how i overrule list extent ability css

i have following impression an outmost css record called first.css

table { width: 100%; }

this creates tables fill container. there wholly twin little columns seem too distant any other.

to force columns seem nearer i have total style

table { width: 50%; }

to new record called second.css related html file.

is there any proceed overrule extent ability first.css but need mention extent second.css?

i html act there never extent property, nonetheless i wish cgange first.css