Drop the right-hand sidebar on Stack Exchange sites at a somewhat larger width than the default. Have Tampermonkey or whatever installed, then click "Raw"

fat-content.user.js

// ==UserScript==
// @name          Fat Content
// @description   Drop the right-hand sidebar on Stack Exchange sites at a somewhat larger width than the default
// @author        Shog9
// @namespace     https://gist.github.com/Shog9
// @version       0.1
// @include       http*://stackoverflow.com/*
// @include       http*://*.stackoverflow.com/*
// @include       http*://dev.stackoverflow.com/*
// @include       http*://askubuntu.com/*
// @include       http*://superuser.com/*
// @include       http*://serverfault.com/*
// @include       http*://mathoverflow.net/*
// @include       http*://*.stackexchange.com/*
// @exclude       http*://chat.*.com/*
// ==/UserScript==


$("head").append(`<style>
@media screen and (max-width: 1160px) {
    html.html__responsive:not(.html__unpinned-leftnav) #mainbar,html.html__responsive:not(.html__unpinned-leftnav) .mainbar {
        width:100%;
        float: none
    }
}
</style>`);