/* ============================================================
   左下角导航 (assets/side-nav.css)
   - 固定左下角，垂直排列 4 个导航按钮 + 文字
   - hover 过渡效果（平滑放大/高亮）
   ============================================================ */

.side-nav {
  position: fixed;
  left: 20px;
  bottom: 56px; /* 在底部页脚上方 */
  z-index: 60;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.side-item {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 7px 14px;
  border-radius: 9999px;
  background: rgba(0, 0, 0, 0.38);
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: rgba(255, 255, 255, 0.68);
  text-decoration: none;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: color 320ms cubic-bezier(0.4, 0, 0.2, 1),
              background 320ms cubic-bezier(0.4, 0, 0.2, 1),
              border-color 320ms cubic-bezier(0.4, 0, 0.2, 1),
              transform 320ms cubic-bezier(0.4, 0, 0.2, 1);
  width: fit-content;
  animation: sideItemIn 450ms cubic-bezier(0.4, 0, 0.2, 1) backwards;
}
.side-item:nth-child(2) { animation-delay: 70ms; }
.side-item:nth-child(3) { animation-delay: 140ms; }
.side-item:nth-child(4) { animation-delay: 210ms; }

@keyframes sideItemIn {
  from { opacity: 0; transform: translateX(-14px); }
  to   { opacity: 1; transform: translateX(0); }
}

.side-item:hover {
  color: #fff;
  background: rgba(0, 0, 0, 0.6);
  border-color: rgba(255, 255, 255, 0.32);
  transform: translateX(6px);
}

.side-item .side-dot {
  width: 7px;
  height: 7px;
  border-radius: 9999px;
  background: rgba(255, 255, 255, 0.35);
  flex-shrink: 0;
  transition: background 200ms ease, transform 200ms ease;
}
.side-item:hover .side-dot {
  background: #fff;
  transform: scale(1.3);
}

.side-item.is-active {
  color: #fff;
  border-color: rgba(255, 255, 255, 0.32);
}
.side-item.is-active .side-dot {
  background: #fff;
  transform: scale(1.3);
}

.side-label {
  font-size: 0.8rem;
  font-weight: 400;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

@media (max-width: 640px) {
  .side-nav {
    left: 12px;
    bottom: 48px;
    gap: 6px;
  }
  .side-item { padding: 5px 11px; }
  .side-label { font-size: 0.74rem; }
}