A more readable Jira - This is an extremly raw stylesheet

style.css

@import url(http://fonts.googleapis.com/css?family=Roboto);
@import url(http://fonts.googleapis.com/css?family=Merriweather);
@import url(http://fonts.googleapis.com/css?family=Inconsolata);

body {
  /* Improve legibility */
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.mod-header {
background: none !important;
}

  h1, h2, h3, h4, h5, h6 {
  color: #000;
    font-family: 'Roboto', sans-serif;
    font-weight: normal !important;
  }
 
h1 {font-size: 2em !important;}  
h2 {font-size: 1.8em !important;}
h3 {font-size: 1.5em !important;}
h4 {font-size: 1.2em !important;}
h5 {font-size: 1em !important;}
h6 {font-size: 0.8em !important;}

.activity-comment {
	padding-top: 2.5em;
  padding-bottom: 2.5em;
}

.issue-data-block {
	border: none;
}

.action-head {
  font-family: 'Roboto', sans-serif;
  font-size: 1.5em;
  margin-bottom: 1.5em;
}

.aui-avatar img {
  height: 1em;
  width: 1em;
}

a.user-hover.user-avatar{
padding: 2px 0 2px 1.2em;
}

.action-body {
  font-size: 1.1em;
  font-family: 'Merriweather', serif;
  line-height: 1.5;
}
  
.action-body tt,
.action-body pre {
  background-color: #f5f5f5;
  font-family: 'Inconsolata', monospace ;
  font-size: 1.1em;
}