Redmine上の文書をまともに印刷できるようユーザーCSSを作りました ref: http://qiita.com/yuba/items/182174d51875d4a79c7a

file0.css

@media print {
  body {    
    font-family: serif;    
    font-size: 16px;    
    line-height: 1.6em;    
    color: #000;
  }
  ul,ol {    
    margin-bottom: 0 !important;
  }
  b, strong {    
    font-family: Meiryo;
  }
  a {    
    text-decoration: underline !important;    
    color: #000 !important;    
    background-color: #333;
  }
  h1, h2, h3, h4 {    
    font-family: Meiryo;    
    color: #000 !important;
  }
  h2, .wiki h1 {    
    font-size: 21px;
  }
  h3, .wiki h2 {    
    font-size: 19px;
  }
  h4, .wiki h3 {    
    font-size: 17px;
  }
  #main {    
    background: #fff;
  }
  div.wiki pre {    
    margin: 0.3em 1em 0.3em 1em;    
    white-space: pre-wrap;
    word-break: break-all;    
    font-size: 14px;    
    line-height: 1em;
  }
}