chromium/chrome/browser/resources/settings/autofill_page/passkey_edit_dialog.html

<style include="settings-shared passwords-shared md-select action-link">
    cr-icon-button {
      --cr-icon-button-icon-size: 16px;
      margin-inline-start: 2px;
    }

    #footnote {
      margin-inline-start: 2px;
      margin-top: 16px;
    }

    cr-input {
      --cr-input-error-display: none;
    }

    #websiteInput[invalid].has-error-message,
    #usernameInput {
      margin-top: var(--cr-form-field-bottom-spacing);
    }
    
    #usernameInput[invalid] {
      --cr-input-error-display: block;
      margin-top: var(--cr-form-field-bottom-spacing);
    }
</style>

<cr-dialog id="dialog" close-text="$i18n{close}" show-on-attach>
  <div slot="title" id="title">$i18n{editPasskeyDialogTitle}</div>
  <div slot="body">
    <cr-input id="websiteInput" label="$i18n{editPasskeySiteLabel}"
        placeholder="[[relyingPartyId]]" readonly="true">
    </cr-input>
    <cr-input id="usernameInput" label="$i18n{editPasskeyUsernameLabel}"
        value="{{username}}" invalid="[[usernameInputInvalid_]]"
        error-message="[[usernameInputErrorMessage_]]">
    </cr-input>
    <div id="footnote">[[dialogFootnote_]]</div>
  </div>
  <div slot="button-container">
    <cr-button id="cancel" class="cancel-button" on-click="onCancel_">
      $i18n{cancel}
    </cr-button>
    <cr-button id="actionButton" class="action-button"
        on-click="onSaveButtonClick_" disabled="[[usernameInputInvalid_]]">
      $i18n{save}
    </cr-button>
  </div>
</cr-dialog>