On-line calendar in PHP/Ajax/mySQL (similar to 30boxes.com)

All the pages comprising the project will be provided (in HTML format) along with the data structure, so the assignment is very clearly defined. In essence it will be something similar to [login to view URL] in functionality (where one can click on a date, a pop-up comes up allowing to create a new calendar entry comes up). There will be no sign-up related functionality, as this project is an add-on to an existing site. There is no sharing functionality nor themes, nor printing. Clean and simple code will be needed, so that everything is cross-browser compatible.