basic.css

main {
   max-width: 960px;
   margin: 1rem auto;
   padding: 1rem 2rem;
   font-size: 130%;
   line-height: 1.3;
}

header {
   background-color: seagreen;
   padding: 1rem;
   display: flex;
   justify-content: space-between;
   align-items: center;
}

header h1 {
   color: white;
   font-size: 200%;
}

nav {
   text-align: right;
}

nav ul {
   display: flex;
   text-align: center;
}

nav a {
   text-decoration: none;
   color: snow;
   margin: 0 1rem;
   padding: .5rem 1rem;
   border-radius: 1.5rem;
}

nav a:hover {
   background-color: #19462d;
}

/* ↓ Hides the checkbox in desktop mode ↓ */
nav input[type="checkbox"],
nav label {
   display: none;
}




/* ↓ Responsie Hamburger Mode ↓ */
@media (max-width: 600px) {

   /* ↓ Hides the links if the checkbox isn't clicked ↓ */
   input[type="checkbox"]:not(:checked)+ul {
      display: none;
   }


   /* ↓ The hamburger icon ↓ */
   header nav label {
      display: block;
      padding: 0.25em;
      align-self: center;
      color: white;
      font-size: 200%;
      background-color: #19462d;
   }

   /* Because we are in mobile mode, we want to display it as a vertical list */
   nav ul {
      background-color: #cacbca;
      flex-direction: column;
   }



   nav ul li {
      text-align: right;
      padding: 0;
      border-bottom: 3px solid silver;
   }

   nav ul li:last-child {
      border-bottom: none;
   }

   nav ul li a {
      display: block;
      font-size: 150%;
      color: black;
      margin: 0;
      border-radius: 0;
      padding: .5rem 2rem;
   }

   nav ul li a:hover {
      color: white;
   }
}