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

body {
    background: linear-gradient(135deg, #0f172a, #1e293b);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.card {
    background: #ffffff;
    width: 100%;
    max-width: 420px;
    padding: 32px 24px;
    border-radius: 16px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
    text-align: center;
}

.card h1 {
    font-size: 24px;
    margin-bottom: 8px;
    color: #0f172a;
}

.card p.subtitle {
    font-size: 14px;
    color: #64748b;
    margin-bottom: 24px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

input[type="text"] {
    padding: 12px;
    border-radius: 8px;
    border: 1px solid #cbd5e1;
    font-size: 14px;
    outline: none;
    transition: 0.2s ease;
}

input[type="text"]:focus {
    border-color: #2563eb;
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

input[type="button"] {
    padding: 12px;
    border-radius: 8px;
    border: none;
    background-color: #2563eb;
    color: white;
    font-weight: 600;
    cursor: pointer;
    transition: 0.2s ease;
}

input[type="button"]:hover {
    background-color: #1d4ed8;
}

#res {
    margin-top: 20px;
    font-size: 14px;
    color: #334155;
}

#res strong {
    color: #2563eb;
}