* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

body {
    min-height: 100vh;
    background: linear-gradient(135deg, #1d2671, #c33764);
    display: flex;
    align-items: center;
    justify-content: center;
}

.container {
    background: #ffffff;
    width: 100%;
    max-width: 420px;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
}

h1 {
    text-align: center;
    margin-bottom: 25px;
    color: #333;
}

.form-group {
    margin-bottom: 18px;
}

label {
    display: block;
    margin-bottom: 6px;
    font-weight: bold;
    color: #444;
}

input {
    width: 100%;
    padding: 10px;
    border-radius: 6px;
    border: 2px solid #ccc;
    font-size: 14px;
    transition: border-color 0.3s;
}

/* ❌ Invalid input → RED */
input:invalid {
    border-color: #e74c3c;
}

/* ✅ Valid input → GREEN */
input:valid {
    border-color: #2ecc71;
}

button {
    width: 100%;
    padding: 12px;
    background: #1d2671;
    color: #fff;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s;
}

button:hover {
    background: #c33764;
}