Ghost/ghost/admin/app/components/editor-labs/modals/preview.hbs

<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"}} Editor</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>
        <div class="flex">
            <button
                type="button"
                class="gh-btn gh-btn-editor darkgrey gh-publish-trigger"
                {{on "click" @close}}
            >
                <span>Preview</span>
            </button>
             <button
                type="button"
                class="gh-btn gh-btn-editor darkgrey gh-publish-trigger"
                {{on "click" @data.togglePreviewPublish}}
            >
                <span>Publish</span>
            </button>
            <div class="settings-menu-toggle-spacer"></div>
        </div>
    </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>