CSS如何创建可滚动列表

I am trying to create a webpage which is made up of a header and bellow the header a list of items. I want the list of items to be vertically scrollable. I also would like the webpage to take up the entire window but not be bigger. Currently my problem is the list of items is not scrollable and instead extends far below the bottom of the window and this is causing the window to be scrollable. What should the I am trying to create a webpage which is made u