nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: 0.6s;
  padding: 40px 100px;
  z-index: 600;
}

nav.onscroll {
  padding: 5px 100px;
  background: rgba(0, 0, 0, 0.5);
}

nav .logo {
  position: relative;
  font-weight: 700;
  color: #fff;
  text-decoration: none;
  font-size: 2em;
  text-transform: uppercase;
  letter-spacing: 2px;
}

nav ul {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

nav ul li {
  position: relative;
  list-style: none;
}

nav ul li a {
  position: relative;
  margin: 0 15px;
  text-decoration: none;
  color: #fff;
  letter-spacing: 2px;
  font-weight: 500px;
  transition: 0.6s;
}
nav.onscroll .logo,
nav.onscroll ul li a {
  color: #fff;
}