When the page content is just less than the viewable window height, using twentytwenty causes the page to increase in size, causing scrollbars. This reduces the image width, meaning that the page height is reduced and scrollbars disappear. The effect is that scrollbars blink in and out of existence.
When the page content is just less than the viewable window height, using twentytwenty causes the page to increase in size, causing scrollbars. This reduces the image width, meaning that the page height is reduced and scrollbars disappear. The effect is that scrollbars blink in and out of existence.
Bug in action: