body {
    font-family: Arial;
    background: #f4f4f4;
    text-align: center;
}

form {
    margin: 20px;
}

input, select, button {
    padding: 10px;
    margin: 5px;
}

#activity-list {
    margin-top: 20px;
}

.card {
    background: white;
    margin: 10px auto;
    padding: 10px;
    width: 300px;
    border-radius: 8px;
    box-shadow: 0 0 5px gray;
}