* {
  box-sizing: border-box;
  padding: 0;
  margin: 0;
}

body {
  background-color: steelblue;
  font-family: "Open Sans", sans-serif;
  font-size: 16px;
  height: 100vh;

  display: grid;
  grid-template-areas:
    " header header header"
    " nav content sidebar"
    "nav footer footer";
  grid-template-columns: 1fr 4fr 1fr;
  grid-template-rows: 80px 1fr 70px;
}

header,
footer,
main,
aside,
nav {
  background-color: steelblue;
  color: #fff;
  padding: 20px;
  border: skyblue 1px solid;
}

header {
  grid-area: header;
}
header a:link {
  text-decoration: none;
}

header a:visited {
  text-decoration: none;
}

header a:hover {
  text-decoration: none;
}

header a:active {
  text-decoration: none;
}
footer {
  grid-area: footer;
}

main {
  grid-area: content;
  text-align: center;
}

aside {
  grid-area: sidebar;
}

nav {
  grid-area: nav;
}

iframe {
  border-radius: 5px;
}
header h1 {
  display: inline;
}
iframe {
  visibility: hidden;
}