Question

    $(".section").each(function(i, el){
    var section = $('.section');
    var width = section.width();
    if (width < 960)
        section.attr('class', 'section-slim');
});

This seems to work fine, on browser refresh, how do I make it act when resized?
Ex: if someone makes their browser window smaller, it will add this class?

Answer 1

bind the event to jQuery’s “resize” event

$(window).on("resize load", function () {
    $(".section").each(function(i, el){
    var section = $('.section');
    var width = section.width();
    if (width <= 960) {
        section.attr('class', 'section-slim');
    }
})