i'm currently working on a web portal solution. I'm thinking to use CSS3 and HTML5 with javascript frameworks to make web portal responsive and especially in response time with data collecting from database.

if i have almost a clear vision how web portal should look like for users, i have some questions about the administrative panel/side.

I see a lot of web portal like http://freelancer.com or http://www.monster.com using only html, javascript framework and css.
I guess they didn't chose a market CMS (like joomla, wordpress, ...) due to customization issues and maybe to make it more secure somehow.
However, i was wondering where could i find nice example of administrative panel design that i could use or be inspired of to create my own for my web portal ?
Moreover, i should use PHP for server side script and datacollecting... however, is there a template style or javascript framework to use to make webportal more professional and flexible ?