Ghost/ghost/admin/app/components/modals/limits/multiple-newsletters.hbs

<div class="modal-content" data-test-modal="limits/multiple-newsletters">
    <header class="modal-header">
        <h1>Upgrade your plan</h1>
    </header>
    <button class="close" title="Close" type="button" {{on "click" @close}}>{{svg-jar "close"}}<span class="hidden">Close</span></button>

    <div class="modal-body">
        <p>
            {{#if @data.message}}
                {{html-safe @data.message}}
            {{else}}
                Your current plan doesn't support more newsletters.
            {{/if}}
        </p>
    </div>

    <div class="modal-footer">
        <button class="gh-btn" data-test-button="cancel-upgrade" type="button" {{on "click" @close}}>
            <span>Cancel</span>
        </button>

        <LinkTo @route="pro" class="gh-btn gh-btn-green" {{on "click" @close}} data-test-button="upgrade-plan">
            <span>Upgrade</span>
        </LinkTo>
    </div>
</div>