Lista de exercícios (aplicandos estilos diferentes)

Formal:

body {
    font-family: "Georgia", serif;
    background-color: #f4f4f4;
    color: #333;
    text-align: center;
    padding: 20px;
}
h1 {
    color: #2c3e50;
    font-size: 2em;
    font-weight: bold;
}
h2 {
    color: #34495e;
    font-size: 1.5em;
}
a {
    color: #2980b9;
    text-decoration: none;
    font-weight: bold;
}
footer {
    margin-top: 20px;
    font-style: italic;
}

Colorido:

body {
    font-family: "Comic Sans MS", cursive;
    background: linear-gradient(135deg, #ff9a9e, #fad0c4);
    color: #222;
    text-align: center;
    padding: 20px;
}
h1 {
    color: #e74c3c;
    font-size: 2.5em;
    text-shadow: 2px 2px #fff;
}
h2 {
    color: #27ae60;
    font-size: 1.8em;
}
a {
    background: #f39c12;
    color: #fff;
    padding: 10px 15px;
    border-radius: 5px;
    text-decoration: none;
    display: inline-block;
}
footer {
    background: #3498db;
    color: #fff;
    padding: 10px;
}

Minimalista:

body {
    font-family: "Arial", sans-serif;
    background-color: #fff;
    color: #000;
    text-align: center;
    padding: 20px;
    max-width: 800px;
    margin: auto;
}
h1 {
    font-size: 2em;
    font-weight: 600;
    margin-bottom: 10px;
}
h2 {
    font-size: 1.5em;
    color: #666;
}
a {
    color: #007BFF;
    text-decoration: none;
    border-bottom: 2px solid #007BFF;
}
footer {
    margin-top: 20px;
    font-size: 0.9em;
    color: #666;
}