function waitForElement(selector, callback) {
  const element = document.querySelector(selector);
  if (element) {
    callback(element);
  } else {
    setTimeout(() => {
      waitForElement(selector, callback);
    }, 500);
  }
}

function modifyHeaderElement(headerElement) {
  const pricingModel = document.querySelector("#app > div > main > div > div > div > div.v-card__text > div.container.px-0.container--fluid > div > div:nth-child(2) > div.my-4.v-card.v-sheet.v-sheet--outlined.theme--dark > div.v-card__text > div > div > div:nth-child(1) > div > div.v-card__text.headline.text-center.px-0");
  const pricing_model = pricingModel.textContent.trim();
  const exclamationMark = document.createElement('span');

  if (pricing_model === 'CPC GOAL' || pricing_model === 'CPM GOAL') {
    const priceElements = document.querySelectorAll("#app > div > main > div > div > div > div.v-card__text > div.container.px-0.container--fluid > div > div:nth-child(2) > div.my-4.v-card.v-sheet.v-sheet--outlined.theme--dark > div.v-card__text > div > div > div > div > div.v-card__text.headline.text-center.px-0");
    const lastPriceElement = priceElements[priceElements.length - 1];
    const price = lastPriceElement.textContent;
    exclamationMark.textContent = ' [' + pricing_model + ' = ' + lastPriceElement + price + ']';
    exclamationMark.style.color = 'Violet';
  } else {
    const priceElement = document.querySelector("#app > div > main > div > div > div > div.v-card__text > div.container.px-0.container--fluid > div > div:nth-child(2) > div.my-4.v-card.v-sheet.v-sheet--outlined.theme--dark > div.v-card__text > div > div > div:nth-child(3) > div > div.v-card__text.headline.text-center.px-0");
    const price = parseFloat(priceElement.textContent);
    const priceboxPriceElement = document.querySelector("#app > div > main > div > div > div > div.v-card__text > div.container.px-0.container--fluid > div > div:nth-child(2) > div.my-4.v-card.v-sheet.v-sheet--outlined.theme--dark > div.v-card__text > div > div > div:nth-child(4) > div > div.v-card__text.headline.text-center.px-0");
    const priceboxPrice = parseFloat(priceboxPriceElement.textContent);
    const divisionResult = price / priceboxPrice;
    exclamationMark.textContent = ' [delta = ' + divisionResult.toFixed(1) + ']';

    if (divisionResult < 3) {
      exclamationMark.style.color = 'Lime';
    } else {
      exclamationMark.style.color = 'FireBrick';
    }
  }

  headerElement.textContent = 'Price info   ';
  headerElement.appendChild(exclamationMark);
const observer = n