/* ============================================
   BB绘本 — Claymorphism Design System
   风格：软萌黏土、圆润友好、适合儿童
   ============================================ */

/* Google Fonts: Fredoka (标题) + Nunito (正文) */
@import url('https://fonts.googleapis.com/css2?family=Fredoka:wght@400;500;600;700&family=Nunito:wght@300;400;500;600;700&display=swap');

/* ---------- Design Tokens ---------- */
:root {
  /* 柔和渐变背景色 */
  --bg-gradient-start: #FFF5F5;
  --bg-gradient-mid: #FFF0F5;
  --bg-gradient-end: #F0F4FF;

  /* 主色调 — 柔和暖粉 */
  --color-primary: #FF8BA7;
  --color-primary-light: #FFB3C6;
  --color-primary-dark: #E8728E;

  /* 辅助色 — 天空蓝 */
  --color-secondary: #7EC8E3;
  --color-secondary-light: #B5E2F4;

  /* 点缀色 — 柠檬黄 */
  --color-accent: #FFD166;
  --color-accent-light: #FFE4A0;

  /* 成功/标签色 — 薄荷绿 */
  --color-success: #7DD3A8;
  --color-success-light: #B5E8CB;

  /* 文字色 */
  --color-text: #4A4063;
  --color-text-light: #7B7394;
  --color-text-muted: #A8A1BE;

  /* 卡片色 */
  --color-card: rgba(255, 255, 255, 0.85);
  --color-card-border: rgba(255, 255, 255, 0.6);

  /* 阴影 — 黏土风格 */
  --shadow-soft: 4px 4px 12px rgba(174, 160, 200, 0.2),
                 -2px -2px 8px rgba(255, 255, 255, 0.8);
  --shadow-card: 6px 6px 16px rgba(174, 160, 200, 0.15),
                 -4px -4px 12px rgba(255, 255, 255, 0.9);
  --shadow-hover: 8px 8px 24px rgba(174, 160, 200, 0.25),
                  -6px -6px 16px rgba(255, 255, 255, 1);
  --shadow-inset: inset 2px 2px 6px rgba(174, 160, 200, 0.12),
                  inset -2px -2px 6px rgba(255, 255, 255, 0.7);

  /* 圆角 */
  --radius-sm: 12px;
  --radius-md: 20px;
  --radius-lg: 28px;
  --radius-xl: 36px;

  /* 字体 */
  --font-heading: 'Fredoka', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Nunito', 'PingFang SC', 'Microsoft YaHei', sans-serif;

  /* 间距 */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  background: linear-gradient(135deg, var(--bg-gradient-start) 0%, var(--bg-gradient-mid) 50%, var(--bg-gradient-end) 100%);
  min-height: 100vh;
  color: var(--color-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Header ---------- */
.site-header {
  text-align: left;
  padding: var(--space-lg) var(--space-xl) var(--space-md);
  position: relative;
  max-width: 1400px;
  margin: 0 auto;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

/* logo + 副标题左侧成组 */
.header-brand {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  flex-shrink: 0;
}

.logo {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-primary-dark);
  letter-spacing: -0.5px;
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  flex-shrink: 0;
  text-shadow: 0 2px 4px rgba(255, 139, 167, 0.15);
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--color-primary), var(--color-accent));
  border-radius: var(--radius-sm);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-soft);
  transition: transform 0.3s ease;
}

.logo:hover .logo-icon {
  transform: rotate(-5deg) scale(1.05);
}

.logo-icon svg {
  width: 24px;
  height: 24px;
  fill: white;
}

.subtitle {
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--color-text-light);
  margin: 0;
  padding-left: 2px;
  font-weight: 500;
  text-align: left;
  letter-spacing: 0.3px;
}

/* ---------- Month Navigation ---------- */
.month-nav {
  flex: 1;
  display: flex;
  justify-content: flex-end;
  gap: 6px;
  flex-wrap: nowrap;
  padding: 4px;
  background: rgba(255, 255, 255, 0.4);
  border-radius: 24px;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.5);
  box-shadow: var(--shadow-soft);
}

