/* FAB - Floating Action Button */
.fab {
    position: fixed;
    z-index: 9999;
    right: 1rem;
    bottom: 5rem;
    transition: opacity 0.3s ease;
}

/* モバイル: 既存固定バー(3.75rem)のすぐ上に配置 */
@media only screen and (max-width: 768.9999px) {
    .fab {
        bottom: 4.5rem;
    }

    /* return_topをFABの上に移動 */
    #return_top {
        bottom: 9rem !important;
    }
}

/* デスクトップ: return_topと横にずらして配置 */
@media only screen and (min-width: 769px) {
    .fab {
        bottom: 2rem;
        right: 6rem;
    }
}

.fab__btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 3.5rem;
    height: 3.5rem;
    border-radius: 50%;
    background: #06C755;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    cursor: pointer;
    text-decoration: none;
}

.fab__btn:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.3);
}

.fab__btn:active {
    transform: scale(0.95);
}

.fab__icon {
    width: 2rem;
    height: 2rem;
}