When a user presses the tab key, a button appears at the top of the page, with the label “Skip to section”. Each time the user presses the tab key, the text updates to indicate the next available section to skip to. The user can then select a section to skip to by pressing the return key. When all sections have been skipped through, pressing the tab key again closes the skip link button. Users can navigate forward and backward through the available skip links by using the tab key and shift+tab key combination, respectively.
默认的配置：
