i dont know why, i have a invisible space in my layout, at the top and i tried to remove it but i doesn't work ...I've already tried margin:0, padding:0, etc...
And this is the css :
You had some unusual characters in your html, which were causing the issue. Just remove the first character from your codepen (the dots) and it'll work fine.
Indendation doesn't cause this problem, but if there are these invisible characters, they can cause various problems. I remember, I had a similar problem when my php API response looked good, but couldn't be parsed due to a similar character at the beginning of the response.
Here's your updated pen