:root {
  --bg-primary: #0f0f0f;
  --bg-secondary: #1a1a1a;
  --bg-tertiary: #252525;
  --bg-hover: #2a2a2a;
  --bg-input: #1e1e1e;
  --text-primary: #ececec;
  --text-secondary: #a0a0a0;
  --text-muted: #6b6b6b;
  --accent: #8b5cf6;
  --accent-hover: #7c3aed;
  --accent-soft: rgba(139, 92, 246, 0.15);
  --border: #333333;
  --success: #22c55e;
  --danger: #ef4444;
  --warning: #f59e0b;
  --user-bubble: #2d2d2d;
  --assistant-bubble: transparent;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --radius: 12px;
  --radius-sm: 8px;
  --sidebar-width: 280px;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

[data-theme="light"] {
  --bg-primary: #f7f7f8;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f0f0f0;
  --bg-hover: #e8e8e8;
  --bg-input: #ffffff;
  --text-primary: #1a1a1a;
  --text-secondary: #4a4a4a;
  --text-muted: #8a8a8a;
  --accent: #7c3aed;
  --accent-hover: #6d28d9;
  --accent-soft: rgba(124, 58, 237, 0.1);
  --border: #e0e0e0;
  --user-bubble: #e8e0ff;
  --assistant-bubble: transparent;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.08);
}

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

html, body {
  height: 100%;
  font-family: var(--font);
  background: var(--bg-primary);
  color: var(--text-primary);
  overflow: hidden;
}

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--text-muted);
  border-radius: 3px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}

/* Layout */
.app {
  display: flex;
  height: 100vh;
  width: 100vw;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  transition: transform 0.25s ease, width 0.25s ease;
  z-index: 100;
}

.sidebar.collapsed {
  transform: translateX(-100%);
  position: absolute;
  height: 100%;
}

.sidebar-header {
  padding: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border);
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.5px;
  color: var(--text-primary);
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  color: white;
  font-weight: 800;
}

.btn-new-chat {
  width: 100%;
  margin: 12px 16px;
  padding: 12px 16px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: background 0.2s;
}

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

.chat-list {
  flex: 1;
  overflow-y: auto;
  padding: 8px 12px;
}

.chat-item {
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 4px;
  transition: background 0.15s;
  position: relative;
  group: true;
}

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

.chat-item.active {
  background: var(--accent-soft);
}

.chat-item-title {
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  font-size: 0.9rem;
  color: var(--text-primary);
}

.chat-item-delete {
  opacity: 0;
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px;
  border-radius: 4px;
  transition: opacity 0.15s, color 0.15s;
}

.chat-item:hover .chat-item-delete {
  opacity: 1;
}

.chat-item-delete:hover {
  color: var(--danger);
}

.sidebar-footer {
  padding: 12px 16px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.sidebar-btn {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  width: 100%;
  text-align: left;
}

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

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

.main-header {
  height: 56px;
  display: flex;
  align-items: center;
  padding: 0 16px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-primary);
  gap: 12px;
}

.btn-toggle-sidebar {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 8px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.model-badge {
  font-size: 0.85rem;
  color: var(--text-secondary);
  background: var(--bg-tertiary);
  padding: 4px 10px;
  border-radius: 20px;
  margin-left: auto;
}

/* Chat area */
.chat-container {
  flex: 1;
  overflow-y: auto;
  padding: 24px 0;
  scroll-behavior: smooth;
}

.chat-messages {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

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

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.message-avatar {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 14px;
  flex-shrink: 0;
}

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

.message.assistant .message-avatar {
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  color: white;
}

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

.message-role {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.message-text {
  line-height: 1.65;
  font-size: 0.975rem;
  color: var(--text-primary);
  word-wrap: break-word;
}

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

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

.message-text ul, .message-text ol {
  margin: 8px 0 12px 20px;
}

.message-text li {
  margin-bottom: 4px;
}

.message-text code {
  background: var(--bg-tertiary);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.88em;
}

.message-text pre {
  background: #1e1e1e;
  border-radius: var(--radius-sm);
  padding: 16px;
  overflow-x: auto;
  margin: 12px 0;
  position: relative;
}

[data-theme="light"] .message-text pre {
  background: #2d2d2d;
}

.message-text pre code {
  background: none;
  padding: 0;
  font-size: 0.9em;
  color: #e0e0e0;
}

.message-text blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 16px;
  margin: 12px 0;
  color: var(--text-secondary);
}

