/* ==========================================================================
   Design Tokens & CSS Variables (Scholarly Light Theme)
   ========================================================================== */
:root {
  --bg-page: #F5F3ED;          /* 略微偏深的温润纸张底色，增加卡片对比 */
  --card-bg: #FAF9F5;          /* 霞鹜文楷推荐纸张色 */
  --highlight-bg-color: #E4ECF5;/* 淡蓝色高亮底色 */
  --brand-color: #1B365D;      /* 儒雅古典深蓝色 */
  --text-main: #3D3D3A;        /* 柔和深碳色，利于长时间阅读 */
  --text-heading: #141413;     /* 亮黑色 */
  
  --border-color: rgba(27, 54, 93, 0.1);
  --border-active: rgba(27, 54, 93, 0.25);
  
  /* Scholarly Accents for Entity Types */
  --color-type-person: #A06A3B;   /* 琥珀褐 (人物) */
  --color-type-group: #1B365D;    /* 雅深蓝 (集团) */
  --color-type-location: #3A6351; /* 黛绿 (地理) */
  --color-type-system: #6D4C41;   /* 赭石 (制度) */
  --color-type-event: #B53333;    /* 朱砂红 (事件) */

  /* UI Dimensions */
  --header-height: 56px;
  --main-font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --safe-area-bottom: env(safe-area-inset-bottom, 0px);
}

/* ==========================================================================
   Reset & Base Styles
   ========================================================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--main-font);
  background-color: var(--bg-page);
  color: var(--text-main);
  height: 100vh;
  height: 100dvh;
  overflow: hidden;
  position: relative;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

/* ==========================================================================
   App Shell Layout
   ========================================================================== */
#app-container {
  display: flex;
  flex-direction: column;
  height: 100%;
  position: relative;
}

.app-header {
  height: var(--header-height);
  background: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  z-index: 10;
  flex-shrink: 0;
  box-shadow: 0 1px 4px rgba(27, 54, 93, 0.04);
}

.header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.app-logo-text {
  font-family: var(--main-font);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: 1px;
  color: var(--brand-color);
}

.icon-btn {
  background: transparent;
  border: none;
  color: var(--brand-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 6px;
  border-radius: 4px;
  transition: background 0.2s;
}

.icon-btn:active {
  background: var(--highlight-bg-color);
}

.header-mode-indicator {
  font-size: 0.78rem;
  color: var(--brand-color);
  background: var(--highlight-bg-color);
  padding: 2px 10px;
  border-radius: 12px;
  font-weight: 500;
}

/* ==========================================================================
   Viewport Scroll Container (50% Snap Scroll)
   ========================================================================== */
.scroll-container {
  flex: 1;
  overflow-y: scroll;
  -webkit-overflow-scrolling: touch;
  display: flex;
  flex-direction: column;
  position: relative;
  background-color: var(--bg-page);
}

.snap-scroll {
  scroll-snap-type: y mandatory;
}

/* ==========================================================================
   Entity Card Layout (50% of Viewport Scroll Height)
   ========================================================================== */
.relation-card {
  scroll-snap-align: start;
  flex: 0 0 50%;
  height: 50%;
  width: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 24px 20px;
  text-align: center;
  position: relative;
  background-color: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
  transition: background-color 0.2s;
}

/* Top card indicator for snap centering styling */
.relation-card.is-top {
  background-color: var(--card-bg);
}

/* Bottom card is active choice panel */
.relation-card.is-bottom {
  background-color: #FAF9F5;
}

/* Entity Typography */
.entity-type {
  font-size: 0.72rem;
  letter-spacing: 1px;
  padding: 1px 6px;
  border-radius: 3px;
  font-weight: 500;
  margin-bottom: 8px;
  border: 1px solid currentColor;
}

.entity-name {
  font-family: var(--main-font);
  font-weight: 500;
  font-size: 1.6rem;
  color: var(--text-heading);
  cursor: pointer;
  padding: 4px 12px;
  border-radius: 6px;
  transition: background-color 0.2s, transform 0.2s;
  display: inline-block;
  max-width: 100%;
}

.entity-name:active {
  background-color: var(--highlight-bg-color);
  transform: scale(0.97);
}

/* Underline link effect */
.entity-name::after {
  content: "";
  display: block;
  width: 30%;
  height: 1.5px;
  background-color: var(--brand-color);
  margin: 2px auto 0 auto;
  opacity: 0.25;
  transition: width 0.2s;
}

