/* ============================================================
 * 右下角浮动按钮：返回顶部 + 打赏
 * 页面出现滚动条时才显示，缓慢淡入淡出
 * ============================================================ */

/* 容器 */
.float-btn-group {
    position: fixed;
    right: 22px;
    bottom: 22px;
    z-index: 9998;
    display: flex;
    flex-direction: column;
    gap: 12px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: opacity .5s ease, transform .5s ease, visibility .5s;
}
.float-btn-group.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

/* 单个按钮通用 */
.float-btn {
    width: 46px;
    height: 46px;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    color: #fff;
    box-shadow: 0 4px 14px rgba(0,0,0,.18);
    transition: transform .25s ease, box-shadow .25s ease, opacity .25s;
    outline: none;
}
.float-btn:hover {
    transform: scale(1.08);
    box-shadow: 0 6px 20px rgba(0,0,0,.25);
}
.float-btn:active { transform: scale(.96); }

/* 返回顶部 */
.float-btn.top {
    background: linear-gradient(135deg, #555, #333);
}
.float-btn.top:hover { background: linear-gradient(135deg, #666, #444); }

/* 打赏 */
.float-btn.dashang {
    background: linear-gradient(135deg, #FF6B35, #FF8C42);
    animation: pulse 2.4s ease-in-out infinite;
}
.float-btn.dashang:hover { background: linear-gradient(135deg, #FF7A45, #FF9B52); }

@keyframes pulse {
    0%,100% { box-shadow: 0 4px 14px rgba(255,107,53,.35); }
    50%     { box-shadow: 0 4px 22px rgba(255,107,53,.65); }
}

/* 返回顶部：滚动进度环（可选装饰） */
.float-btn.top .arrow-up {
    display: inline-block;
    transition: transform .3s;
}
.float-btn.top:hover .arrow-up { transform: translateY(-2px); }

/* 移动端稍微小一点 */
@media (max-width: 640px) {
    .float-btn-group { right: 14px; bottom: 14px; gap: 10px; }
    .float-btn { width: 42px; height: 42px; font-size: 18px; }
}