Errors:
Bad value “https://api.w.org/” for attribute “rel” on element “link”: The string “https://api.w.org/” is not a registered keyword.
Bad value for attribute “srcset” on element “img”: Width for image “https://www.ideaxidea.com…03b26ebb0c8d9-458x350.png” is identical to width for image “https://www.ideaxidea.com…03b26ebb0c8d9-458x350.png”.
Bad value for attribute “srcset” on element “img”: Width for image “https://www.ideaxidea.com…83e001539c2102510c1-1.png” is identical to width for image “https://www.ideaxidea.com…83e001539c2102510c1-1.png”.
Bad value for attribute “srcset” on element “img”: Width for image “https://www.ideaxidea.com…ds/2017/08/61ecOt8E7L.jpg” is identical to width for image “https://www.ideaxidea.com…ds/2017/08/61ecOt8E7L.jpg”.
Bad value for attribute “srcset” on element “img”: Width for image “https://www.ideaxidea.com…/2017/08/shibata-book.jpg” is identical to width for image “https://www.ideaxidea.com…/2017/08/shibata-book.jpg”.
Bad value for attribute “srcset” on element “img”: Width for image “https://www.ideaxidea.com…ds/2017/07/61j4iKThUL.jpg” is identical to width for image “https://www.ideaxidea.com…ds/2017/07/61j4iKThUL.jpg”.
Bad element name “fb:like-box”: Code point “U+003A” is not allowed
Warnings:
The “banner” role is unnecessary for element “header”.
The “navigation” role is unnecessary for element “nav”.
The “main” role is unnecessary for element “main”.
The “complementary” role is unnecessary for element “aside”.
Section lacks heading. Consider using “h2”-“h6” elements to add identifying headings to all sections.
Element name “fb:like-box” cannot be represented as XML 1.0.
The “border” attribute is obsolete. Consider specifying “img { border: 0; }” in CSS instead.
The “contentinfo” role is unnecessary for element “footer”.
This document appears to be written in Japanese but the “html” start tag has “lang="en-US"”. Consider using “lang="ja"” (or variant) instead.
Japan JP