CSS not working when screen width is smaller than 1024px

Replies: 0

I am building a website and one of the pages has two main titles, and I want to hide the default title. I added this line of css to hide it:

.post-2048 .title-post {
display:none;
}

It works for big screens, but whenever I switch to a screen which is 1024px or smaller, the default title all of a sudden reappears. What is causing this title to become visible again in this smaller screens and how can I solve it?

By the way, I have this problem for other CSS lines too. However, the majority of CSS lines work perfectly fine on both desktop and mobile view.

Thanks a lot in advance!
Twan