Agree with the second floor’s point of view

You use margin-right:200px;

Do you want to leave space for the div on the right?

But the default width of div is 100%

So after you set margin-right:200px; the div width is actually still 100%

Because padding, margin, width, border are added It is the real width or height of the component

Please change

to

Test the code again ~

Why should I swallow the code? The class is gone