CSS from GitHub's doc views. Added html wrapper. Great for embedding in HTML documentation.

github-wikistyle.css

html{width: 85%; min-width: 600px;margin: 0 auto; font-family: sans-serif;}
h1,h2,h3,h4,h5,h6{border:0!important;}
h1{font-size:170%!important;border-top:4px solid #aaa!important;padding-top:.5em!important;margin-top:1.5em!important;}
h1:first-child{margin-top:0!important;padding-top:.25em!important;border-top:none!important;}
h2{font-size:150%!important;margin-top:1.5em!important;border-top:4px solid #e0e0e0!important;padding-top:.5em!important;}
h3{margin-top:1em!important;}
p{margin:1em 0!important;line-height:1.5em!important;}
ul{margin:1em 0 1em 2em!important;}
ol{margin:1em 0 1em 2em!important;}
ul ul, ul ol, ol ol, ol ul{margin-top:0!important;margin-bottom:0!important;}
blockquote{margin:1em 0!important;border-left:5px solid #ddd!important;padding-left:.6em!important;color:#555!important;}
dt{font-weight:bold!important;margin-left:1em!important;}
dd{margin-left:2em!important;margin-bottom:1em!important;}
table{margin:1em 0!important;}
table th{border-bottom:1px solid #bbb!important;padding:.2em 1em!important;}
table td{border-bottom:1px solid #ddd!important;padding:.2em 1em!important;}
pre{margin:1em 0!important;font-size:90%!important;background-color:#f8f8ff!important;border:1px solid #dedede!important;padding:.5em!important;line-height:1.5em!important;color:#444!important;overflow:auto!important;}
pre code{padding:0!important;font-size:100%!important;background-color:#f8f8ff!important;border:none!important;}
code{font-size:90%!important;background-color:#f8f8ff!important;color:#444!important;padding:0 .2em!important;border:1px solid #dedede!important;}