/* ========================================
   CSS Variables & Theme
   ======================================== */
:root {
  --color-primary: #1a365d;
  --color-primary-light: #2c5282;
  --color-primary-dark: #0f2440;
  --color-accent: #2b6cb0;
  --color-accent-light: #ebf4ff;

  --color-bg: #f7f8fa;
  --color-bg-card: #ffffff;
  --color-bg-sidebar: #ffffff;
  --color-bg-topbar: #ffffff;
  --color-bg-hover: #f0f4f8;
  --color-bg-active: #e8f0fe;

  --color-text: #1a202c;
  --color-text-secondary: #4a5568;
  --color-text-muted: #718096;
  --color-text-inverse: #ffffff;

  --color-border: #e2e8f0;
  --color-border-light: #edf2f7;

  --color-success: #38a169;
  --color-warning: #d69e2e;
  --color-danger: #e53e3e;
  --color-info: #3182ce;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);

  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-2xl: 48px;

  --font-sans: -apple-system, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;

  --topbar-height: 56px;
  --footer-height: 40px;
  --nav-width: 220px;

  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

[data-theme="dark"] {
  --color-bg: #1a202c;
  --color-bg-card: #2d3748;
  --color-bg-sidebar: #1e2a3a;
  --color-bg-topbar: #1a202c;
  --color-bg-hover: #374151;
  --color-bg-active: #2c5282;

  --color-text: #e2e8f0;
  --color-text-secondary: #a0aec0;
  --color-text-muted: #718096;

  --color-border: #4a5568;
  --color-border-light: #374151;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-light);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: var(--color-text);
}

input {
  font-family: inherit;
  border: none;
  outline: none;
  background: none;
  color: var(--color-text);
}

kbd {
  display: inline-block;
  padding: 2px 6px;
  font-size: 12px;
  font-family: var(--font-mono);
  background: var(--color-bg-hover);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  color: var(--color-text-muted);
}

/* ========================================
   Topbar (simplified)
   ======================================== */
.topbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--topbar-height);
  background: var(--color-bg-topbar);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 var(--spacing-lg);
  z-index: 100;
  box-shadow: var(--shadow-sm);
}

.topbar__left {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  flex-shrink: 0;
}

.topbar__menu-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.topbar__menu-btn:hover {
  background: var(--color-bg-hover);
  color: var(--color-text);
}

.topbar__logo {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  background: var(--color-primary);
  color: var(--color-text-inverse);
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 16px;
}

.topbar__title {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
}

.topbar__right {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  flex-shrink: 0;
  margin-left: auto;
}

.topbar__search-btn,
.topbar__theme-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
}

.topbar__search-btn:hover,
.topbar__theme-btn:hover {
  background: var(--color-bg-hover);
  color: var(--color-text);
}

/* ========================================
   Layout: sidebar-nav + content-area
   ======================================== */
.layout {
  display: flex;
  flex: 1;
  margin-top: var(--topbar-height);
  min-height: calc(100vh - var(--topbar-height) - var(--footer-height));
}

/* ========================================
   Sidebar Navigation
   ======================================== */
.sidebar-nav {
  width: var(--nav-width);
  background: var(--color-bg-sidebar);
  border-right: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  position: fixed;
  top: var(--topbar-height);
  bottom: var(--footer-height);
  left: 0;
  z-index: 50;
  overflow: hidden;
  transition: transform var(--transition-normal);
}

.sidebar-nav__header {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md);
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}

.sidebar-nav__brand {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
}

.sidebar-nav__modules {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-sm) 0;
}

.sidebar-nav__item {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  color: var(--color-text-secondary);
  transition: all var(--transition-fast);
  text-decoration: none;
  border-left: 3px solid transparent;
}

.sidebar-nav__item:hover {
  background: var(--color-bg-hover);
  color: var(--color-text);
}

.sidebar-nav__item--active {
  background: var(--color-bg-active);
  color: var(--color-accent);
  border-left-color: var(--color-accent);
}

.sidebar-nav__item--active .sidebar-nav__item-title {
  font-weight: 600;
}

.sidebar-nav__item-icon {
  font-size: 18px;
  flex-shrink: 0;
  line-height: 1.4;
}

.sidebar-nav__item-text {
  min-width: 0;
}

.sidebar-nav__item-title {
  font-size: 13px;
  font-weight: 500;
  line-height: 1.3;
}

