:root {
  --main-bg: #0b270b;
  --main-text: white;
}

body {
  background-color: var(--main-bg); /* dark green */
  color: var(--main-text);
}

nav {
  display: inline-block;   /* makes width hug content */
  border: 1px solid var(--main-text); /* add your border style */
  padding: 10px;           /* some spacing inside */
}


nav a {
  color: white;
  text-decoration: none;
  display: block;
  margin: 0.25em 0;
}