:root {
    --kb-fab-bg: rgba(255, 255, 255, 0.92);
    --kb-fab-color: #14161a;
    --kb-fab-border: rgba(0, 0, 0, 0.10);
    --kb-fab-shadow: 0 10px 30px rgba(0, 0, 0, 0.14);
    --kb-fab-hover-shadow: 0 14px 36px rgba(0, 0, 0, 0.18);
}

[data-theme="dark"] {
    --kb-fab-bg: rgba(27, 31, 36, 0.92);
    --kb-fab-color: rgba(255, 255, 255, 0.92);
    --kb-fab-border: rgba(255, 255, 255, 0.10);
    --kb-fab-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
    --kb-fab-hover-shadow: 0 14px 36px rgba(0, 0, 0, 0.45);
}

.kb-theme-fab {
    position: fixed;
    right: 20px;
    bottom: 20px;
    z-index: 1085;
    width: 54px;
    height: 54px;
    border: 1px solid var(--kb-fab-border);
    border-radius: 999px;
    background: var(--kb-fab-bg);
    color: var(--kb-fab-color);
    backdrop-filter: saturate(180%) blur(12px);
    -webkit-backdrop-filter: saturate(180%) blur(12px);
    box-shadow: var(--kb-fab-shadow);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: transform .18s ease, box-shadow .18s ease, background-color .18s ease, color .18s ease, border-color .18s ease;
}

    .kb-theme-fab:hover {
        transform: translateY(-2px);
        box-shadow: var(--kb-fab-hover-shadow);
    }

    .kb-theme-fab:active {
        transform: translateY(0);
    }

    .kb-theme-fab:focus-visible {
        outline: none;
        box-shadow: 0 0 0 4px rgba(13, 110, 253, 0.18), var(--kb-fab-hover-shadow);
    }

    .kb-theme-fab i {
        position: absolute;
        font-size: 1.1rem;
        transition: opacity .18s ease, transform .18s ease;
    }

/* Light mode: mostra luna */
[data-theme="light"] .kb-theme-icon-dark,
:root .kb-theme-icon-dark {
    opacity: 1;
    transform: scale(1);
}

[data-theme="light"] .kb-theme-icon-light,
:root .kb-theme-icon-light {
    opacity: 0;
    transform: scale(.7);
}

/* Dark mode: mostra sole */
[data-theme="dark"] .kb-theme-icon-dark {
    opacity: 0;
    transform: scale(.7);
}

[data-theme="dark"] .kb-theme-icon-light {
    opacity: 1;
    transform: scale(1);
}

@media (max-width: 576px) {
    .kb-theme-fab {
        right: 16px;
        bottom: 16px;
        width: 50px;
        height: 50px;
    }
}