.message-text table {
  border-collapse: collapse;
  width: 100%;
  margin: 12px 0;
}

.message-text th, .message-text td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}

.message-text th {
  background: var(--bg-tertiary);
}

.message-actions {
  display: flex;
  gap: 8px;
  margin-top: 10px;
  opacity: 0;
  transition: opacity 0.15s;
}

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

.msg-action-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 0.8rem;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: background 0.15s, color 0.15s;
}

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

/* Empty state */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
  padding: 40px 20px;
  color: var(--text-secondary);
}

.empty-state h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  background: linear-gradient(135deg, #8b5cf6, #ec4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.empty-state p {
  font-size: 1.05rem;
  max-width: 420px;
  margin-bottom: 32px;
}

.suggestions {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  max-width: 640px;
  width: 100%;
}

.suggestion-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  cursor: pointer;
  text-align: left;
  transition: border-color 0.2s, background 0.2s;
  font-size: 0.9rem;
  color: var(--text-primary);
}

.suggestion-card:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

/* Input area */
.input-area {
  padding: 16px 24px 24px;
  background: var(--bg-primary);
  border-top: 1px solid var(--border);
}

.input-wrapper {
  max-width: 800px;
  margin: 0 auto;
  position: relative;
}

.input-box {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.input-box:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.input-row {
  display: flex;
  align-items: flex-end;
  gap: 8px;
}

#user-input {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.975rem;
  line-height: 1.5;
  resize: none;
  max-height: 200px;
  min-height: 24px;
  padding: 4px 0;
}

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

.input-actions {
  display: flex;
  align-items: center;
  gap: 4px;
}

.btn-icon {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 8px;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s, color 0.15s;
}

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

.btn-send {
  background: var(--accent);
  color: white;
  border: none;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, opacity 0.2s;
}

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

.btn-send:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.file-preview {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding-top: 4px;
}

.file-chip {
  display: flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-tertiary);
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.file-chip img {
  width: 24px;
  height: 24px;
  border-radius: 4px;
  object-fit: cover;
}

.file-chip button {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0;
  font-size: 14px;
}

.input-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 8px;
  font-size: 0.75rem;
  color: var(--text-muted);
  padding: 0 4px;
}

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

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

.typing-indicator span:nth-child(1) { animation-delay: -0.32s; }
.typing-indicator span:nth-child(2) { animation-delay: -0.16s; }

@keyframes bounce {
  0%, 80%, 100% { transform: scale(0); }
  40% { transform: scale(1); }
}

/* Modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s, visibility 0.2s;
}

.modal-overlay.open {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 16px;
  width: 90%;
  max-width: 560px;
  max-height: 85vh;
  overflow-y: auto;
  box-shadow: var(--shadow);
  transform: scale(0.95);
  transition: transform 0.2s;
}

.modal-overlay.open .modal {
  transform: scale(1);
}

.modal-header {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-header h2 {
  font-size: 1.2rem;
  font-weight: 600;
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 6px;
  border-radius: 6px;
  font-size: 1.2rem;
}

.modal-close:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.modal-body {
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-group label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.form-group input,
.form-group select,
.form-group textarea {
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 0.95rem;
  outline: none;
  transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--accent);
}

.form-group textarea {
  min-height: 120px;
  resize: vertical;
  line-height: 1.5;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.modal-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: flex-end;
  gap: 12px;
}

.btn {
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: background 0.2s, opacity 0.2s;
}

.btn-primary {
  background: var(--accent);
  color: white;
}

.btn-primary:hover {
  background: var(--accent-hover);
}

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

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

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--bg-tertiary);
  color: var(--text-primary);
  padding: 12px 20px;
  border-radius: 10px;
  font-size: 0.9rem;
  box-shadow: var(--shadow);
  z-index: 2000;
  transition: transform 0.3s ease;
  border: 1px solid var(--border);
}

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

/* Mobile */
@media (max-width: 768px) {
  .sidebar {
    position: absolute;
    height: 100%;
    transform: translateX(-100%);
  }

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

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

  .chat-messages {
    padding: 0 16px;
  }

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

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

  .form-row {
    grid-template-columns: 1fr;
  }
}

/* Code copy button */
.code-block-wrapper {
  position: relative;
}

.code-copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  background: rgba(255,255,255,0.1);
  border: none;
  color: #ccc;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 0.75rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
}

.code-block-wrapper:hover .code-copy-btn {
  opacity: 1;
}

.code-copy-btn:hover {
  background: rgba(255,255,255,0.2);
}