:root {
  --bg-primary: #212121;
  --bg-secondary: #171717;
  --bg-tertiary: #2f2f2f;
  --bg-hover: #383838;
  --bg-active: #404040;
  --text-primary: #ececec;
  --text-secondary: #b4b4b4;
  --text-muted: #8e8e8e;
  --border-color: #383838;
  --accent-color: #10a37f;
  --accent-hover: #0d8c6d;
  --user-bubble: #2f2f2f;
  --ai-bubble: transparent;
  --shadow-sm: 0 1px 2px 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);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --sidebar-width: 260px;
  --top-bar-height: 52px;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow: hidden;
  height: 100vh;
}

.app-container {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  transition: transform var(--transition-normal);
  z-index: 100;
}

.sidebar-header {
  padding: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.new-chat-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 16px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.new-chat-btn:hover {
  background: var(--bg-hover);
}

.sidebar-toggle {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

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

.sidebar-search {
  margin: 0 12px 12px;
  position: relative;
}

.sidebar-search svg {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

.sidebar-search input {
  width: 100%;
  padding: 10px 12px 10px 36px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
  transition: all var(--transition-fast);
}

.sidebar-search input::placeholder {
  color: var(--text-muted);
}

.sidebar-search input:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 2px rgba(16, 163, 127, 0.2);
}

.conversations-list {
  flex: 1;
  overflow-y: auto;
  padding: 0 8px;
}

.conversation-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  margin-bottom: 2px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

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

.conversation-item.active {
  background: var(--bg-active);
}

.conversation-item .conv-icon {
  color: var(--text-muted);
  flex-shrink: 0;
}

.conversation-item .conv-title {
  flex: 1;
  font-size: 14px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--text-primary);
}

.conversation-item .conv-actions {
  display: none;
  gap: 4px;
}

.conversation-item:hover .conv-actions {
  display: flex;
}

.conv-action-btn {
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.conv-action-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

.sidebar-footer {
  padding: 12px;
  border-top: 1px solid var(--border-color);
}

.user-profile {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.user-profile:hover {
  background: var(--bg-hover);
}

.user-avatar {
  width: 32px;
  height: 32px;
  background: var(--accent-color);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 14px;
  color: white;
}

.user-info {
  flex: 1;
}

.user-name {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}

.user-plan {
  font-size: 12px;
  color: var(--text-muted);
}

/* Main Content */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  position: relative;
}

.top-bar {
  height: var(--top-bar-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-primary);
  z-index: 10;
}

.mobile-menu-btn {
  display: none;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
}

.model-selector {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.model-selector:hover {
  background: var(--bg-hover);
}

.model-name {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
}

.top-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

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

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

/* Chat Area */
.chat-area {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  scroll-behavior: smooth;
}

/* Welcome Screen */
.welcome-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
  padding: 40px 20px;
}

.welcome-logo {
  margin-bottom: 24px;
  color: var(--accent-color);
}

.welcome-title {
  font-size: 32px;
  font-weight: 600;
  margin-bottom: 40px;
  color: var(--text-primary);
}

.suggestions-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  max-width: 600px;
  width: 100%;
}

.suggestion-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  padding: 16px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: left;
}

.suggestion-card:hover {
  background: var(--bg-hover);
  border-color: var(--accent-color);
  transform: translateY(-2px);
}

.suggestion-icon {
  font-size: 20px;
}

.suggestion-text {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* Messages */
.messages-container {
  max-width: 768px;
  margin: 0 auto;
  padding-bottom: 100px;
}

.message {
  display: flex;
  gap: 16px;
  padding: 24px 0;
  animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

.message-avatar {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-weight: 600;
  font-size: 14px;
}

.message.user .message-avatar {
  background: var(--accent-color);
  color: white;
}

.message.ai .message-avatar {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.message-content {
  flex: 1;
  min-width: 0;
}

.message-role {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.message-text {
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-primary);
}

.message-text p {
  margin-bottom: 12px;
}

.message-text p:last-child {
  margin-bottom: 0;
}

.message-text code {
  background: var(--bg-tertiary);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--accent-color);
}

.message-text pre {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 16px;
  overflow-x: auto;
  margin: 12px 0;
}

.message-text pre code {
  background: transparent;
  padding: 0;
  color: var(--text-primary);
  font-size: 13px;
  line-height: 1.6;
}

.message-text ul, .message-text ol {
  margin: 12px 0;
  padding-left: 24px;
}

.message-text li {
  margin-bottom: 6px;
}

.message-text strong {
  font-weight: 600;
  color: var(--text-primary);
}

.message-text em {
  font-style: italic;
  color: var(--text-secondary);
}

.message-actions {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.message:hover .message-actions {
  opacity: 1;
}

.msg-action-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  font-size: 13px;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.msg-action-btn:hover {
  background: var(--bg-tertiary);
  color: var(--text-primary);
}

/* Typing Indicator */
.typing-indicator {
  display: flex;
  gap: 4px;
  padding: 8px 0;
}

.typing-dot {
  width: 8px;
  height: 8px;
  background: var(--text-muted);
  border-radius: 50%;
  animation: typingBounce 1.4s infinite ease-in-out;
}

.typing-dot:nth-child(2) { animation-delay: 0.2s; }
.typing-dot:nth-child(3) { animation-delay: 0.4s; }

@keyframes typingBounce {
  0%, 60%, 100% { transform: translateY(0); }
  30% { transform: translateY(-8px); }
}

/* Input Area */
.input-area {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 16px 20px 24px;
  background: linear-gradient(to top, var(--bg-primary) 60%, transparent);
}

.input-wrapper {
  max-width: 768px;
  margin: 0 auto;
}

.input-container {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 12px 16px;
  transition: all var(--transition-fast);
}

.input-container:focus-within {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 2px rgba(16, 163, 127, 0.2);
}

#messageInput {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-size: 15px;
  line-height: 1.5;
  resize: none;
  outline: none;
  max-height: 200px;
  font-family: var(--font-sans);
}

#messageInput::placeholder {
  color: var(--text-muted);
}

.send-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-color);
  border: none;
  border-radius: var(--radius-sm);
  color: white;
  cursor: pointer;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.send-btn:hover:not(:disabled) {
  background: var(--accent-hover);
  transform: scale(1.05);
}

.send-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.input-footer {
  text-align: center;
  margin-top: 8px;
}

.input-hint {
  font-size: 12px;
  color: var(--text-muted);
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--bg-hover);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--bg-active);
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    transform: translateX(-100%);
    box-shadow: var(--shadow-lg);
  }

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

  .mobile-menu-btn {
    display: flex;
  }

  .suggestions-grid {
    grid-template-columns: 1fr;
  }

  .welcome-title {
    font-size: 24px;
  }

  .message {
    padding: 16px 0;
  }
}

@media (max-width: 480px) {
  .chat-area {
    padding: 12px;
  }

  .input-area {
    padding: 12px 12px 16px;
  }

  .suggestion-card {
    padding: 12px;
  }
}

/* Overlay for mobile sidebar */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 99;
}

.sidebar-overlay.active {
  display: block;
}