* {
  box-sizing: border-box;
}

body {
  background-color: #e5e5e5;
  color: #000;
  font-family: "Times New Roman", Times, serif;
  margin: 0;
}

/* Links */
a {
  color: darkgreen;
  text-decoration: none;
}

a:hover {
  color: blue;
}

/* Grey highlight section */
.highlight {
  background-color: #444444;
  color: #fff;
  padding: 20px;
  border-radius: 10px;
}

.highlight a {
  color: lightgreen;
}

.highlight a:hover {
  color: white;
}

hr {
  border: none;
  height: 1px;
  background-color: #444;
}

.main-content {
  max-width: 780px;
  margin: 2em auto;
  padding: 1.5em;
  background-color: #ffffff;
  box-shadow: 0 0 0 1px #ddd;
}

footer {
  text-align: center;
  padding: 20px;
}

img {
  max-width: 100%;
  height: auto;
}

/* Mobile tweaks */
@media (max-width: 600px) {
  .main-content {
    padding: 1em;
    margin: 1em;
  }

  .highlight {
    padding: 15px;
  }

  body {
    font-size: 16px;
  }
}