* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --primary: #4f6ef7;
  --primary-dark: #3b5bdb;
  --primary-light: #eef1ff;
  --primary-bg: #eef1ff;
  --bg: #f5f6fa;
  --sidebar-bg: #ffffff;
  --sidebar-text: #1a2332;
  --sidebar-sub: #8e98a8;
  --sidebar-border: #eaedf2;
  --sidebar-hover: #f4f6fb;
  --sidebar-active-bg: #eef1ff;
  --sidebar-active-border: #4f6ef7;
  --card-bg: #ffffff;
  --text: #1a2332;
  --text-light: #6b7688;
  --border: #eaedf2;
  --accent: #22c55e;
  --tag-bg: #eef1ff;
  --tag-color: #4f6ef7;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans SC', 'PingFang SC', sans-serif;
  color: var(--text);
  background: var(--bg);
  height: 100vh;
  overflow: hidden;
}

#app {
  display: flex;
  height: 100vh;
}

/* ============ 侧边栏 ============ */
#sidebar {
  width: 280px;
  min-width: 280px;
  background: #fff;
  border-right: 1px solid var(--sidebar-border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: 1px 0 8px rgba(0,0,0,0.03);
}

.sidebar-header {
  padding: 20px 16px 16px;
  border-bottom: 1px solid var(--sidebar-border);
  background: linear-gradient(135deg, #fafbff 0%, #fff 100%);
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 14px;
}

.sidebar-logo-img {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  object-fit: cover;
  box-shadow: 0 2px 6px rgba(79,110,247,0.2);
}

.sidebar-logo-text h2 {
  font-size: 1.15em;
  font-weight: 700;
  color: var(--sidebar-text);
  line-height: 1.2;
}

.sidebar-logo-text .sidebar-subtitle {
  font-size: 0.78em;
  color: var(--sidebar-sub);
  margin-top: 2px;
  font-weight: 400;
}

.word-list-sidebar {
  flex: 1;
  overflow-y: auto;
  padding: 0;
}

.word-list-sidebar::-webkit-scrollbar {
  width: 3px;
}

.word-list-sidebar::-webkit-scrollbar-thumb {
  background: #d0d5e0;
  border-radius: 2px;
}

.word-list-sidebar .loading {
  text-align: center;
  padding: 40px 20px;
  color: var(--sidebar-sub);
  font-size: 0.9em;
}

/* 月份组 - 折叠 */
.month-group {
  border-bottom: 1px solid #f0f2f5;
}

.month-group:last-child {
  border-bottom: none;
}

.month-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px 12px 20px;
  cursor: pointer;
  font-size: 0.82em;
  font-weight: 700;
  color: #566573;
  letter-spacing: 0.03em;
  user-select: none;
  transition: all 0.15s;
  position: relative;
}

.month-header::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 20px;
  right: 16px;
  height: 1px;
  background: var(--sidebar-border);
  opacity: 0.6;
}

.month-header:hover {
  background: #f7f8fc;
  color: var(--primary);
}

.month-header .month-left {
  display: flex;
  align-items: center;
  gap: 8px;
}

.month-header .month-count {
  font-weight: 500;
  color: #b0b8c8;
  font-size: 0.85em;
  background: #f0f2f5;
  padding: 0 7px;
  border-radius: 8px;
  line-height: 1.6;
}

.month-toggle {
  font-size: 0.55em;
  color: #c0c8d8;
  transition: transform 0.2s;
  display: inline-block;
  width: 16px;
  height: 16px;
  line-height: 16px;
  text-align: center;
  background: #f0f2f5;
  border-radius: 4px;
}

.month-toggle.collapsed {
  transform: rotate(-90deg);
}

.month-items {
  overflow: hidden;
  transition: max-height 0.25s ease;
}

.month-items.collapsed {
  max-height: 0 !important;
}

/* 侧边栏日期项 */
.sidebar-item {
  display: flex;
  align-items: center;
  padding: 10px 16px 10px 28px;
  cursor: pointer;
  transition: all 0.15s;
}

