched, and the persons or things to be seized.</p>
    - title: Fifth Amendment
      id: a5
      content: >
        <p>No person shall be held to answer for a capital, or otherwise
        infamous crime, unless on a presentment or indictment of a Grand Jury,
        except in cases arising in the land or naval forces, or in the Militia,
        when in actual service in time of War or public danger; nor shall any
        person be subject for the same offence to be twice put in jeopardy of
        life or limb; nor shall be compelled in any criminal case to be a
        witness against himself, nor be deprived of life, liberty, or property,
        without due process of law; nor shall private property be taken for
        public use, without just compensation.</p>
  id_prefix: b-
  variant: bordered