只需取消navbar-fixed-bottom和navbar-fixed-top的position: fixed规则.或者，如果您不想更改它，请在tabbable类中添加margin-top: 43px规则.

Simply take off the position: fixed rule for navbar-fixed-bottom and navbar-fixed-top. Or if you would not like to change it, add margin-top: 43px rule to your tabbable class.