/* 左侧贴边可滑出的目录导航 */
.side-nav {
  position: fixed;
  top: 50%;
  left: 0;
  transform: translateY(-50%) translateX(calc(-100% + 34px));
  z-index: 400;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 14px 14px 16px;
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-radius: 0 16px 16px 0;
  box-shadow: var(--card-shadow);
  transition: transform 0.4s cubic-bezier(0.645, 0.045, 0.355, 1);
}

.side-nav:hover,
.side-nav:focus-within,
.side-nav.open {
  transform: translateY(-50%) translateX(0);
}

.side-nav-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 160px;
}

.side-nav-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 2px;
  color: var(--text-muted);
  opacity: 0.7;
  padding: 4px 12px 8px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 9px 12px;
  border: none;
  border-radius: 10px;
  background: transparent;
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  text-align: left;
  white-space: nowrap;
  transition: all 0.25s ease;
}

.nav-item:hover {
  background: var(--btn-bg);
  color: var(--text-strong);
}

.nav-item.active {
  background: var(--accent);
  color: #fff;
}

.nav-item.active .nav-dot {
  background: #fff;
}

.nav-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
  transition: background 0.25s ease;
}

.nav-name {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  max-width: 168px;
}

.nav-item:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.side-nav-grip {
  width: 8px;
  height: 44px;
  border-radius: 4px;
  background: var(--indicator);
  flex-shrink: 0;
  cursor: pointer;
  transition: background 0.3s ease;
}

.side-nav:hover .side-nav-grip {
  background: var(--accent);
}

/* 右侧贴边可滑出的工具面板 */
.side-panel {
  position: fixed;
  top: 50%;
  right: 0;
  transform: translateY(-50%) translateX(calc(100% - 34px));
  z-index: 400;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-radius: 16px 0 0 16px;
  box-shadow: var(--card-shadow);
  transition: transform 0.4s cubic-bezier(0.645, 0.045, 0.355, 1);
}

.side-panel:hover,
.side-panel:focus-within,
.side-panel.open {
  transform: translateY(-50%) translateX(0);
}

.panel-grip {
  width: 8px;
  height: 44px;
  border-radius: 4px;
  background: var(--indicator);
  flex-shrink: 0;
  cursor: pointer;
  transition: background 0.3s ease;
}

.side-panel:hover .panel-grip {
  background: var(--accent);
}

.panel-buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
  align-items: center;
}

.panel-btn {
  width: 42px;
  height: 42px;
  border: none;
  border-radius: 12px;
  background: var(--btn-bg);
  color: var(--btn-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  padding: 0;
}

.panel-btn:hover {
  background: var(--accent);
  color: #fff;
  transform: translateY(-2px);
}

.panel-btn svg {
  width: 21px;
  height: 21px;
}

.panel-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* 设置弹层 */
.settings-popover {
  position: fixed;
  right: 96px;
  top: 50%;
  transform: translateY(-50%);
  width: 264px;
  padding: 18px;
  background: var(--card-bg);
  border-radius: 16px;
  box-shadow: var(--card-shadow-hover);
  z-index: 401;
  color: var(--text-strong);
  font-size: 14px;
  animation: popIn 0.25s ease;
}

.settings-popover[hidden] {
  display: none;
}

.settings-popover h4 {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 16px;
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.setting-row:last-child {
  margin-bottom: 0;
}

.setting-row > span {
  color: var(--text-muted);
}

/* 开关 */
.toggle {
  position: relative;
  width: 42px;
  height: 24px;
  border-radius: 12px;
  background: var(--indicator);
  cursor: pointer;
  transition: background 0.3s ease;
  border: none;
  padding: 0;
  flex-shrink: 0;
}

.toggle::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  transition: transform 0.3s ease;
}

.toggle.on {
  background: var(--accent);
}

.toggle.on::after {
  transform: translateX(18px);
}

/* 播放速度 */
.speed-group {
  display: flex;
  gap: 6px;
}

.speed-group button {
  border: none;
  background: var(--btn-bg);
  color: var(--btn-color);
  padding: 5px 12px;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.25s ease;
}

.speed-group button.active {
  background: var(--accent);
  color: #fff;
}

.speed-group button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

/* 动画模式 */
.anim-group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: flex-end;
  max-width: 158px;
}

.anim-group button {
  border: none;
  background: var(--btn-bg);
  color: var(--btn-color);
  padding: 5px 10px;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.25s ease;
}

.anim-group button.active {
  background: var(--accent);
  color: #fff;
}

.anim-group button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

@keyframes popIn {
  from {
    opacity: 0;
    transform: translateY(-50%) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(-50%) scale(1);
  }
}

@media screen and (max-width: 768px) {
  .settings-popover {
    right: 60px;
  }

  /* 移动端禁用 backdrop-filter，降低 GPU 开销 */
  .side-nav,
  .side-panel {
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
    background: var(--card-bg);
  }
}