.sidebar-item:hover {
  background: var(--sidebar-hover);
}

.sidebar-item.active {
  background: linear-gradient(90deg, var(--sidebar-active-bg) 0%, #fff 100%);
  position: relative;
}

.sidebar-item.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 6px;
  bottom: 6px;
  width: 3px;
  background: var(--sidebar-active-border);
  border-radius: 0 3px 3px 0;
}

.sidebar-item .date-badge {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--primary-light);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-right: 12px;
  transition: all 0.2s;
}

.sidebar-item.active .date-badge {
  background: linear-gradient(135deg, var(--primary) 0%, #6c5ce7 100%);
  color: #fff;
  box-shadow: 0 2px 8px rgba(79,110,247,0.25);
}

.sidebar-item .date-badge .month {
  font-size: 0.55em;
  color: var(--primary);
  line-height: 1;
  font-weight: 600;
}

.sidebar-item.active .date-badge .month {
  color: rgba(255,255,255,0.85);
}

.sidebar-item .date-badge .day {
  font-size: 1em;
  font-weight: 700;
  line-height: 1.2;
}

.sidebar-item .item-info {
  flex: 1;
  min-width: 0;
}

.sidebar-item .item-title {
  font-size: 0.88em;
  font-weight: 600;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--sidebar-text);
  transition: color 0.15s;
}

.sidebar-item.active .item-title {
  color: var(--primary-dark);
}

.sidebar-item .item-meta {
  font-size: 0.72em;
  color: #b0b8c8;
  margin-top: 2px;
}

/* ============ Hero 头部（背景图 + 信息叠加） ============ */
.detail-hero {
  margin: 0 0 28px;
  border-radius: 14px;
  overflow: hidden;
}

.hero-bg {
  position: relative;
  min-height: 320px;
  display: flex;
  align-items: flex-end;
  padding: 60px 48px 40px;
  background-size: cover;
  background-position: center;
  background-color: var(--primary);
  overflow: hidden;
}

/* 16:9 背景图宽高比 */
.hero-bg::before {
  content: '';
  display: block;
  padding-top: 56.25%; /* 9/16 = 56.25% */
}

.hero-bg:not([style*="background-image"])::before {
  padding-top: 30%;
}

.hero-bg {
  min-height: 0;
  padding: 0;
}

.hero-overlay,
.hero-content {
  position: absolute;
  left: 0;
  right: 0;
}

.hero-overlay {
  inset: 0;
  background: linear-gradient(to top, rgba(0,0,0,0.75) 0%, rgba(0,0,0,0.35) 50%, rgba(0,0,0,0.1) 100%);
}

.hero-content {
  bottom: 0;
  padding: 40px 48px;
  z-index: 1;
  color: #fff;
  width: 100%;
}

/* 无背景图时用固定高度 */
.hero-bg:not([style*="background-image"]) {
  min-height: 260px;
  padding: 60px 48px 40px;
  display: flex;
}

.hero-bg:not([style*="background-image"])::before {
  display: none;
}

.hero-bg:not([style*="background-image"]) .hero-overlay {
  display: none;
}

.hero-bg:not([style*="background-image"]) .hero-content {
  position: relative;
  padding: 0;
}

.hero-top {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.hero-emoji {
  font-size: 1.5em;
  line-height: 1;
}

.hero-seq {
  font-size: 0.82em;
  background: rgba(255,255,255,0.18);
  padding: 2px 10px;
  border-radius: 10px;
  font-weight: 500;
}

.hero-title {
  font-size: 2em;
  font-weight: 700;
  margin-bottom: 10px;
  line-height: 1.3;
  text-shadow: 0 1px 3px rgba(0,0,0,0.3);
}

.hero-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  flex-wrap: wrap;
}

.hero-item {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 6px;
  font-size: 0.8em;
  font-weight: 500;
}

.hero-category {
  background: rgba(139, 92, 246, 0.55);
  color: #ede9fe;
}

.hero-createdate {
  background: rgba(20, 184, 166, 0.55);
  color: #ccfbf1;
}

.hero-idium {
  font-size: 0.95em;
  font-style: italic;
  margin-bottom: 12px;
  padding: 4px 12px;
  border-radius: 8px;
  background: rgba(245, 158, 11, 0.35);
  color: #fef3c7;
  display: inline-block;
  text-shadow: 0 1px 1px rgba(0,0,0,0.2);
}

