Here is how the site looks like for me:
But I think I know why is this happening. I have noticed that when you check the site from other browsers (where the site is not showing up as it should), you are not logged in to WordPress Dashboard. Try to log in to your site from one of those other web browsers, and I bet that the site will look like fine. :-)
Now, here is the trick: I have checked your site's source code, and it suggests that you have some kind of caching plugin installed. Those plugins work in a way that they make a sort of snapshot of every page of your site, and if a visitor comes, the plugin shows the visitor that snapshot, because it is faster. Depending on your settings, those snapshots can be pretty old, in some cases even a day old. Those plugins recreate those snapshots (the cache) when you are modifying something to the page's content. They have no way telling that you are changing the theme's css rules, thus, they are not showing the actual state of the site. The trick with the login is: usually most caching plugins are set up so if someone has login access to the site, than that person must be someone important, so no matter what, he should get the most up to date data from the site, so for the logged in users there is no caching going on. The other reason is, while your site could have 1000 or even more visitors (who are not logged in), usually there is a little amount of users with login privileges, so it is not noticable if the cache is not applied to them.
My advice is, it is completely unnecessary to use a caching plugin until you have that amount of visitors that your site is getting slow. And for the time period when you tweaking something to your site, it is the best to turn off caching for everyone, because this way you can ensure that in every second you are seeing the actual and real state of the site.
So deactivate the caching plugin, or click on recreate/rebuild cache.
Let me know if that solved the problem.