Free WordPress WP Sticky Sidebar pluginFree
Plugin glues website’s sidebar, making it permanently visible while scrolling. Since sidebar is always visible it increases website’s usability, accessibility and therefore gets better click through rate.
By default, it uses “#secondary” css id under “Sticky Class” setting field and that should be modified for different themes to make them work. Don’t forget this, it’s a mandatory field for certain themes. Use additional margin top to fine tune sidebar position.
Sticky sidebar plugin will work out of box with some themes which use “#secondary” id for sidebar by default such as: Twenty Sixteen, Twenty Fourteen, Twenty Twelve, Total, Flat Bootstrap and many more… Plugin is localized (multi language support) and responsive (as far as your theme is).
Sticky Class: CSS class or id of the sidebar element desired to be sticky. Defaults to “#secondary”. This is mandatory field and it must be filled!
Container Class: Container element class or id. If left blank script will try to guess. It must be element that contains both sidebar and content. Usually it is #main, #main-content or #primary. Mostly this parameter is not needed for majority of themes.
Additional Top Margin: An additional top margin in pixels. Defaults to 0. …
Additional Bottom Margin: An additional bottom margin in pixels. Defaults to 0.
Disable if screen width is smaller than: desired number of pixels. It disables script on mobiles or any device which screen is not wide as entered number of pixels.
Update sidebar height: Troubleshooting option, try this if your sidebar loses its background color. True or False.
Disable at: front page, blog page, pages, posts, categories, tags, archives
Enable for specific posts and pages if previously disabled site wide.
Source from: WordPress.org