CSS errors

W3C Unicorn validator shows 2 errors in CSS file “plugins/events-manager/includes/css/events_manager.css”:
line 67
div.css-search div.em-search-main .em-search-submit:hover
Value Error : background (nullcolors.html#propdef-background) The first argument to the “linear-gradient” function should be “to top”, not “top” )
line 179
.em-bookings-table-overlay ul.em-bookings-cols-sortable li
Value Error : font-weight (nullfonts.html#propdef-font-weight) “none” is not a “font-weight” value : none
I am asking You to correct these errors.
Thank You