body {
  background-color: white;   /* page background */
  color: black;              /* text color */
  font-family: "Times New Roman", serif;
  margin: 0;
  padding: 0;
  text-align: center;
}

nav {
  background: black;         /* black nav bar */
  padding: 10px;
}

nav a {
  color: white;              /* white text links */
  text-decoration: none;
  margin: 0 10px;
}

.window {
  border: 2px solid black;
  background: white;         /* white window background */
  margin: 20px;
  display: inline-block;
  vertical-align: top;
  width: 250px;
}

.titlebar {
  background: black;         /* black title bar */
  color: white;              /* white text */
  padding: 5px;
  font-weight: bold;
  border-bottom: 2px solid black;
}

.content {
  padding: 10px;
}

.card-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

.card-grid a {
  margin: 10px;
  text-align: center;
  color: black;
  text-decoration: none;
}

.card-grid img {
  width: 80px;
  height: 80px;
  border: 2px solid black;
  display: block;
  margin: 0 auto 5px;
}