body {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 20px;
}

h1 {
    text-align: center;
}

form {
    display: flex;
    flex-direction: column;
    max-width: 300px;
}

input {
    margin-bottom: 5px;
    padding: 5px;
}

input.invalid {
    border: 2px solid red;
}

p {
    color: red;
    margin: 0 0 10px 0;
}

.hidden {
    display: none;
}

button {
    padding: 5px;
}