<div class="row">
  <div class="logo">Logo</div>
  <nav class="nav">Nav</nav>
  <nav class="user">User Menu</nav>
</div>

.row {
  display: flex;
  background: white;
  > * {
    padding: 2rem 1rem;
  }
}
.user {
  margin-left: auto;
}

body {
  margin: 1rem;
  background: #eee;
}