flex-grow : 1; // this means that the div will grow in same proportion as the window-size
flex-shrink : 1; // this means that the div will shrink in same proportion as the window-size
flex-basis : 0; // this means that the div does not have a starting value as such and will take up screen as per the screen size available for.e.g:- if 3 divs are in the wrapper then each div will take 33%.
flex：1表示以上內容，翻譯過來就是
flex-grow : 1; // 這意味着div將以與窗口大小相同的比例增長
flex-shrink : 1; // 這意味着div將以與窗口大小相同的比例縮小
flex-basis : 0; // 這意味着div沒有這樣的起始值，並且將根據可用的屏幕大小占用屏幕。例如： - 如果包裝器中有3個div，則每個div將占用33％。