:root {
  --header-color: #fff;
  --header-text: #000
}

@media (prefers-color-scheme:dark) {
  :root {
    --header-color: #000;
    --header-text: #fff
  }
}

* {
  box-sizing: border-box
}

body {
  margin: 0;
  padding: 0;
  padding-top: 90px
}

header {
  padding: 30px 4% 10px;
  position: fixed;
  top: 0;
  width: 100%;
  background-color: var(--header-color);
  display: flex;
  align-items: center
}

h1 {
  margin: 0;
  padding: 0;
  font-size: 20px
}

a {
  text-decoration: none;
  color: var(--header-text)
}

nav {
  color: var(--header-text);
  margin: 0 0 0 auto
}

ul {
  list-style: none;
  margin: 0;
  display: flex
}

li {
  margin: 0 0 0 15px;
  font-size: 14px
}