body {
    font-family: Arial, sans-serif;
    background-color: #f2f2f2;
}

.container {
    width: 400px;
    margin: 40px auto;
    background: white;
    padding: 25px;
    border-radius: 8px;
}

h2 {
    text-align: center;
}

label {
    font-weight: bold;
    margin-top: 15px;
    display: block;
}

input {
    width: 100%;
    padding: 10px;
    margin-top: 5px;
    border: 2px solid red;
    border-radius: 5px;
}

input:valid {
    border-color: green;
}

button {
    margin-top: 20px;
    width: 100%;
    padding: 12px;
    background: black;
    color: white;
    border: none;
    font-size: 16px;
    border-radius: 6px;
    cursor: pointer;
}

button:hover {
    background: #333;
}