Whta do you mean?

i already send you the website. You can check source code.

THIS IS A HUGE ERROR. As far as I see you already have this problem in this website, MEANIG KRIESI.AT. Your logo alt has single quotes. You can see here how Matt explains how to use alt and it uses double quotes not single ones.
https://webmasters.googleblog.com/2007/12/using-alt-attributes-smartly.html

YOU HAVE MORE EXAMPLES HERE:
https://books.google.es/books?id=Dq9L3KkDOFIC&pg=PA396&lpg=PA396&dq=ALT+ATTRIBUTES+DOUBLE+QUOTES&source=bl&ots=3ArOLyD2HJ&sig=ACfU3U1CxJSlS6u1B-l1ecVrcvGpmaHBYQ&hl=es&sa=X&ved=2ahUKEwjns-WmuaPnAhWNERQKHdsXDu8Q6AEwBXoECAoQAQ#v=onepage&q=ALT%20ATTRIBUTES%20DOUBLE%20QUOTES&f=false

This is basic HTML.

Please, provide a solution for this error.