Just a little snippet for Tom

pushing-fragments.js

F.visibleTextFragments.push(newFragment);

let text = `<p>`;

if (F.visibleTextFragments.length > 0) {
    let visibleText = F.visibleTextFragments.reduce(function(visibleFragments, thisFragment) {
        return visibleFragments + thisFragment;
    });
    text += `<span class="visible">${visibleText}</span>`;
}

if (F.invisibleTextFragments.length > 0) {
    let invisibleText = F.invisibleTextFragments.reduce(function(invisibleFragments, thisFragment) {
        return invisibleFragments + thisFragment;
    });
    text += `<span class="invisible">${invisibleText}</span>`;
}

text += `</p>`;