rename to _const.less & _macro.less since they are more fundamental
shrink the space of footer by setting the copyright to margin 0
finish the basic template of web page with a nav
made a beautiful nav bar~
add a search textbox in nav, but cannot respond to it yet
add a 404 page for all invalid urls
decrease the notfound page's paper block's width
move some handlers to pages package; now it can click on nav sidebar (but there is a bug -- a black line?)
let jinja_env be retrieved by a function in utils
move 404 page handler to pages package
add a 'me' module in pages package