body, html {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  font-family:"Calibri", sans-serif;
}

header {
  text-align: center;
}

nav {
  display: flex;
  justify-content: center;
}

.nav-btn {
  background-color: grey;
  border: none;
  color: white;
  padding: 20px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 4px 2px;
  border-radius: 30%;
}

.content {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
}

.title{
  font-size: 24px;
  font-weight: bold;
}