/* 回到顶部按钮 - 简约图标版 */
.back-to-top-btn {
    position: fixed;
    top: 80px;
    right: 24px;
    width: 36px;
    height: 36px;
    background: transparent;
    border: none;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    z-index: 9999;
    opacity: 0;
    transform: translateX(20px);
    transition: all 0.3s cubic-bezier(0.22, 1, 0.36, 1);
    pointer-events: none;
    padding: 0;
}

.back-to-top-btn.show {
    opacity: 0.7;
    transform: translateX(0);
    pointer-events: auto;
}

.back-to-top-btn:hover {
    opacity: 1;
    transform: scale(1.1);
}

.back-to-top-btn:active {
    transform: scale(0.95);
}

.back-to-top-btn svg {
    width: 100%;
    height: 100%;
    color: var(--accent-color);
    transition: all 0.3s ease;
}

/* 移动端适配 */
@media (max-width: 768px) {
    .back-to-top-btn {
        top: 70px;
        right: 16px;
        width: 32px;
        height: 32px;
    }
}