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: 4px;
}

.hero-tag-blue {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(59, 130, 246, 0.6);
  color: #dbeafe;
}

.hero-tag-green {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(34, 197, 94, 0.6);
  color: #dcfce7;
}

.hero-tag-purple {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(139, 92, 246, 0.6);
  color: #ede9fe;
}

.hero-tag-orange {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(245, 158, 11, 0.6);
  color: #fef3c7;
}

.hero-tag-pink {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(236, 72, 153, 0.6);
  color: #fce7f3;
}

.hero-tag-teal {
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75em;
  font-weight: 500;
  background: rgba(20, 184, 166, 0.6);
  color: #ccfbf1;
}

/* ============ 主内容区 ============ */
#content {
  flex: 1;
  overflow-y: auto;
  padding: 36px 48px;
  background: var(--bg);
  max-width: 1024px;
  margin: 0 auto;
}

/* 无侧边栏时内容区居中 */
@media (min-width: 1324px) {
  #content {
    padding: 36px 48px 36px 36px;
  }
}

#content::-webkit-scrollbar {
  width: 6px;
}

#content::-webkit-scrollbar-thumb {
  background: #d0d5e0;
  border-radius: 3px;
}

/* 欢迎页面 */
.welcome {
  text-align: center;
  padding: 120px 20px;
}

.welcome-icon {
  font-size: 3.6em;
  margin-bottom: 16px;
}

.welcome h1 {
  font-size: 1.8em;
  margin-bottom: 10px;
  color: var(--text);
  font-weight: 700;
}

.welcome p {
  color: var(--text-light);
  font-size: 1em;
}

.welcome-hint {
  margin-top: 14px;
  font-size: 0.85em !important;
  color: #b0b8c8 !important;
}

/* 单词卡片 */
.word-card {
  background: var(--card-bg);
  border-radius: 14px;
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--sidebar-border);
  transition: box-shadow 0.2s;
}

.word-card:hover {
  box-shadow: var(--shadow-md);
}

.word-card .word-header {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin-bottom: 6px;
}

.word-card .word-number {
  font-size: 0.82em;
  color: var(--primary);
  font-weight: 600;
  min-width: 24px;
}

.word-card .word-text {
  font-size: 1.4em;
  font-weight: 700;
  color: var(--primary-dark);
}

.word-card .word-phonetic {
  font-size: 0.95em;
  color: var(--sidebar-sub);
  font-weight: 400;
}

.word-card .word-pos {
  font-size: 0.88em;
  color: var(--text-light);
  margin-bottom: 12px;
}

.word-card .word-pos .pos {
  color: var(--accent);
  font-weight: 600;
}

.word-card .word-example {
  background: var(--primary-light);
  border-radius: 10px;
  padding: 14px 16px;
  margin-bottom: 10px;
}

.word-card .word-example .sentence-en {
  color: var(--text);
  margin-bottom: 5px;
  line-height: 1.6;
  font-size: 0.95em;
}

.word-card .word-example .sentence-zh {
  color: var(--text-light);
  font-size: 0.88em;
}

.word-card .word-tip {
  font-size: 0.85em;
  color: var(--text-light);
  padding: 10px 14px;
  background: #fffbeb;
  border-radius: 8px;
  border-left: 3px solid #f6c23e;
}

.word-card .word-tip::before {
  content: '💡 ';
}

/* ============ 响应式 ============ */
@media (max-width: 768px) {
  #sidebar {
    width: 100%;
    min-width: 100%;
    max-height: 45vh;
  }

  #app {
    flex-direction: column;
  }

  #content {
    padding: 20px;
  }

  .detail-hero {
    margin: 0 0 20px;
    border-radius: 10px;
  }

  .hero-content {
    padding: 24px 20px;
  }

  .hero-title {
    font-size: 1.5em;
  }
}