:root {
  --primary: #7B1FA2;
  --primary-dark: #4A148C;
  --primary-light: #CE93D8;
  --primary-surface: #F3E5F5;
  --on-primary: #FFFFFF;
  --surface: #FFFFFF;
  --surface-variant: #F5F5F5;
  --background: #FAFAFA;
  --on-surface: #212121;
  --on-surface-medium: #616161;
  --on-surface-dim: #9E9E9E;
  --outline: #E0E0E0;
  --outline-variant: #EEEEEE;
  --elevation-1: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.08);
  --elevation-2: 0 3px 6px rgba(0,0,0,0.15), 0 2px 4px rgba(0,0,0,0.10);
  --elevation-3: 0 10px 20px rgba(0,0,0,0.15), 0 3px 6px rgba(0,0,0,0.10);
  --radius: 12px;
  --radius-sm: 8px;
  --radius-xs: 4px;
  --transition: 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --primary: #CE93D8;
  --primary-dark: #E1BEE7;
  --primary-light: #7B1FA2;
  --primary-surface: #1E1A2E;
  --surface: #1E1E2E;
  --surface-variant: #2A2A3C;
  --background: #12121A;
  --on-surface: #E0E0E0;
  --on-surface-medium: #A0A0B0;
  --on-surface-dim: #6E6E80;
  --outline: #3A3A4C;
  --outline-variant: #2A2A3C;
  --elevation-1: 0 1px 3px rgba(0,0,0,0.4), 0 1px 2px rgba(0,0,0,0.3);
  --elevation-2: 0 3px 6px rgba(0,0,0,0.5), 0 2px 4px rgba(0,0,0,0.4);
  --elevation-3: 0 10px 20px rgba(0,0,0,0.5), 0 3px 6px rgba(0,0,0,0.4);
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--background);
  color: var(--on-surface);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background var(--transition), color var(--transition);
}

/* ── App Bar ────────────────────────────── */
.app-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  height: 64px;
  background: linear-gradient(135deg, var(--primary-dark), var(--primary));
  color: #FFFFFF;
  box-shadow: var(--elevation-2);
  position: sticky;
  top: 0;
  z-index: 100;
  gap: 16px;
  flex-shrink: 0;
}

.app-bar-left {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.logo-icon {
  font-size: 1.6rem;
  line-height: 1;
}

.app-title {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 0.5px;
}

.app-subtitle {
  font-size: 0.8rem;
  opacity: 0.8;
  font-weight: 400;
  padding-left: 2px;
  margin-inline-start: 2px;
  border-inline-start: 1px solid rgba(255,255,255,0.3);
  padding-inline-start: 10px;
}

.app-bar-right {
  display: flex;
  align-items: center;
  gap: 12px;
}

.search-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.search-icon {
  position: absolute;
  inset-inline-start: 12px;
  width: 18px;
  height: 18px;
  color: rgba(255,255,255,0.7);
  pointer-events: none;
}

.search-input {
  width: 220px;
  height: 40px;
  padding: 0 16px 0 40px;
  border: none;
  border-radius: 20px;
  background: rgba(255,255,255,0.15);
  color: #FFFFFF;
  font-size: 0.9rem;
  outline: none;
  transition: background var(--transition), width var(--transition);
}

.search-input::placeholder {
  color: rgba(255,255,255,0.5);
}

.search-input:focus {
  background: rgba(255,255,255,0.25);
  width: 260px;
}

.icon-btn {
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 50%;
  background: rgba(255,255,255,0.15);
  color: #FFFFFF;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--transition);
  flex-shrink: 0;
}

.icon-btn:hover {
  background: rgba(255,255,255,0.3);
}

.icon-btn svg {
  width: 20px;
  height: 20px;
}

[data-theme="light"] .icon-moon { display: block; }
[data-theme="light"] .icon-sun  { display: none; }
[data-theme="dark"]  .icon-moon { display: none; }
[data-theme="dark"]  .icon-sun  { display: block; }

/* ── Language Tabs ──────────────────────── */
.lang-tabs-wrapper {
  background: var(--surface);
  border-bottom: 1px solid var(--outline);
  box-shadow: var(--elevation-1);
  position: sticky;
  top: 64px;
  z-index: 99;
  overflow-x: auto;
  flex-shrink: 0;
}

