copy and paste this in your browsers' console...

create_place_holder.js

const walk = document.createTreeWalker(document.body, NodeFilter.SHOW_TEXT, null, false);
const delay = [];
while (true) {
    const node = walk.nextNode();
    if (!node) break;
    if (!node.textContent.trim()) continue;
    const { parentElement } = node;
    if (parentElement.tagName === 'STYLE') continue;
    const { color, display } = getComputedStyle(parentElement);
    if (display === 'inline') {
        parentElement.style.backgroundColor = color;
    } else {
        const newNode = document.createElement('span');
        newNode.innerHTML = node.textContent;
        newNode.style.backgroundColor = color;
        delay.push([node, newNode]);
    }
}
for (let [o, n] of delay) {
    o.replaceWith(n);
}