HTML errors

Can you link to a page using the default theme that has these errors?

Sure, I use a domain for testing purpose only. https://nakontra.com/
Here’s another WP with different plugins and themes but again all deactivated, 75 warnings and 13 errors. With the other two default themes is quite the same, only 1-2 warnings more.
I am going to install fresh new WP and see how is there going because I’ve never checked so far.

Wp 4.1 installed from the scratch: 34 warnings, 13 errors nakontra.com/SoccerPress/

Which validation service are you using? I get a pass: https://validator.w3.org/check?verbose=1&uri=http%3A%2F%2Fnakontra.com%2F

I already posted what I use: https://infohound.net/tidy/
Also, I saw that CSS found 8 errors and 54 warnings via w3.org: https://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fnakontra.com%2FSoccerPress&profile=css3&usermedium=all&warning=1&vextwarning=&lang=bg#css