Custom Blog Posts do not come side by side in WordPress

I am making themes of WordPress. The cards I create with Bootstrap normally need to be side by side, but they come at the block element level. What should I do to keep blog posts side by side?

div class=container mt-5

    h3?php bloginfo(name); ?/h3


    ?php if (have_posts()) : while (have_posts()) : the_post(); ?

        div class=card-group 
            div class=card 
                div class=card-body 
                    ?php the_title( 'h5 class=card-title', '/h5' ); ?
                    p class=card-text?php the_excerpt(); ?/p
                    a class=btn btn-info href=?php the_permalink(); ?Devamını Oku/a
                /div
            /div
        /div

    ?php endwhile; endif; ?

/div