plugin messes up the site

what is this?????

wp-content/plugins/netbase-widgets-for-siteorigin/assets/nbt-so-style.min.css?ver=1.0

this style messes up the whole site design…

it is very non-standard way of design. you should bind all your styles within specific class, i.e.:

.nbt_block .soemthing{}

and all your blocks should have .nbt_block class…