Warnings:
Content-Security-Policy HTTP header: Bad content security policy: Source list contains duplicate source expression "*.sdn.szn.cz". All but the first instance will be ignored.
The “banner” role is unnecessary for element “header”.
The “navigation” role is unnecessary for element “nav”.
The “main” role is unnecessary for element “main”.
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
The “complementary” role is unnecessary for element “aside”.
Empty heading.
The “contentinfo” role is unnecessary for element “footer”.
The first occurrence of ID “accessibility-footer” was here.
Consider adding a “lang” attribute to the “html” start tag to declare the language of this document.
Errors:
Bad value “crossorigin” for attribute “crossorigin” on element “link”.
Bad value “previewimage” for attribute “rel” on element “link”: The string “previewimage” is not a registered keyword.
“=” in an unquoted attribute value. Probable causes: Attributes running together or a URL query string in an unquoted attribute value.
Element “style” not allowed as child of element “div” in this context. (Suppressing further errors from this subtree.)
CSS: “scrollbar-width”: Property “scrollbar-width” doesn't exist.
Attribute “amp-fx” not allowed on element “header” at this point.
Bad value “navigation” for attribute “role” on element “button”.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
CSS: “padding-top”: “NaN” is not a “padding-top” value.
Bad value “auto” for attribute “width” on element “iframe”: Expected a digit but saw “a” instead.
Bad value “auto” for attribute “height” on element “iframe”: Expected a digit but saw “a” instead.
Bad value “true” for attribute “allowfullscreen” on element “iframe”.
The “scrolling” attribute on the “iframe” element is obsolete. Use CSS instead.
The “frameborder” attribute on the “iframe” element is obsolete. Use CSS instead.
Bad value “” for attribute “sizes” on element “img”: Must not be empty.
Bad value “” for attribute “srcset” on element “img”: Must contain one or more image candidate strings.
CSS: “bottom-top”: Property “bottom-top” doesn't exist.
Duplicate ID “accessibility-footer”.
Czech Republic CZ