*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html, body {
    height: 100%;
    overflow: hidden;
}

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: #0f172a;
    display: flex;
    align-items: center;
    justify-content: center;
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.btn-salvar {
    width: min(72vw, 280px);
    height: min(72vw, 280px);
    border: none;
    border-radius: 50%;
    background: linear-gradient(145deg, #3b82f6, #2563eb);
    color: #fff;
    font-size: clamp(1rem, 4.5vw, 1.25rem);
    font-weight: 700;
    line-height: 1.3;
    text-align: center;
    padding: 1.5rem;
    cursor: pointer;
    box-shadow:
        0 8px 32px rgba(37, 99, 235, 0.45),
        0 2px 8px rgba(0, 0, 0, 0.3);
    transition: transform 0.15s, box-shadow 0.15s, background 0.3s;
    user-select: none;
}

.btn-salvar:active:not(:disabled) {
    transform: scale(0.94);
    box-shadow:
        0 4px 16px rgba(37, 99, 235, 0.35),
        0 1px 4px rgba(0, 0, 0, 0.2);
}

.btn-salvar:disabled {
    opacity: 0.7;
    cursor: wait;
}

.btn-salvar.salvando {
    background: linear-gradient(145deg, #64748b, #475569);
}

.btn-salvar.salvo {
    background: linear-gradient(145deg, #22c55e, #16a34a);
    box-shadow:
        0 8px 32px rgba(34, 197, 94, 0.45),
        0 2px 8px rgba(0, 0, 0, 0.3);
}

.btn-salvar.erro {
    background: linear-gradient(145deg, #ef4444, #dc2626);
    box-shadow:
        0 8px 32px rgba(239, 68, 68, 0.4),
        0 2px 8px rgba(0, 0, 0, 0.3);
}