joomla ja_purity template get rid of #ja-wrapper min-width

I'm using the ja_purity template in Joomla on one our sites and it's been mentioned by those with big screens ( rich gits, lol! ) that there's too much white space. So what I need to do is limit the size the page displays at. Which I've used this css

#ja-wrapper {
max-width: 1200px ;
min-width: 800px ;
}

and put it into template.css in the css folder. IT DIDNT WORK THOUGH.

as it was being overrun by
#ja-wrapper {
max-width: 100% ;
}

which apparently was being generated on line 50 of the index.php of the template. Which I couldn't find !
Theres an easy way to fix this though and thats to use !important after the css I've added. This tells the system to override other css.

#ja-wrapper {
max-width: 1200px !important;
min-width: 800px !important;
}