/* ==========================================================================
   Fixed Central Divider Overlay (The Relationship HUD Line)
   ========================================================================== */
#central-divider-overlay {
  position: absolute;
  top: calc(var(--header-height) + (100vh - var(--header-height)) / 2);
  top: calc(var(--header-height) + (100dvh - var(--header-height)) / 2);
  left: 0;
  width: 100%;
  height: 0;
  z-index: 100;
  pointer-events: none; /* Let scrolls go through the line */
}

/* Interactive relationship trigger button */
#divider-trigger-btn {
  position: absolute;
  top: 0;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--card-bg);
  border: 1.5px solid var(--brand-color);
  color: var(--brand-color);
  font-family: var(--main-font);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 3px 14px;
  border-radius: 20px;
  cursor: pointer;
  pointer-events: auto; /* Enable clicking */
  box-shadow: 0 2px 8px rgba(27, 54, 93, 0.08);
  display: flex;
  align-items: center;
  gap: 4px;
  transition: opacity 0.25s ease, transform 0.25s ease, background 0.2s, color 0.2s, box-shadow 0.2s;
}

#divider-trigger-btn.is-scrolling {
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.8);
  pointer-events: none;
}

#divider-trigger-btn:active {
  background: var(--brand-color);
  color: var(--card-bg);
  box-shadow: 0 1px 4px rgba(27, 54, 93, 0.15);
}

/* Small visual link indicator */
.divider-btn-icon::after {
  content: " ⇄";
  font-size: 0.72rem;
  vertical-align: middle;
}

/* ==========================================================================
   Relationship Popup Card (Centered HUD Popup)
   ========================================================================== */
#relation-detail-popup {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0.95);
  width: 88vw;
  max-width: 400px;
  background: var(--card-bg);
  border: 1.5px solid var(--brand-color);
  border-radius: 8px;
  padding: 24px;
  box-shadow: 0 8px 32px rgba(27, 54, 93, 0.15);
  z-index: 200;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

#relation-detail-popup.active {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
  pointer-events: auto;
}

.popup-relation-type {
  font-family: var(--main-font);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-type-event);
  text-align: center;
  border-bottom: 1px dashed rgba(27, 54, 93, 0.1);
  padding-bottom: 8px;
  margin-bottom: 12px;
}

.popup-relation-desc {
  font-family: var(--main-font);
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-main);
  margin-bottom: 18px;
  text-align: justify;
}

.popup-close-btn {
  background: transparent;
  border: 1.2px solid var(--brand-color);
  color: var(--brand-color);
  padding: 4px 16px;
  border-radius: 4px;
  font-family: var(--main-font);
  font-size: 0.75rem;
  font-weight: 500;
  cursor: pointer;
  display: block;
  margin: 0 auto;
  transition: all 0.2s;
}

.popup-close-btn:active {
  background: var(--brand-color);
  color: var(--card-bg);
}

/* ==========================================================================
   Roaming Branch Selector (Paging Pager in Bottom Card)
   ========================================================================== */
.roam-navigator {
  display: none; /* Hidden by default */
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-top: 10px;
  width: 100%;
}

/* Display only on bottom active card */
.relation-card.is-bottom .roam-navigator {
  display: flex;
}

.roam-arrow-btn {
  background: var(--highlight-bg-color);
  border: 0.5px solid rgba(27, 54, 93, 0.15);
  color: var(--brand-color);
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  cursor: pointer;
  font-weight: bold;
  transition: all 0.2s;
}

.roam-arrow-btn:active {
  background-color: var(--card-bg);
}

.roam-arrow-btn.disabled {
  opacity: 0.25;
  pointer-events: none;
}

.roam-path-indicator {
  font-size: 0.72rem;
  color: var(--text-main);
  letter-spacing: 0.5px;
}

/* ==========================================================================
   Scroll Indicator
   ========================================================================== */
.scroll-indicator {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  opacity: 0.7;
  pointer-events: none;
  z-index: 4;
  transition: opacity 0.3s;
}

.scroll-indicator.fade-out {
  opacity: 0;
}

.indicator-text {
  font-size: 0.68rem;
  color: var(--text-main);
  letter-spacing: 0.5px;
}

.indicator-arrow {
  width: 5px;
  height: 5px;
  border-right: 1.2px solid var(--text-main);
  border-bottom: 1.2px solid var(--text-main);
  transform: rotate(45deg);
  animation: arrowBounce 1.5s infinite;
}

@keyframes arrowBounce {
  0%, 100% { transform: translateY(0) rotate(45deg); }
  50% { transform: translateY(3px) rotate(45deg); }
}

/* ==========================================================================
   Bottom Sheet (Entity Detail Panel)
   ========================================================================== */
.drawer-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(20, 20, 19, 0.4); /* Translucent dark charcoal */
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  z-index: 1000;
}

