Two different post template for two different screen size

Hi there,

Unfortunately I'm not aware of a solution for this.

OK so for that cause can I show a sidebar smaller than 640px I cant display the sidebar. Check the website and responsiveness and after being smaller than 640px I want to show the sidebar with 1 post box, so help me with that.

Don't think that'll looking good on a small screen, but give it a try:

@media (max-width: 640px) {
.blog #main {
        grid-template-columns: repeat(1, 1fr);
    }
    .site-content .content-area {
        width: 70% !important;
    }
    .blog .is-right-sidebar {
        width: 30%;
    }
    .site-content {
        flex-direction: row !important;
    }
    div#right-sidebar {
    display: block !important;
    }
}

Ya looking bad btw thanks for the answer. I can use it in the future.

You are welcome :)