* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  color: #26323e;
  background: #ffffff;
}

header, main, footer {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

header {
  padding-top: 3.5rem;
}

h1 {
  margin: 0;
  font-size: 2rem;
  font-weight: 700;
  color: #1d2935;
  letter-spacing: 0.01em;
}

.subtitle {
  margin: 0.25rem 0 0;
  font-size: 1.125rem;
  color: #4a5a6a;
}

.tagline {
  margin: 1.25rem 0 0;
  color: #26323e;
}

nav {
  margin-top: 2rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid #d9dfe5;
}

nav a {
  margin-right: 1.5rem;
}

a {
  color: #24589c;
}

a:hover {
  color: #17406f;
}

h2 {
  margin: 0 0 1rem;
  font-size: 1.25rem;
  color: #1d2935;
}

section {
  margin-top: 2.75rem;
}

section + section {
  border-top: 1px solid #d9dfe5;
  padding-top: 2.75rem;
}

.timeline {
  list-style: none;
  margin: 0;
  padding: 0;
}

.timeline li {
  margin-bottom: 1rem;
}

strong {
  color: #1d2935;
}

footer {
  margin-top: 3.5rem;
  padding-top: 1.5rem;
  padding-bottom: 3rem;
  border-top: 1px solid #d9dfe5;
  color: #4a5a6a;
  font-size: 0.9375rem;
}

footer {
  max-width: 860px;
  margin-left: auto;
  margin-right: auto;
}

@media (max-width: 640px) {
  body {
    font-size: 1rem;
  }

  header {
    padding-top: 2rem;
  }

  h1 {
    font-size: 1.625rem;
  }

  nav a {
    display: inline-block;
    margin-right: 1rem;
    margin-bottom: 0.5rem;
  }

  section {
    margin-top: 2rem;
  }

  section + section {
    padding-top: 2rem;
  }
}