body {
  margin: 0;
  background-color: #222222;
  font-size: 20px;
  color: white;
  font-family: "Helvetica Neue", Helvetica, 'Open Sans', 'FreeSans', Arial, sans-serif;
}

#header h1 {
  font-size: 55px;
  font-weight: bold;
  padding: 0;
  margin: 0;
  color: #AAA;
  position: absolute;
  right: 0;
}

#header img {
  position: absolute;
  left: 0;
  height: 70px;
}

#header {
  width: 100%;
  position: relative;
  height: 70px;
}

#dashboard {
  position: relative;
  width: 100%;
}

#dashboard ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}

#dashboard ul li {
  margin: 0;
  padding: 5px 5px 0 0;
  width: 33%;
  height: 260px;
}

body {
  margin: 0;
  background-color: #222222;
  font-size: 20px;
  color: white;
  font-family: "Helvetica Neue", Helvetica, 'Open Sans', 'FreeSans', Arial, sans-serif;
}

#header h1 {
  font-size: 55px;
  font-weight: bold;
  padding: 0;
  margin: 0;
  color: #AAA;
  position: absolute;
  right: 0;
}

#header img {
  position: absolute;
  left: 0;
  height: 70px;
}

#header {
  width: 100%;
  position: relative;
  height: 70px;
}

#dashboard {
  position: relative;
  width: 100%;
}

#dashboard ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
}

#dashboard ul li {
  margin: 0 0 4px 0;
  padding: 0;
  width: 33%;
}

Remove right hand margin from CSS
Remove right hand margin from CSS
