I use Ubuntu on my personal Computer that has a LAMP program running in it. LAMP is Linux, Apache, MySQL and PhpMyAdmin. It is sorta like having a personal web server inside of your computer. For me it works identical to my servers configured around the world that I work on. No need for a special server.
I have a friend who does it the same with his desktop version of FreeBSD and I am assuming MicroSoft has some version for windows also but that is beyond what I can help you with.
I have a copy of my server that I can make tests on, and if I crash the whole thing... ok, start over with my last good result. It also makes a nice offline backup copy... of sorts.
As to what you asked...
HTML Code:
<div id="imagecontainer" class="header-image-container" ...
This appears to be the background of where your header image is. You could add some css as to the background color attached to this id.
Something like:
HTML Code:
#imagecontainer { background-color: #FF0000; }
This might give you as start...