/**
* 文件名：loading.css
* 作用：铜鼓之声加载动画样式（成功案例标准版 - 轴心精准对齐 + 无限循环）
* 版本：14.0.0
* 设计标准：严格遵循成功案例的纯 rotateY 驱动、多页交错、静态遮蔽重置逻辑
*/

/* ===============================
 核心变量映射 (适配项目主题)
 =============================== */
:root {
  --book-bg: var(--bg-primary);
  --book-border: var(--border-color);
  --book-spine-width: 4px;
  --book-page-thickness: 1px;
  --book-shadow: rgba(0, 0, 0, 0.06);
  --book-shadow-hover: rgba(0, 0, 0, 0.12);
  --ease-page-flip: cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --book-bg: var(--bg-secondary);
  --book-border: var(--border-color);
  --book-shadow: rgba(0, 0, 0, 0.35);
  --book-shadow-hover: rgba(0, 0, 0, 0.55);
}

/* ===============================
 加载遮罩容器 (保留淡出逻辑与滚动锁定)
 =============================== */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: var(--book-bg);
  z-index: 99999;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 0.6s var(--ease-page-flip), visibility 0.6s var(--ease-page-flip);
  overflow: hidden;
  touch-action: none;
}

.loading-overlay.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

/* 滚动锁定 */
body.loading-active {
  overflow: hidden !important;
  touch-action: none;
  position: fixed;
  width: 100%;
  height: 100%;
}

/* ===============================
 3D 容器与呼吸微动
 =============================== */
.book-loader {
  position: relative;
  width: 64px;
  height: 84px;
  perspective: 1000px;
  transform-style: preserve-3d;
  animation: bookBreathe 3.5s var(--ease-page-flip) infinite;
  transform: translateZ(0);
}

/* ===============================
 书脊（含多层光泽扫描）
 =============================== */
.book-spine {
  position: absolute;
  left: 0;
  top: 0;
  width: var(--book-spine-width);
  height: 100%;
  background: linear-gradient(90deg,
    rgba(0, 0, 0, 0.08) 0%,
    rgba(0, 0, 0, 0.25) 35%,
    rgba(0, 0, 0, 0.4) 50%,
    rgba(0, 0, 0, 0.25) 65%,
    rgba(0, 0, 0, 0.08) 100%
  );
  border-radius: 2px 0 0 2px;
  transform: translateZ(0);
  z-index: 1;
  overflow: hidden;
  box-shadow: 1px 0 4px var(--book-shadow), inset 1px 0 2px rgba(0,0,0,0.02);
}

[data-theme="dark"] .book-spine {
  background: linear-gradient(90deg,
    rgba(255, 255, 255, 0.08) 0%,
    rgba(255, 255, 255, 0.25) 35%,
    rgba(255, 255, 255, 0.45) 50%,
    rgba(255, 255, 255, 0.25) 65%,
    rgba(255, 255, 255, 0.08) 100%
  );
}

.book-spine::after {
  content: '';
  position: absolute;
  top: 0; left: -100%;
  width: 50%; height: 100%;
  background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.5) 50%, transparent 100%);
  animation: spineGlowScan 2.4s var(--ease-page-flip) infinite;
}

.book-spine::before {
  content: '';
  position: absolute;
  top: 0; left: -50%;
  width: 30%; height: 100%;
  background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.25) 50%, transparent 100%);
  animation: spineGlowScanSec 2.4s var(--ease-page-flip) infinite;
  animation-delay: 0.3s;
}

/* ===============================
 页面基础样式（轴心精准对齐）
 =============================== */
.book-page {
  position: absolute;
  left: var(--book-spine-width);
  top: 0;
  width: calc(100% - var(--book-spine-width));
  height: 100%;
  background: var(--book-bg);
  border: var(--book-page-thickness) solid var(--book-border);
  border-radius: 0 8px 8px 0;
  /* 核心修复：严格锁定左侧中心为旋转轴 */
  transform-origin: 0% 50%;
  transform-style: preserve-3d;
  backface-visibility: visible;
  will-change: transform, box-shadow;
  transform: translateZ(0);
}

/* 页面背面材质 */
.book-page::after {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: linear-gradient(90deg,
    rgba(0, 0, 0, 0.06) 0%,
    rgba(0, 0, 0, 0.02) 25%,
    transparent 45%
  );
  border: var(--book-page-thickness) solid var(--book-border);
  border-radius: 8px 0 0 8px;
  transform: rotateY(180deg);
  backface-visibility: hidden;
  box-shadow: inset -3px 0 6px rgba(0,0,0,0.04);
}

