#cabecera {
  font-family: Arial,Helvetica,sans-serif;
  height: 80px;
  text-align: center;
  font-size: 20px;
  font-weight: bold;
  line-height: 20px;
  width: 100%;
  color: #333333;
  position: absolute;
  left: 0px;
  top: 0px;
  background-image: url(../imagenes/logos/logo.png);
  background-position:  center center;
  background-repeat: no-repeat;
  background-color: #333333;
  float: left;
}
#centro {
  border-style: none;
  width: 80%;
  font-family: Arial,Helvetica,sans-serif;
  font-weight: normal;
  font-style: normal;
  text-decoration: none;
  font-size: 15px;
  float: left;
  margin-top: 82px;
  position: relative;
  left: 0%;
  margin-left: 10%;
  top: 0px;
}