I received multiple “Increase in 404 pages on ‘mywebsite'” messages from Google Search Console after I’ve created new responsive theme for my blogs. I had no idea how to fix, tired of searching the answer without any solutions. I decided to check all my style.css and sure enough, the ones I used on the reported blogs had some errors. The errors were from commenting the unused part NOT fully due to many comment tag “/*” “*/”, some canceled out each others. When I removed all the comment tags, there isn’t any more report 404. The CSS caused the website to create a link to a url with title “/<div = /%3Cdiv” or “/<li = /%3Cli” whichever the case may be.