style.css not updating on Wordpress

Question

I've been struggling with this problem for days and can't find a solution.
I've been updating my css and the changes are not reflected for a crazy reason.
When I check the source, the style.css is this one, that is never updating :
http://www.dogecoin.link/wp-content/themes/directory/directory/style.css?1404006283
That is different from this one that is the good one and where the changes are reflected:
http://www.dogecoin.link/wp-content/themes/directory/directory/style.css
I don't know where the "style.css?1404006283" is cached and even after emptying the cache (W3 Cache) and waiting for 2days, the changes are not reflected.
Thank you for the help!

Answer 1

In your theme > style.css we have to add version as below

/*! 
    Theme Name: bestTheme,
    Version: 1.2
*/

initially style sheet will be loaded but "...style.css?ver=" will be null without version in styles sheet so changes will not effect. Changing the version number of stylesheet whenever you do a change to styles is a good practice and will have immediate effect on the production. Instead there will be no cache problem.