.lang-tabs {
  display: flex;
  gap: 0;
  padding: 0 16px;
  max-width: 1200px;
  margin: 0 auto;
  min-width: max-content;
}

.lang-tab {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 12px 20px 10px;
  border: none;
  background: transparent;
  color: var(--on-surface-medium);
  cursor: pointer;
  font-family: inherit;
  font-size: 0.85rem;
  position: relative;
  transition: color var(--transition), background var(--transition);
  white-space: nowrap;
  border-bottom: 3px solid transparent;
}

.lang-tab:hover {
  color: var(--primary);
  background: var(--primary-surface);
}

.lang-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

.lang-tab.hidden {
  display: none;
}

.tab-code {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.5px;
  opacity: 0.7;
}

.tab-name {
  font-size: 0.9rem;
}

/* ── Viewer ─────────────────────────────── */
.viewer-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 24px 16px;
}

.viewer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.current-lang-label {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--on-surface);
}

.badge {
  background: var(--primary-surface);
  color: var(--primary-dark);
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 600;
}

.pdf-viewer {
  flex: 1;
  display: flex;
}

.pdf-embed {
  width: 100%;
  flex: 1;
  min-height: 500px;
  border: none;
}

.pdf-error {
  display: none;
  flex: 1;
  min-height: 200px;
  align-items: center;
  justify-content: center;
}

.error-content {
  text-align: center;
  color: var(--on-surface-medium);
  padding: 32px;
}

.error-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 12px;
  opacity: 0.5;
}

/* ── Action Bar ─────────────────────────── */
.action-bar {
  display: flex;
  gap: 12px;
  margin-top: 20px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  text-decoration: none;
  transition: background var(--transition), box-shadow var(--transition), transform var(--transition);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--primary);
  color: #FFFFFF;
  box-shadow: var(--elevation-1);
}

.btn-primary:hover {
  background: var(--primary-dark);
  box-shadow: var(--elevation-2);
}

.btn-secondary {
  background: var(--surface-variant);
  color: var(--on-surface);
  border: 1px solid var(--outline);
}

.btn-secondary:hover {
  background: var(--outline-variant);
}

.btn-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

/* ── Toast ──────────────────────────────── */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--on-surface);
  color: var(--surface);
  padding: 10px 24px;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: 500;
  opacity: 0;
  transition: transform 300ms ease, opacity 300ms ease;
  z-index: 200;
  pointer-events: none;
  box-shadow: var(--elevation-3);
}

.toast.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

/* ── Footer ─────────────────────────────── */
.app-footer {
  text-align: center;
  padding: 16px;
  font-size: 0.8rem;
  color: var(--on-surface-dim);
  border-top: 1px solid var(--outline-variant);
  background: var(--surface);
  flex-shrink: 0;
}

/* ── Responsive ─────────────────────────── */
@media (max-width: 768px) {
  .app-bar {
    padding: 0 12px;
    height: 56px;
  }

  .app-subtitle {
    display: none;
  }

  .app-title {
    font-size: 1.1rem;
  }

  .search-input {
    width: 140px;
  }

  .search-input:focus {
    width: 180px;
  }

  .lang-tabs {
    padding: 0 8px;
  }

  .lang-tab {
    padding: 10px 14px 8px;
  }

  .tab-name {
    font-size: 0.8rem;
  }

  .viewer-container {
    padding: 16px 8px;
  }

  .btn {
    padding: 10px 18px;
    font-size: 0.85rem;
  }

  .current-lang-label {
    font-size: 1rem;
  }
}

@media (max-width: 480px) {
  .app-bar-right {
    gap: 6px;
  }

  .search-input {
    width: 110px;
    font-size: 0.8rem;
    padding: 0 8px 0 32px;
    height: 36px;
  }

  .search-icon {
    inset-inline-start: 8px;
    width: 16px;
    height: 16px;
  }

  .icon-btn {
    width: 36px;
    height: 36px;
  }

  .lang-tab {
    padding: 8px 10px 6px;
  }

  .tab-name {
    font-size: 0.75rem;
  }

  .action-bar {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }
}

/* ── Scrollbar styling ──────────────────── */
.lang-tabs-wrapper::-webkit-scrollbar {
  height: 4px;
}

.lang-tabs-wrapper::-webkit-scrollbar-track {
  background: transparent;
}

.lang-tabs-wrapper::-webkit-scrollbar-thumb {
  background: var(--outline);
  border-radius: 2px;
}