A neater way to solve the problem isn't to try and override the styles; it's to work out why those styles are there in the first place.
I've had a very quick poke around the theme and I can see that the dynamic stylesheet is generating its styles based on theme settings; the theme should have an extra options screen in the admin area where you can enter your own width for content.
Failing that you can comment out line 619 from 'functions.php' which currently reads "add_action( 'wp_enqueue_scripts', 'bitLumen_enqueue_dynamic', 10 );"
That's the line that loads up the dynamic stylesheet
I'd recommend you try and find the settings in the admin area first; no sense trying to brute force your styles with !important rules
#content > * {max-width: 100%;}- Miljan Puzović