body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
  }

ul.undecorated {
    list-style-type: none;
}

nav {
    background-color: #333;
    padding: 1rem 0;
}

nav ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
}

nav li {
    margin: 0 1rem;
}

nav a {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: background-color 0.3s;
}

nav a:hover {
    background-color: #555;
}

.container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 2rem;
    background-color: white;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

* Dashed border */
hr.dashed {
  border-top: 3px dashed #bbb;
}

/* Dotted border */
hr.dotted {
  border-top: 3px dotted #bbb;
}

/* Solid border */
hr.solid {
  border-top: 3px solid #bbb;
}

/* Rounded border */
hr.rounded {
  border-top: 8px solid #bbb;
  border-radius: 5px;
}