* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: Arial, sans-serif;
  background-color: #f6fff8;
  color: #222;
  line-height: 1.6;
}


header {
  background-color: darkgreen;
  color: white;
  text-align: center;
  padding: 25px 10px;
}
header h1 {
  font-size: 2em;
  margin-bottom: 10px;
}
header a {
  color: lightgreen;
  text-decoration: none;
}
header a:hover {
  text-decoration: underline;
}


nav {
  background-color: green;
  text-align: center;
  padding: 10px 0;
}
nav ul {
  list-style: none;
}
nav li {
  display: inline-block;
  margin: 0 10px;
}
nav a {
  color: white;
  text-decoration: none;
  font-weight: bold;
}
nav a:hover {
  text-decoration: underline;
}


main {
  background-color: white;
  max-width: 900px;
  margin: 20px auto;
  padding: 20px;
  border: 1px solid lightgreen;
  border-radius: 5px;
}

h2 {
  color: darkgreen;
  border-bottom: 1px solid green;
  padding-bottom: 5px;
  margin-bottom: 10px;
  font-size: 1.3em;
}

article {
  border-left: 3px solid lightgreen;
  padding-left: 10px;
  margin-bottom: 10px;
  background-color: #f9fff9;
}

ul {
  padding-left: 20px;
}

footer {
  background-color: darkgreen;
  color: white;
  text-align: center;
  padding: 15px;
  font-size: 0.9em;
  margin-top: 20px;
}
footer a {
  color: lightgreen;
  text-decoration: none;
}
footer a:hover {
  text-decoration: underline;
}



/* Tablet view (width ≤ 991px) */
@media (max-width: 991px) {
  main {
    width: 90%;
    padding: 15px;
  }

  nav li {
    margin: 5px;
  }
}

/* Mobile view (width ≤ 767px) */
@media (max-width: 767px) {
  header h1 {
    font-size: 1.6em;
  }

  nav ul {
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  nav li {
    display: block;
    margin: 8px 0;
  }

  main {
    width: 95%;
    margin: 15px auto;
    padding: 10px;
  }

  h2 {
    font-size: 1.1em;
  }

  footer {
    font-size: 0.8em;
    padding: 10px;
  }
}