delete css main core

git-svn-id: https://plugins.svn.wordpress.org/yuzo-related-post/trunk@940611 b8457f37-d9ea-0310-8a92-e5e31aec5664
add css main core

git-svn-id: https://plugins.svn.wordpress.org/yuzo-related-post/trunk@940612 b8457f37-d9ea-0310-8a92-e5e31aec5664