body {
  font-family: Arial, sans-serif;
  background: #f8f8fa;
  margin: 0;
  color: #222;
}
header {
  background: #2d3e50;
  color: #fff;
  padding: 1em 0;
  text-align: center;
}
nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5em;
}
nav a {
  color: #fff;
  text-decoration: none;
  margin: 0 0.2em;
  padding: 0 0.1em;
  border-radius: 4px;
  transition: background 0.2s;
  position: relative;
}
nav a:not(:last-child)::after {
  content: "";
  display: inline-block;
  position: absolute;
  right: -0.5em;
  top: 50%;
  transform: translateY(-50%);
  width: 1px;
  height: 1.2em;
  background: #fff;
  opacity: 0.5;
}
nav a:hover {
  text-decoration: underline;
  background: #1a2533;
}
main {
  max-width: 700px;
  margin: 2em auto;
  background: #fff;
  padding: 2em;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}
footer {
  text-align: center;
  padding: 1em 0;
  background: #eaeaea;
  color: #666;
  position: fixed;
  width: 100%;
  bottom: 0;
}
h1, h2, h3 {
  color: #2d3e50;
}
ul {
  padding-left: 1.5em;
}

@media (max-width: 600px) {
  main {
    max-width: 100%;
    margin: 1em;
    padding: 1em;
    border-radius: 0;
    box-shadow: none;
  }
  header {
    padding: 0.5em 0;
    margin-top: 0;
  }
  nav {
    flex-direction: row;
    flex-wrap: nowrap;
    gap: 0.25em;
    justify-content: center;
    width: 100vw;
    overflow-x: auto;
    white-space: nowrap;
    box-sizing: border-box;
    padding: 0 0.5em;
  }
  nav a {
    margin: 0.25em 0;
    padding: 0.5em;
    font-size: 1em;
    display: inline-block;
  }
  h1 {
    font-size: 1.5em;
  }
  h2 {
    font-size: 1.2em;
  }
  h3 {
    font-size: 1em;
  }
  ul, ol {
    padding-left: 1em;
    font-size: 1em;
  }
  img {
    max-width: 100%;
    height: auto;
  }
  section {
    padding: 0.5em 0;
  }
  body {
    font-size: 1em;
    padding: 0;
  }
  footer {
    position: static;
    padding: 0.5em 0;
    font-size: 0.9em;
  }
  h2 {
    font-size: 1.2em;
  }
  h3 {
    font-size: 1em;
  }
  footer {
    font-size: 0.9em;
    padding: 0.5em 0;
  }
}