Why I can't just use float:right?

Question

I am new to html and css. when I am using float: right, it doesn't show the result I want. that block doesn't showup in right place and it goes down. why it is happening?

https://code.sololearn.com/WR26Bggu5mO9/?ref=app

Answer 1

use box-sizing

https://code.sololearn.com/WlGUD18K3fi0/?ref=app

Answer 2

You should see it here ↓↓↓ :)
https://www.w3schools.com/css/css_float.asp

Answer 3

Could you share your code?

Answer 4

reduce .n3 width

Answer 5

@calvin I have posted in the post

Answer 6

thanks @catty @calvin

Answer 7

btw if I add a footer block in the code. it goes all the way near header block and stays under the main block. what can I do to solve that problem?