Help debug CSS, I've been working on it for a few days, _html/css_WEB-ITnose

This is the menu I designed, you can see it on this website,
http://www.hadoop.so/

But I found that the intervals between the menus are too big, but I used CSS is also border-left=1px, border-right=1px
but it looks much larger than 1PX,


My menu is imitated from https://flippa.com/, he The website does not have this problem,

Can you help me take a look, it has been debugging for a few days
Let the menu intervals be like that website

Reply to the discussion (solution )

plus

Why does another website flippa.com/ have this effect without adding float: left;
Haha, I don’t understand either

My opening is so slow. Is it a problem with the network speed (⊙_⊙)?