* {
    box-sizing: border-box;
    font-family: 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
}

body {
    margin: 0;
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea, #764ba2);
    display: flex;
    align-items: center;
    justify-content: center;
}

.card {
    background: #ffffff;
    width: 100%;
    max-width: 380px;
    padding: 32px;
    border-radius: 18px;
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.25);
}

h1 {
    margin: 0 0 24px;
    text-align: center;
    font-size: 26px;
    color: #111827;
}

.field {
    margin-bottom: 18px;
}

label {
    display: block;
    margin-bottom: 6px;
    font-size: 14px;
    font-weight: 600;
    color: #374151;
}

input, select {
    width: 100%;
    padding: 14px 16px;
    font-size: 16px;
    border-radius: 12px;
    border: 1px solid #d1d5db;
    outline: none;
    transition: border-color 0.2s, box-shadow 0.2s;
}

input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.25);
}

button {
    width: 100%;
    margin-top: 10px;
    padding: 14px;
    font-size: 16px;
    font-weight: 700;
    border: none;
    border-radius: 14px;
    cursor: pointer;
    color: #ffffff;
    background: linear-gradient(135deg, #7290ff, #764ba2);
    transition: transform 0.15s ease, box-shadow 0.15s ease;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 24px rgba(0,0,0,0.25);
}

#wynik {
    margin-top: 22px;
    padding: 14px;
    border-radius: 12px;
    text-align: center;
    font-size: 18px;
    font-weight: 600;
}

.low {
    background: #e0f2fe;
    color: #0369a1;
}

.normal {
    background: #dcfce7;
    color: #166534;
}

.over {
    background: #fef3c7;
    color: #92400e;
}

.obese {
    background: #fee2e2;
    color: #991b1b;
}

.error {
    background: #f3f4f6;
    color: #374151;
}

@media (max-width: 480px) {
    .card {
        border-radius: 0;
        min-height: 100vh;
        max-width: 100%;
        box-shadow: none;
        padding: 24px;
    }

    h1 {
        font-size: 24px;
    }

    input, select,
    button {
        font-size: 18px;
        padding: 16px;
    }
}