html {
  font-size: 16px;
}

body {
  font-family: 'Segoe UI', sans-serif;
  line-height: 1.6;
  background: #f9f9f9;
  color: #333;
  padding: 1rem;
  font-size: 1rem;
  box-sizing: border-box;
  margin: 0;
}

*, *::before, *::after {
  box-sizing: inherit;
  margin: 0;
  padding: 0;
}

header, footer {
  background-color: #eee;
  padding: 1rem;
  text-align: center;
}

nav ul {
  display: flex;
  flex-direction: column;
  align-items: center;
  list-style: none;
  gap: 0.5rem;
  margin: 1rem 0;
  padding: 0;
}

@media (min-width: 48rem) {
  nav ul {
    flex-direction: row;
    justify-content: center;
    gap: 1rem;
  }
}

nav a {
  text-decoration: none;
  color: #0066cc;
  font-weight: bold;
  font-size: 1rem;
}

nav a:hover,
nav a:focus {
  color: #ff6600;
  text-decoration: underline;
}

main {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  padding: 1rem;
  max-width: 80rem;
  margin: 0 auto;
}

section {
  background: #fff;
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: 0 0.125rem 0.375rem rgba(0,0,0,0.05);
}

@media (min-width: 48rem) {
  main {
    grid-template-columns: repeat(auto-fit, minmax(18.75rem, 1fr));
  }
}

@media (min-width: 100rem) {
  body {
    font-size: 1.1rem;
  }

  main {
    grid-template-columns: repeat(auto-fit, minmax(25rem, 1fr));
  }
}

h1, h2, h3 {
  color: #0066cc;
  margin-bottom: 0.5em;
  font-size: 1.5rem;
}

p, ul, li, a {
  font-size: 1rem;
  line-height: 1.5;
}

ul {
  padding-left: 1.5rem;
}

[tabindex]:focus,
a:focus {
  outline: 0.1875rem solid #ff6600;
  outline-offset: 0.25rem;
}