My CSS code is not centering my footer. I can't work out why :(

GENERAL
*********************************************/

#wrapper {
  max-width: 940px;
  margin: 0 auto;
  padding: 0 5%;
}

a {
   text-decoration: none;
}

body {
   font-family: 'Open Sans', sans-serif;
}



/*********************************************
HEADING
*********************************************/

#logo {
   text-align: center;
   margin: 0;
}

h1 {
  font-family: 'Changa One', cursive;
  margin: 15px 0;
  font-size: 1.75em;
  font-weight: normal;
  line-height: 0.8em;
}

h2 {
  font-size: 0.75em;
  margin: -5px 0 0;
  font-weight: normal;
}



/*********************************************
NAVIGATION
*********************************************/

nav {
  text-align: center;
  padding: 10px 0;
  margin: 20px 0 0;
}



/*********************************************
FOOTER
*********************************************/

footer {
  font-size: 0.75em;
  text-align: centre;
  padding-top: 50px;
  color: #ccc;
}

/*********************************************
COLOURS
*********************************************/



/* site body */
body {
  background-color: #fff;
  color: #999;
}

/* purple header */
header {
background: #bc82ba;
border-color: #a564a3;
}

/* nav background on mobile devices */
nav {
  background: #a564a3;
}

/* logo text */
h1, h2 {
color: #fff;
}

/* link colour*/
a {
color: #bc82ba;
}



/* nav link */
nav a,  nav a:visited {
  color: #fff;
}

/* selected nav link */
nav a.selected, nav a:hover {
color: #61255f;
}