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

header {
  width: 100%;
  background-color: #f5f5f5;
  background-position: center;
  background-size: cover;
}

nav {
  width: 100%;
  padding: 20px 0;
  text-align: center;
}

.logo {
  white-space: nowrap;
  margin: 0 auto 20px auto;
  cursor: pointer;
  font-size: 3rem;
  font-weight: 450;
}

nav ul {
  background: #000;}

nav ul li {
  display: inline-block;
  list-style:n none;
  margin: 20px 30px;
}

nav ul li a {
  text-decoration: none;
  color: white;
}

#main {
  margin: 0 10px 10px 10px;
  display: flex;
}

#content {
  width: 468px;
  margin: 0 10px;
  order: 2;
}

#submenu {
  width: 160px;
  order: 1;
}

#topic {
  width: 250px;
  order: 3;
}