zulip/static/templates/dialog_widget.hbs

<div class="micromodal" id="dialog_widget_modal" aria-hidden="true">
    <div class="modal__overlay" tabindex="-1" data-micromodal-close>
        <div {{#if id}}id="{{id}}" {{/if}}class="modal__container" role="dialog" aria-modal="true" aria-labelledby="dialog_title">
            <header class="modal__header">
                <h1 class="modal__title dialog_heading">
                    {{{ heading_text }}}
                    {{#if link}}
                    {{> help_link_widget }}
                    {{/if}}
                </h1>
                <button class="modal__close" aria-label="{{t 'Close modal' }}" data-micromodal-close></button>
            </header>
            <main class="modal__content">
                <div class="alert" id="dialog_error"></div>
                {{{ html_body }}}
            </main>
            <footer class="modal__footer">
                {{#unless single_footer_button}}
                <button class="modal__btn dialog_cancel_button" aria-label="{{t 'Close this dialog window' }}" data-micromodal-close>{{t "Cancel" }}</button>
                {{/unless}}
                <button class="modal__btn dialog_submit_button"{{#if single_footer_button}} aria-label="{{t 'Close this dialog window' }}" data-micromodal-close{{/if}}>
                    <span>{{{ html_submit_button }}}</span>
                    <div class="modal__spinner"></div>
                </button>
            </footer>
        </div>
    </div>
</div>