Style Gutenberg metaboxes like they belong on the site

Bottom border (HR) can be removed using CSS:

#__BLOCK_ID__.postbox:not(.closed) .postbox-header{
    border-bottom: none;
}

p.s. change __BLOCK_ID__ to first parameter used in add_meta_box() function.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)