Empty characters just below body class=" ?

Hello Sami, i started a forum topic earlier about “mysterious line on top” after i created individual category pages from main index.php.

Index looks just fine but all the category pages (on main menu) are 18px lower than on index and background is visible(don’t know why)it seams that category body is that much lower, pls see screenshot 1 screenshot 2

I tried already:
1.copying default header.php from the theme (didn’t work)
2.creating new category.php from default theme index.php (didn’t work)
3.creating new category.php from default theme archive.php (didn’t work)
4.editing css (body,wrapper,header,……..etc) (didn’t work only main body work with margin-top:-18px; but also changes the index.

After checking with w3.org i see few errors, pls see screenshot not sure what this means (cant find it)…

My WordPress installation is by default on my first language and i didn’t add or edit any language files, also this is my test site so there is no plugins (beside Jetpack) on it.

Running out of ideas…….need help……..thanx

Thanks in advance…..

[Moderator note: You’re excluding all other volunteers when addressing “Sami”.]