.sidebar-nav__item-desc {
  font-size: 11px;
  color: var(--color-text-muted);
  line-height: 1.4;
  margin-top: 2px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.sidebar-nav__footer {
  flex-shrink: 0;
  border-top: 1px solid var(--color-border);
  padding: var(--spacing-sm);
}

.sidebar-nav__stats {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.stat-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--color-bg);
  border-radius: var(--radius-sm);
  font-size: 12px;
}

.stat-item__label {
  color: var(--color-text-secondary);
  flex: 1;
}

.stat-item__value {
  font-weight: 600;
  color: var(--color-text);
}

.stat-item__rank {
  font-size: 10px;
  color: var(--color-success);
  background: #f0fff4;
  padding: 1px 5px;
  border-radius: 10px;
  font-weight: 500;
}

[data-theme="dark"] .stat-item__rank {
  background: #22543d;
}

.sidebar-nav__backdrop {
  display: none;
  position: fixed;
  inset: 0;
  top: var(--topbar-height);
  z-index: 40;
  background: rgba(0, 0, 0, 0.4);
}

/* ========================================
   Content Area
   ======================================== */
.content-area {
  flex: 1;
  margin-left: var(--nav-width);
  min-width: 0;
  display: flex;
  flex-direction: column;
}

.content-area__body {
  flex: 1;
  padding: var(--spacing-lg);
  overflow-y: auto;
}

/* ========================================
   Module View
   ======================================== */
.module-view__header {
  margin-bottom: var(--spacing-md);
}

.module-view__content {
  min-height: 200px;
}

/* ========================================
   AI Panel (collapsible)
   ======================================== */
.ai-panel {
  margin-top: var(--spacing-xl);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-bg-card);
}

.ai-panel__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--color-bg);
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast);
}

.ai-panel__header:hover {
  background: var(--color-bg-hover);
}

.ai-panel__title {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
}

.ai-panel__chevron {
  color: var(--color-text-muted);
  transition: transform var(--transition-normal);
}

.ai-panel--collapsed .ai-panel__chevron {
  transform: rotate(-90deg);
}

.ai-panel__body {
  transition: max-height var(--transition-normal), opacity var(--transition-normal);
  max-height: 350px;
  opacity: 1;
  overflow: hidden;
}

.ai-panel--collapsed .ai-panel__body {
  max-height: 0;
  opacity: 0;
}

.ai-panel--collapsed .ai-panel__body .ai-chat {
  height: 0;
  border: none;
}

/* ========================================
   Results Panel (collapsible)
   ======================================== */
.results-panel {
  margin-top: var(--spacing-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-bg-card);
}

.results-panel__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-sm) var(--spacing-md);
  background: var(--color-bg);
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast);
}

.results-panel__header:hover {
  background: var(--color-bg-hover);
}

.results-panel__title {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-secondary);
}

.results-panel__chevron {
  color: var(--color-text-muted);
  transition: transform var(--transition-normal);
}

.results-panel--collapsed .results-panel__chevron {
  transform: rotate(-90deg);
}

.results-panel__body {
  transition: max-height var(--transition-normal), opacity var(--transition-normal);
  max-height: 500px;
  opacity: 1;
  overflow: hidden;
}

.results-panel--collapsed .results-panel__body {
  max-height: 0;
  opacity: 0;
}

.results-list {
  padding: var(--spacing-md);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.result-card {
  padding: var(--spacing-sm) var(--spacing-md);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.result-card:hover {
  border-color: var(--color-accent);
  background: var(--color-accent-light);
}

.result-card__title {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
}

.result-card__summary {
  font-size: 12px;
  color: var(--color-text-secondary);
  margin-top: var(--spacing-xs);
  line-height: 1.5;
}

.result-card__date {
  font-size: 11px;
  color: var(--color-text-muted);
  margin-top: var(--spacing-xs);
}

/* ========================================
   Footer
   ======================================== */
.footer {
  height: var(--footer-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--spacing-lg);
  font-size: 12px;
  color: var(--color-text-muted);
  border-top: 1px solid var(--color-border);
}

/* ========================================
   Responsive
   ======================================== */
@media (max-width: 900px) {
  .topbar__menu-btn {
    display: flex;
  }

  .sidebar-nav {
    transform: translateX(-100%);
  }

  .sidebar-nav--open {
    transform: translateX(0);
  }

  .sidebar-nav__backdrop--visible {
    display: block;
  }

  .content-area {
    margin-left: 0;
  }
}

@media (max-width: 600px) {
  .content-area__body {
    padding: var(--spacing-md);
  }
}