Hello,
Please make sure that you never update the Default style.css File and instead use css/custom.css File for your Custom CSS Codes. Check more about this here: http://docs.semicolonweb.com/docs/getting-started/theme-customization/ .
Also Color Schemes can be changed very easily without you needing to edit the style.css File and explained here: http://docs.semicolonweb.com/docs/getting-started/color-schemes/ .
Also, this Color Scheme codes are already present in this Template. So simply find the following code:
<link rel="stylesheet" href="css/colors.php?color=DE6262" type="text/css" />
and replace the DE6262 HEX Value with 07073E.
This will definitely work fine. Consider checking out the Documentations for more helpful setup guides. Hope this Helps!
Let us know if we can help you with anything else or if you find any further issues.