:root {
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --bg-color: #f3f4f6;
  --sidebar-bg: #ffffff;
  --chat-bg: #f3f4f6;
  --card-bg: #ffffff;
  --text-main: #1f2937;
  --text-sub: #6b7280;
  --border-color: #e5e7eb;
  --bubble-left: #ffffff;
  --bubble-center: #e0f2fe;
  --bubble-right: #dbeafe;
  --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #111827;
    --sidebar-bg: #1f2937;
    --chat-bg: #111827;
    --card-bg: #374151;
    --text-main: #f9fafb;
    --text-sub: #9ca3af;
    --border-color: #374151;
    --bubble-left: #374151;
    --bubble-center: #1e3a8a;
    --bubble-right: #1e40af;
  }
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  height: 100vh;
  overflow: hidden;
}

/* Layout */
.app-layout {
  display: flex;
  height: 100vh;
}

/* Sidebar */
.sidebar {
  width: 300px;
  background-color: var(--sidebar-bg);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
}

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

.book-list {
  flex: 1;
  overflow-y: auto;
  padding: 0.5rem;
}

.book-item {
  padding: 0.75rem;
  border-radius: 0.5rem;
  cursor: pointer;
  margin-bottom: 0.25rem;
}

.book-item:hover {
  background-color: var(--bg-color);
}

.book-item.active {
  background-color: var(--primary-color);
  color: white;
}

.book-item.active .book-author {
  color: #e5e7eb;
}

.book-title {
  font-weight: bold;
  margin-bottom: 0.25rem;
}

.book-author {
  font-size: 0.875rem;
  color: var(--text-sub);
}

.sidebar-footer {
  padding: 1rem;
  border-top: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.user-email {
  font-size: 0.875rem;
  color: var(--text-main);
  font-weight: 500;
  overflow: hidden;
  text-overflow: ellipsis;
}

.logout-btn {
  background: none;
  border: 1px solid var(--border-color);
  padding: 0.5rem;
  border-radius: 0.25rem;
  cursor: pointer;
  color: var(--text-sub);
  font-size: 0.875rem;
  transition: all 0.2s;
}

.logout-btn:hover {
  background-color: #fee2e2;
  color: #ef4444;
  border-color: #fecaca;
}

@media (prefers-color-scheme: dark) {
  .logout-btn:hover {
    background-color: #7f1d1d;
    color: #fca5a5;
    border-color: #991b1b;
  }
}

/* Chat Area */
.chat-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  background-color: var(--chat-bg);
  position: relative;
}

.chat-header {
  padding: 1rem;
  background-color: var(--sidebar-bg);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.timeline {
  flex: 1;
  overflow-y: auto;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Chat Bubbles */
.message-row {
  display: flex;
  width: 100%;
}

.message-row.left {
  justify-content: flex-start;
}

.message-row.center {
  justify-content: center;
}

.message-row.right {
  justify-content: flex-end;
}

.bubble {
  max-width: 70%;
  padding: 0.75rem 1rem;
  border-radius: 1rem;
  box-shadow: var(--shadow);
  position: relative;
}

.message-row.left .bubble {
  background-color: var(--bubble-left);
  border-bottom-left-radius: 0.25rem;
}

.message-row.center .bubble {
  background-color: var(--bubble-center);
  border-radius: 0.5rem;
  text-align: center;
  width: 80%;
  max-width: 600px;
}

.message-row.right .bubble {
  background-color: var(--bubble-right);
  color: white;
  border-bottom-right-radius: 0.25rem;
}

.meta {
  font-size: 0.75rem;
  color: var(--text-sub);
  margin-top: 0.25rem;
  text-align: right;
}

.message-row.center .meta {
  text-align: center;
}

.actions {
  display: inline-flex;
  gap: 0.5rem;
  margin-left: 0.5rem;
  opacity: 0;
  transition: opacity 0.2s;
}

.bubble:hover .actions {
  opacity: 1;
}

.action-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-size: 0.9rem;
  color: var(--text-sub);
  padding: 0;
}

.action-btn:hover {
  color: var(--primary-color);
}

.edit-textarea {
  width: 100%;
  min-height: 60px;
  padding: 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: 0.25rem;
  background-color: var(--bg-color);
  color: var(--text-main);
  margin-bottom: 0.5rem;
  resize: vertical;
}

.edit-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
}

.save-btn,
.cancel-btn {
  padding: 0.25rem 0.75rem;
  border-radius: 0.25rem;
  font-size: 0.875rem;
  cursor: pointer;
}

.save-btn {
  background-color: var(--primary-color);
  color: white;
  border: none;
}

.cancel-btn {
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-main);
}

/* Input Area */
.input-area {
  padding: 1rem;
  background-color: var(--sidebar-bg);
  border-top: 1px solid var(--border-color);
}

.input-container {
  display: flex;
  gap: 0.5rem;
  align-items: flex-end;
  max-width: 800px;
  margin: 0 auto;
}

textarea {
  flex: 1;
  min-height: 44px;
  max-height: 40vh;
  padding: 0.75rem;
  border-radius: 1.5rem;
  border: 1px solid var(--border-color);
  resize: none;
  background-color: var(--bg-color);
  color: var(--text-main);
}

.send-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
}

.icon-btn {
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: var(--primary-color);
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .app-layout {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    height: auto;
    max-height: 30vh;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
  }

  .sidebar.collapsed .book-list {
    display: none;
  }

  /* Add toggle logic later if needed */
}

/* Modal */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  z-index: 200;
  align-items: center;
  justify-content: center;
}

.modal.active {
  display: flex;
}

.modal-content {
  background-color: var(--sidebar-bg);
  padding: 1.5rem;
  border-radius: 0.75rem;
  width: 90%;
  max-width: 400px;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.close-btn {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
}

input {
  width: 100%;
  padding: 0.5rem;
  margin-bottom: 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: 0.25rem;
  background-color: var(--bg-color);
  color: var(--text-main);
}