positioning.css

/*limited reset*/
html, body, div, section, article, aside, header, hgroup, footer, nav, h1, h2, h3, h4, h5, h6, p, blockquote, address, time, span, em, strong, img, ol, ul, li, figure, canvas, video, th, td, tr {
  margin: 0;
  padding: 0;
  border: 0;
  vertical-align:baseline;
}

/*html5 display rule*/
address, article, aside, canvas, details, figcaption, figure, footer, header, hgroup, nav, menu, nav, section, summary {
  display: block;
}

/* general styles */
body {
  font-family: Georgia, sans-serif;
  font-size: 96%;
}
ul {
  list-style-type: none;
}
img {
  border: 1px solid red;
}
/* header and main nav styles */
header {
  position: fixed;
  background-color: lightgrey;
  width: 100%;
  top: 0;
  left: 0;
  padding: 10px 20px;
}
header ul {
  background-color: crimson;
  text-align: center;
}
header li {
  padding: 10px;
  display: inline-block;
}
header a:link, 
header a:visited,
header a:hover
header a:active {
  color: white;
}

/* content wrapper */
#wrapper {
  overflow:auto;
  width: 960px;
  margin: 120px auto 0;
  padding: 10px 20px;
}

/* left nav column */
section:first-child {
  padding: 10px;
  float:left;
  width: 186px;
}

/* The main section */
section + section {
  width: 520px;
  border: 1px solid darkgrey;
  padding: 0 16px;
  float:left;
}
section + section h2 {
  padding:10px;
  margin:0 -16px;
  color:white;
  background-color: lightgrey;  
}
/* Article elements only appear in main section */
article {
  clear: both;
}
article h3 {
  padding-bottom:10px;
  margin:24px 0;
  color:grey;
  border-bottom: 2px dashed darkgrey;
}
article p {
  margin-bottom: 20px;
}
/* Images in first paragraph of article float left, otherwise right */
article p:first-of-type img {
  float: left;
  margin: 0 10px 10px 0;
}
article img {
  float: right;
  margin: 0 0 10px 10px;
}

/* right column */
aside {
  padding: 10px;
  margin-left: 20px;
  width: 160px;
  float:right;
  background-color: lightblue;
}
aside h2, aside li {
  margin-bottom: 24px;
}

footer {
  margin-top: 24px;
  padding: 10px;
  text-align: center;
}