[data-theme="dark"] .book-page::after {
  background: linear-gradient(90deg,
    rgba(255, 255, 255, 0.08) 0%,
    rgba(255, 255, 255, 0.03) 25%,
    transparent 45%
  );
}

/* 静态底页（增强层次与遮蔽重置瞬间） */
.book-page.static-left {
  z-index: 1;
  transform: rotateY(-180deg) translateZ(-1px);
  opacity: 0.92;
  box-shadow: inset -3px 0 10px rgba(0,0,0,0.06), -2px 2px 10px var(--book-shadow);
}

.book-page.static-right {
  z-index: 2;
  transform: rotateY(0deg) translateZ(-1px);
  opacity: 0.92;
  box-shadow: inset 3px 0 10px rgba(0,0,0,0.06), 2px 2px 10px var(--book-shadow);
}

/* ===============================
 循环动画核心（纯 rotateY 驱动）
 =============================== */
.book-page.active {
  z-index: 3;
  animation: pageFlipInfinite 2.4s var(--ease-page-flip) infinite;
}

/* 交错延迟：实现无缝连续翻动 */
.book-page.active:nth-of-type(3) { animation-delay: 0s; }
.book-page.active:nth-of-type(4) { animation-delay: 0.6s; }
.book-page.active:nth-of-type(5) { animation-delay: 1.2s; }
.book-page.active:nth-of-type(6) { animation-delay: 1.8s; }

@keyframes pageFlipInfinite {
  0% {
    transform: rotateY(0deg);
    box-shadow: inset 3px 0 8px rgba(0,0,0,0.04), 2px 2px 12px var(--book-shadow);
  }
  15% {
    transform: rotateY(-20deg);
    box-shadow: inset 3px 0 8px rgba(0,0,0,0.08), 8px 12px 24px var(--book-shadow-hover);
  }
  50% {
    transform: rotateY(-135deg);
    box-shadow: inset -3px 0 8px rgba(0,0,0,0.08), -8px 12px 24px var(--book-shadow-hover);
  }
  85% {
    transform: rotateY(-160deg);
    box-shadow: inset -3px 0 8px rgba(0,0,0,0.05), -4px 8px 16px var(--book-shadow);
  }
  100% {
    transform: rotateY(-180deg);
    box-shadow: inset -3px 0 8px rgba(0,0,0,0.04), -2px 2px 12px var(--book-shadow);
  }
}

@keyframes bookBreathe {
  0%, 100% { transform: translateZ(0) scale(1); }
  50% { transform: translateZ(0) scale(1.015); }
}

@keyframes spineGlowScan {
  0% { left: -100%; opacity: 0; }
  15% { opacity: 1; }
  50% { left: 200%; opacity: 1; }
  85% { opacity: 0; }
  100% { left: 200%; opacity: 0; }
}

@keyframes spineGlowScanSec {
  0% { left: -50%; opacity: 0; }
  20% { opacity: 0.5; }
  55% { left: 150%; opacity: 0.5; }
  90% { opacity: 0; }
  100% { left: 150%; opacity: 0; }
}

/* ===============================
 调试模式指示器
 =============================== */
.loading-debug-indicator {
  position: fixed;
  bottom: 20px;
  right: 20px;
  padding: 12px 20px;
  background: var(--accent-primary);
  color: var(--bg-primary);
  border-radius: 12px;
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
  z-index: 100000;
}

.loading-debug-indicator button {
  padding: 6px 14px;
  background: var(--bg-primary);
  color: var(--accent-primary);
  border: none;
  border-radius: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s var(--ease-page-flip);
}

.loading-debug-indicator button:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

/* ===============================
 移动端适配
 =============================== */
@media (max-width: 480px) {
  .book-loader { width: 52px; height: 68px; }
  .book-page { border-width: 0.8px; }
  .book-spine { width: 3px; }
  .loading-debug-indicator { bottom: 16px; right: 16px; padding: 10px 16px; font-size: 0.8rem; }
}

/* ===============================
 无障碍与性能降级
 =============================== */
@media (prefers-reduced-motion: reduce) {
  .book-loader, .book-page, .book-spine::after, .book-spine::before {
    animation: none !important;
    transform: none !important;
  }
  .book-page.static-left { transform: rotateY(-180deg) translateZ(-1px); }
  .book-page.static-right { transform: rotateY(0deg) translateZ(-1px); }
}