.month-btn {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 6px 14px;
  border-radius: 18px;
  border: none;
  background: transparent;
  color: var(--color-text-light);
  cursor: pointer;
  transition: all 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
  white-space: nowrap;
  flex: 0 0 auto;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.month-btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, var(--color-primary-light), var(--color-primary));
  opacity: 0;
  transition: opacity 0.25s ease;
  border-radius: 18px;
  z-index: -1;
}

.month-btn:hover::before {
  opacity: 0.15;
}

.month-btn:hover {
  color: var(--color-primary-dark);
  transform: translateY(-1px);
}

.month-btn.active {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: white;
  box-shadow: 3px 3px 10px rgba(255, 139, 167, 0.35),
              -2px -2px 6px rgba(255, 255, 255, 0.9);
  transform: translateY(-1px);
}

.month-btn.active:hover {
  transform: translateY(-2px);
  box-shadow: 4px 4px 12px rgba(255, 139, 167, 0.4),
              -2px -2px 8px rgba(255, 255, 255, 1);
}

/* Toast 提示 */
.toast {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(74, 64, 99, 0.95);
  color: white;
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.toast.show {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- Book Grid ---------- */
.book-grid {
  max-width: 1400px;
  margin: 0 auto;
  padding: var(--space-lg) var(--space-lg) var(--space-2xl);
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-xl);
}

/* ---------- Book Card — Claymorphism ---------- */
.book-card {
  background: var(--color-card);
  border: 2px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  transition: transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1),
              box-shadow 0.3s ease;
  cursor: pointer;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  position: relative;
}

.book-card-number {
  position: absolute;
  top: 10px;
  left: 10px;
  min-width: 44px;
  height: 32px;
  padding: 0 10px;
  background: linear-gradient(135deg, var(--color-accent-light), var(--color-accent));
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-heading);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-text);
  box-shadow: 3px 3px 8px rgba(255, 209, 102, 0.4),
              -2px -2px 6px rgba(255, 255, 255, 0.8);
  z-index: 10;
  border: 2px solid rgba(255, 255, 255, 0.6);
}

.book-card-number .ordinal-num {
  letter-spacing: -0.3px;
}

.book-card:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: var(--shadow-hover);
}

.book-card:active {
  transform: translateY(-2px) scale(0.98);
  box-shadow: var(--shadow-soft);
}

.book-cover {
  width: 100%;
  height: 300px;
  object-fit: cover;
  display: block;
  border-bottom: 2px solid rgba(255, 255, 255, 0.4);
}

.book-info {
  padding: var(--space-lg);
}

.book-title {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
  line-height: 1.3;
}

.book-title-cn {
  font-size: 0.95rem;
  color: var(--color-text-light);
  margin-bottom: var(--space-md);
  font-weight: 400;
}

.book-meta {
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.tag {
  background: linear-gradient(135deg, var(--color-secondary-light), var(--color-secondary));
  color: white;
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  box-shadow: 2px 2px 6px rgba(126, 200, 227, 0.3);
}

.level {
  background: linear-gradient(135deg, var(--color-accent-light), var(--color-accent));
  color: var(--color-text);
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 700;
  box-shadow: 2px 2px 6px rgba(255, 209, 102, 0.3);
}

/* ---------- Footer ---------- */
footer {
  text-align: center;
  padding: var(--space-xl) var(--space-lg);
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
}

/* ---------- Empty State ---------- */
.empty-state {
  grid-column: 1 / -1;
  text-align: center;
  padding: var(--space-2xl) var(--space-lg);
}

.empty-state h2 {
  font-family: var(--font-heading);
  font-size: 2rem;
  color: var(--color-text-light);
  margin-bottom: var(--space-sm);
}

.empty-state p {
  color: var(--color-text-muted);
}

/* ---------- Animations ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .site-header {
    padding: var(--space-md) var(--space-md) var(--space-sm);
  }

  .header-content {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-sm);
  }

  .month-nav {
    flex-wrap: wrap;
    width: 100%;
  }

  .month-btn {
    flex: 0 0 calc(25% - 6px);
  }

  .logo {
    font-size: 1.6rem;
  }

  .book-grid {
    grid-template-columns: 1fr;
    padding: var(--space-md);
    gap: var(--space-lg);
  }

  .book-cover {
    height: 240px;
  }
}

@media (max-width: 375px) {
  .logo {
    font-size: 1.4rem;
  }

  .book-cover {
    height: 200px;
  }
}