header, nav, article, aside, footer {
  border: 5px solid black;

}
header,article,footer{
  text-align: center;
}
.başlık{
 background-color: aqua;
}
nav
{
background-color: sandybrown;
}
.navbar{
  text-align: center;
  padding: 10px 0;

}
.navbar li{
display: inline-block;
margin: 0 20px;
}
.navbar a{
  text-decoration:none;
  color: aliceblue;
}
article
{
    height: 1500px ;
      flex: 2;
}
main {
  display: flex;
}
aside {
  flex: 1;
}