.botao-topo {
    position: fixed;
    right: 20px;
    bottom: 20px;
    z-index: 999;
    display: none;
    padding: 0.8rem 1rem;
    border: 1px solid color-mix(in srgb, var(--op-btn-hover-bg, #1d4ed8) 32%, var(--op-border, #dbe3ef));
    background: color-mix(in srgb, var(--op-btn-bg, #ffffff) 82%, transparent);
    color: var(--op-btn-text, #111);
    box-shadow: 0 10px 24px rgba(15, 23, 42, 0.16);
    cursor: pointer;
    font: inherit;
}

.botao-topo.visivel {
    display: block;
}

html[data-theme='escuro'] .botao-topo {
    border-color: color-mix(in srgb, var(--op-btn-hover-bg, #ffffff) 45%, var(--op-border, #334155));
    background: color-mix(in srgb, var(--op-btn-hover-bg, #ffffff) 78%, transparent);
    color: var(--op-btn-hover-text, #0f172a);
    box-shadow: 0 12px 28px rgba(0, 0, 0, 0.34);
}