* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    background: linear-gradient(135deg, #0f172a, #1e293b);
    font-family: Arial, sans-serif;

    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    background: #ffffff;
    width: 100%;
    max-width: 380px;
    padding: 25px;
    border-radius: 14px;
    text-align: center;
    box-shadow: 0 20px 40px rgba(0,0,0,0.2);
}

h1 {
    margin-bottom: 10px;
    font-size: 1.6rem;
}

#message {
    font-size: 0.9rem;
    color: #475569;
    margin-bottom: 12px;
}

input {
    width: 100%;
    padding: 14px;
    font-size: 1rem;
    border-radius: 8px;
    border: 1px solid #cbd5f5;
    margin-bottom: 12px;
}

button {
    width: 100%;
    padding: 14px;
    font-size: 1rem;
    background: #2563eb;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

button:hover {
    background: #1e40af;
}

#qrBox {
    margin-top: 18px;
}

#qrImage {
    width: 200px;
    max-width: 100%;
}

/*  Mobile (small phones) */
@media (max-width: 360px) {
    h1 {
        font-size: 1.3rem;
    }

    input, button {
        padding: 12px;
        font-size: 0.95rem;
    }

    #qrImage {
        width: 160px;
    }
}

/*  Tablet */
@media (min-width: 600px) {
    .container {
        max-width: 420px;
    }
}

/*  Laptop & Desktop */
@media (min-width: 1024px) {
    .container {
        max-width: 460px;
        padding: 30px;
    }

    h1 {
        font-size: 1.8rem;
    }
}