body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: #f0f2f5;
    color: #333;
}
header {
    background: #1877f2;
    color: white;
    padding: 10px;
    display: flex;
    align-items: center;
}
header img {
    height: 40px;
    margin-right: 10px;
}
main {
    padding: 20px;
    text-align: center;
}
.btn {
    background-color: #1877f2;
    color: white;
    padding: 10px 20px;
    margin: 10px;
    text-decoration: none;
    display: inline-block;
}
form {
    background: white;
    max-width: 400px;
    margin: 20px auto;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
form input, form button {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
}