Ghost/ghost/admin/app/components/modals/post-preview.hbs

<div class="modal-content">
    <div class="flex flex-column h-100">
        <header class="modal-header gh-post-preview-header gh-post-preview-header-border" data-test-modal="preview-email">
            <div>
                <button class="gh-editor-back-button" title="Close" type="button" {{on "click" @close}}>
                    <span>{{svg-jar "arrow-left"}} Back</span>
                </button>
            </div>
            <div class="gh-post-preview-btn-group">
                <div class="gh-contentfilter gh-btn-group">
                    <button type="button" class="gh-btn {{if (eq this.tab "browser") "gh-btn-group-selected"}} gh-post-preview-mode" {{on "click" (fn this.changeTab "browser")}}><span>{{svg-jar "desktop"}}</span></button>
                    <button type="button" class="gh-btn {{if (eq this.tab "mobile") "gh-btn-group-selected"}} gh-post-preview-mode" {{on "click" (fn this.changeTab "mobile")}}><span>{{svg-jar "mobile-phone"}}</span></button>
                    {{#if (and (not-eq this.settings.membersSignupAccess "none") (not-eq this.settings.editorDefaultEmailRecipients "disabled"))}}
                        {{#if @data.post.isPost}}
                            <button type="button" class="gh-btn {{if (eq this.tab "email") "gh-btn-group-selected"}} gh-post-preview-mode" {{on "click" (fn this.changeTab "email")}}><span>{{svg-jar "email-unread"}}</span></button>
                        {{/if}}
                    {{/if}}
                    <button type="button" class="gh-btn {{if (eq this.tab "social") "gh-btn-group-selected"}} gh-post-preview-mode" {{on "click" (fn this.changeTab "social")}}><span>{{svg-jar "twitter"}}</span></button>
                </div>
            </div>

            {{#unless this.session.user.isContributor}}
                <GhPublishmenu
                    @post={{@data.post}}
                    @postStatus={{@data.post.status}}
                    @saveTask={{@data.saveTask}}
                    @setSaveType={{@data.setEditorSaveType}}
                    @uiContext="preview" />
            {{/unless}}
        </header>

        {{#if this.saveFirstTask.isRunning}}
            <GhLoadingSpinner />
        {{else}}
            {{#if (eq this.tab "browser")}}
                <Modals::PostPreview::Browser @post={{@data.post}} />
            {{/if}}

            {{#if (and (eq this.tab "mobile"))}}
                <Modals::PostPreview::Mobile @post={{@data.post}} />
            {{/if}}

            {{#if (and (eq this.tab "email") @data.post.isPost)}}
                <Modals::PostPreview::Email @post={{@data.post}} />
            {{/if}}

            {{#if (eq this.tab "social")}}
                <Modals::PostPreview::Social @post={{@data.post}} />
            {{/if}}
        {{/if}}
    </div>
</div>