.drawer-overlay.active {
  opacity: 1;
  visibility: visible;
}

.bottom-sheet {
  position: fixed;
  bottom: 0;
  left: 0;
  width: 100vw;
  max-height: 80vh;
  background: var(--card-bg);
  border-top: 1.5px solid var(--brand-color);
  border-top-left-radius: 12px;
  border-top-right-radius: 12px;
  z-index: 1001;
  transform: translateY(100%);
  visibility: hidden;
  transition: transform 0.3s cubic-bezier(0.25, 1, 0.5, 1), visibility 0.3s;
  display: flex;
  flex-direction: column;
  box-shadow: 0 -8px 24px rgba(27, 54, 93, 0.1);
  padding-bottom: var(--safe-area-bottom);
}

.bottom-sheet.active {
  transform: translateY(0);
  visibility: visible;
}

.sheet-drag-handle {
  width: 36px;
  height: 3px;
  background: var(--brand-color);
  opacity: 0.15;
  border-radius: 2px;
  margin: 10px auto 4px auto;
}

.sheet-close-btn {
  position: absolute;
  top: 10px;
  right: 14px;
  background: var(--highlight-bg-color);
  border: none;
  color: var(--brand-color);
  font-size: 1.3rem;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.sheet-close-btn:active {
  background-color: var(--card-bg);
}

.sheet-content {
  flex: 1;
  overflow-y: auto;
  padding: 10px 20px 20px 20px;
}

.entity-detail-header {
  margin-bottom: 16px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 4px;
}

.entity-badge {
  font-size: 0.68rem;
  padding: 1px 5px;
  border-radius: 2px;
  font-weight: 500;
  border: 1px solid;
}

.entity-detail-title {
  font-family: var(--main-font);
  font-weight: 500;
  font-size: 1.4rem;
  color: var(--brand-color);
}

.entity-detail-body h3 {
  font-family: var(--main-font);
  font-size: 0.8rem;
  color: var(--brand-color);
  margin-bottom: 8px;
  border-left: 2px solid var(--brand-color);
  padding-left: 8px;
}

.entity-description-section {
  margin-bottom: 20px;
}

.desc-item {
  margin-bottom: 10px;
  padding-bottom: 10px;
  border-bottom: 1px dashed rgba(27, 54, 93, 0.06);
}

.desc-item:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.desc-chap-title {
  font-size: 0.72rem;
  font-weight: bold;
  color: var(--brand-color);
  opacity: 0.8;
  margin-bottom: 3px;
}

.desc-text {
  font-size: 0.82rem;
  color: var(--text-main);
  line-height: 1.55;
}

.entity-connections-section {
  margin-top: 16px;
}

.connections-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.conn-chip {
  background: var(--card-bg);
  border: 0.5px solid var(--border-color);
  color: var(--text-main);
  padding: 5px 10px;
  border-radius: 4px;
  font-size: 0.78rem;
  font-family: var(--main-font);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: all 0.2s;
}

.conn-chip:active {
  border-color: var(--brand-color);
  background-color: var(--highlight-bg-color);
  color: var(--brand-color);
}

.conn-type {
  font-size: 0.62rem;
  color: var(--color-type-event);
  background: var(--highlight-bg-color);
  padding: 0px 3px;
  border-radius: 2px;
}

/* ==========================================================================
   Right Drawer (Index List Drawer)
   ========================================================================== */
.right-drawer {
  position: fixed;
  top: 0;
  right: 0;
  width: 85vw;
  max-width: 340px;
  height: 100vh;
  background: var(--card-bg);
  border-left: 1.5px solid var(--brand-color);
  z-index: 1002;
  transform: translateX(100%);
  visibility: hidden;
  transition: transform 0.3s cubic-bezier(0.25, 1, 0.5, 1), visibility 0.3s;
  display: flex;
  flex-direction: column;
  box-shadow: -8px 0 24px rgba(27, 54, 93, 0.1);
}

.right-drawer.active {
  transform: translateX(0);
  visibility: visible;
}


.drawer-header {
  height: var(--header-height);
  padding: 0 16px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-color);
}

.drawer-header h2 {
  font-family: var(--main-font);
  font-size: 1.05rem;
  color: var(--brand-color);
  font-weight: 500;
}

.drawer-close-btn {
  background: transparent;
  border: none;
  color: var(--brand-color);
  font-size: 1.6rem;
  cursor: pointer;
}

.search-box-wrapper {
  padding: 10px 16px;
  position: relative;
  border-bottom: 1px solid var(--border-color);
}

