nav {
  float: left;
  width: 18%;
  background-color: white;
  margin-top: 1px;
  margin-right: 1px;
  margin-bottom: 1px;
  margin-left: 1px;
  border-radius: 5px;
}

article {
  width: 56%;
  float: left;
  background-color: silver;
  margin-top: 2px;
  margin-right: 2px;
  margin-bottom: 2px;
  margin-left: 2px;
  border-radius: 10px;
  font-family: Oswald;
  padding-top: 5px;
  padding-right: 5px;
  padding-bottom: 5px;
  padding-left: 5px;
}

aside {
  float: left;
  width: 18%;
  background-image: linear-gradient(180deg, #1e69de 0px, #1e69de 1%, #d5dde5 81%, #d5dde5 100%);
  margin-top: 1px;
  margin-right: 1px;
  margin-bottom: 1px;
  margin-left: 1px;
  border-radius: 30px;
}

footer {
  clear: both;
  text-align: center;
}

.cabecera {
  font-family: Roboto;
  font-size: 30px;
  background-color: #336666;
}

.videoyoutube {
  width: 50%;
  float: left;
}

.videos {
  text-align: center;
}

body {
  background-color: #33ccff;
}