Increase Banner Header Font Size on Mobile on THESE pages

I want to make the font size of the banner headers on the following links to 70px on MOBILE.

1) https://www.ilikestorytelling.com/mindful-marketing-retreats

2) https://www.ilikestorytelling.com/webinar-resources

3) https://www.ilikestorytelling.com/about

Tried the following code, but it only worked on some of the pages of my website:

@media screen and (max-width:640px) {
#mindful-marketing-retreats .banner-thumbnail-wrapper.has-description .desc-wrapper p>strong {
  font-size: 60px;
}   
}

If anyone has any guidance, it would be greatly appreciated!