CSS overhaul for 2 page task site

This is a web app built with Codeigniter that logs tasks in projects. Each project has it's own unique page, and each task does too - with the ability to add comments and files.

It's a simple interface - I will supply the URL by private message, although I have included screenshots below. It has AJAX functionality, with "click to edit" fields" This needs to be maintained.

The basic functionality is working, but it needs a cosmetic makeover. This is where you come in! I have provided mockups of the makeover I would like, although I am open to suggestions.

There is also three new functions to add: due date for each task (with calendar), sorting tasks and comments, and moving tasks up and down in the list.

At the end of the job, I would like to know where I can edit CSS and layout/text if needed. I am aware of the CodeIgniter folder structure, and am very strong on HTML design.

Note: I have taken styling inspiration from rranks.com and taskk.it. I would like to use the font from rranks.com, whatever it is! I also like the simplicity of rranks.com so any suggestions on how to look more like that is welcomed.

Screenshots supplied and available here: http://imgur.com/a/kSGNO

Includes Current Project Page, Current Task Page, Mockup of New Project Page, Mockup of New Task Page, rranks.com screenshot, taskk.it screenshot