Hi, reading through the forum I can see I am not the only one struggling with the responsive behaviour of sidebars for some type of content. Without having sidebars fixed width while content flexible width it is impossible to avoid very narrow and very tall sidebars of text, especially using content/sidebar/sidebar layout.
I have one feature suggestion. What about to change sidebars to slide-out-from-side type (like menus) at certain breakpoints? The idea can be seen here: