/* ============================================================
   flip.css - 翻页动画
   ============================================================ */

.page {
  position: relative;
}

/* 翻页进入动画：从右侧翻入 */
.page.active {
  animation: flipIn 0.45s cubic-bezier(0.4, 0, 0.2, 1);
  transform-origin: left center;
}

@keyframes flipIn {
  0% {
    opacity: 0;
    transform: perspective(800px) rotateY(-25deg) translateX(20px);
    box-shadow: -10px 0 20px rgba(0,0,0,0.1);
  }
  60% {
    opacity: 1;
    transform: perspective(800px) rotateY(8deg) translateX(0);
  }
  100% {
    opacity: 1;
    transform: perspective(800px) rotateY(0) translateX(0);
    box-shadow: none;
  }
}

/* 反向翻页（向左翻） */
.page.flip-back.active {
  animation: flipBack 0.45s cubic-bezier(0.4, 0, 0.2, 1);
}
@keyframes flipBack {
  0% {
    opacity: 0;
    transform: perspective(800px) rotateY(25deg) translateX(-20px);
  }
  60% {
    opacity: 1;
    transform: perspective(800px) rotateY(-8deg) translateX(0);
  }
  100% {
    opacity: 1;
    transform: perspective(800px) rotateY(0) translateX(0);
  }
}

/* 书页边缘装饰 */
.book-wrap {
  position: relative;
}
.book-wrap::before,
.book-wrap::after {
  content: "";
  position: absolute;
  top: 0; bottom: 0;
  width: 8px;
  pointer-events: none;
  z-index: 1;
}
.book-wrap::before {
  left: 0;
  background: linear-gradient(90deg, rgba(0,0,0,0.06), transparent);
}
.book-wrap::after {
  right: 0;
  background: linear-gradient(-90deg, rgba(0,0,0,0.04), transparent);
}

/* Tab 切换时的下划线滑动 */
.tabs {
  position: relative;
}
.tab-indicator {
  position: absolute;
  bottom: -2px;
  height: 3px;
  background: var(--pink);
  border-radius: 2px;
  transition: left 0.3s cubic-bezier(0.4, 0, 0.2, 1), width 0.3s;
}