#search-input {
  width: 100%;
  background: var(--bg-page);
  border: 1px solid var(--border-color);
  border-radius: 4px;
  padding: 6px 12px 6px 30px;
  color: var(--text-main);
  font-size: 0.8rem;
  outline: none;
  font-family: var(--main-font);
  transition: border-color 0.2s;
}

#search-input:focus {
  border-color: var(--brand-color);
}

.search-icon {
  position: absolute;
  left: 24px;
  top: 52%;
  transform: translateY(-50%);
  color: var(--brand-color);
  opacity: 0.5;
  pointer-events: none;
}

.category-filters {
  padding: 6px 16px;
  display: flex;
  gap: 5px;
  overflow-x: auto;
  white-space: nowrap;
  border-bottom: 1px solid var(--border-color);
}

.filter-chip {
  background: var(--bg-page);
  border: 0.5px solid var(--border-color);
  color: var(--text-main);
  padding: 3px 8px;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 500;
  font-family: var(--main-font);
  cursor: pointer;
}

.filter-chip.active {
  background: var(--brand-color);
  border-color: var(--brand-color);
  color: var(--card-bg);
  font-weight: 500;
}

.drawer-scroll-content {
  flex: 1;
  overflow-y: auto;
}

.entity-index-list {
  list-style: none;
}

.index-item {
  padding: 10px 16px;
  border-bottom: 1px solid rgba(27, 54, 93, 0.04);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transition: background 0.2s;
}

.index-item:active {
  background-color: var(--highlight-bg-color);
}

.index-item-name {
  font-weight: 500;
  font-size: 0.88rem;
  color: var(--text-heading);
}

.index-item-type {
  font-size: 0.62rem;
  padding: 1px 4px;
  border-radius: 2px;
  opacity: 0.9;
  border: 0.5px solid;
}

/* ==========================================================================
   Welcome / Tutorial Overlay
   ========================================================================== */
.welcome-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: var(--bg-page);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  transition: opacity 0.3s ease, visibility 0.3s ease;
}

.welcome-overlay.hidden {
  opacity: 0;
  visibility: hidden;
}

.welcome-card {
  width: 100%;
  max-width: 380px;
  background: var(--card-bg);
  border: 1.5px solid var(--brand-color);
  border-radius: 8px;
  padding: 28px 20px;
  text-align: center;
  box-shadow: 0 8px 28px rgba(27, 54, 93, 0.08);
}

.welcome-title {
  font-family: var(--main-font);
  font-weight: 700;
  font-size: 1.7rem;
  color: var(--brand-color);
  margin-bottom: 4px;
}

.welcome-subtitle {
  font-size: 0.72rem;
  color: var(--text-main);
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 20px;
  opacity: 0.8;
}

.welcome-guide {
  display: flex;
  flex-direction: column;
  gap: 12px;
  text-align: left;
  margin-bottom: 24px;
}

.guide-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
}

.guide-icon {
  font-size: 1rem;
  margin-top: 1px;
}

.guide-text {
  font-size: 0.78rem;
  color: var(--text-main);
  line-height: 1.5;
}

.guide-text strong {
  color: var(--brand-color);
}

.welcome-btn {
  background: var(--brand-color);
  color: var(--card-bg);
  border: none;
  font-family: var(--main-font);
  font-weight: 500;
  font-size: 0.9rem;
  padding: 8px 28px;
  border-radius: 4px;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(27, 54, 93, 0.15);
  transition: all 0.2s;
}

.welcome-btn:active {
  transform: translateY(1px);
  box-shadow: 0 2px 6px rgba(27, 54, 93, 0.15);
}

/* ==========================================================================
   Sophisticated Category colors for Scholarly Light Theme
   ========================================================================== */
.type-person { color: var(--color-type-person); }
.type-group { color: var(--color-type-group); }
.type-location { color: var(--color-type-location); }
.type-system { color: var(--color-type-system); }
.type-event { color: var(--color-type-event); }

/* Color overrides for backgrounds & borders */
.bg-type-person {
  border-color: rgba(160, 106, 59, 0.3);
  background-color: rgba(160, 106, 59, 0.05);
}
.bg-type-group {
  border-color: rgba(27, 54, 93, 0.3);
  background-color: rgba(27, 54, 93, 0.05);
}
.bg-type-location {
  border-color: rgba(58, 99, 81, 0.3);
  background-color: rgba(58, 99, 81, 0.05);
}
.bg-type-system {
  border-color: rgba(109, 76, 65, 0.3);
  background-color: rgba(109, 76, 65, 0.05);
}
.bg-type-event {
  border-color: rgba(181, 51, 51, 0.3);
  background-color: rgba(181, 51, 51, 0.05);
}