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

:root {
  --bg-primary: #343541;
  --bg-secondary: #444654;
  --bg-tertiary: #202123;
  --text-primary: #ececf1;
  --text-secondary: #c5c5d2;
  --border-color: #565869;
  --accent-color: #10a37f;
  --accent-hover: #0d8c6d;
  --error-color: #ef4444;
  --user-msg-bg: #343541;
  --assistant-msg-bg: #444654;
}

body.light-theme {
  --bg-primary: #ffffff;
  --bg-secondary: #f7f7f8;
  --bg-tertiary: #ececf1;
  --text-primary: #000000;
  --text-secondary: #565869;
  --border-color: #d1d5db;
  --user-msg-bg: #ffffff;
  --assistant-msg-bg: #f7f7f8;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  height: 100vh;
  overflow: hidden;
}

.login-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  background: linear-gradient(135deg, var(--bg-tertiary) 0%, var(--bg-primary) 100%);
}

.login-box {
  background: var(--bg-secondary);
  padding: 2.5rem;
  border-radius: 12px;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
  width: 100%;
  max-width: 400px;
  border: 1px solid var(--border-color);
}

.login-header {
  text-align: center;
  margin-bottom: 2rem;
}

.logo {
  margin-bottom: 1rem;
}

.login-header h1 {
  font-size: 1.75rem;
  margin-bottom: 0.5rem;
}

.login-header p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  font-size: 0.9rem;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: var(--bg-primary);
  color: var(--text-primary);
  font-size: 0.95rem;
  transition: border-color 0.2s;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--accent-color);
}

.form-group textarea {
  resize: vertical;
  font-family: inherit;
}

.btn-primary {
  width: 100%;
  padding: 0.875rem;
  background: var(--accent-color);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

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

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

.error-message {
  color: var(--error-color);
  font-size: 0.875rem;
  margin-top: 1rem;
  text-align: center;
}

.main-container {
  display: flex;
  height: 100vh;
  position: relative;
}

.sidebar {
  width: 260px;
  background: var(--bg-tertiary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  transition: transform 0.3s ease;
}

.sidebar-header {
  padding: 0.75rem;
  border-bottom: 1px solid var(--border-color);
}

.btn-new-chat {
  width: 100%;
  padding: 0.75rem;
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  transition: background 0.2s;
}

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

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

.chat-item {
  padding: 0.75rem;
  margin-bottom: 0.25rem;
  border-radius: 6px;
  cursor: pointer;
  color: var(--text-primary);
  font-size: 0.9rem;
  transition: background 0.2s;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

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

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

.chat-item-delete {
  margin-left: auto;
  opacity: 0;
  color: var(--text-secondary);
  padding: 0.25rem;
  background: transparent;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
}

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

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

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

.sidebar-item {
  width: 100%;
  padding: 0.75rem;
  background: transparent;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  border-radius: 6px;
  transition: background 0.2s;
}

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

.mobile-menu-toggle {
  display: none;
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 100;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.5rem;
  border-radius: 6px;
  cursor: pointer;
}

.chat-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.messages-container {
  flex: 1;
  overflow-y: auto;
  scroll-behavior: smooth;
}

.welcome-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  text-align: center;
  padding: 2rem;
}

.welcome-logo {
  margin-bottom: 1.5rem;
  opacity: 0.8;
}

.welcome-screen h2 {
  font-size: 1.5rem;
  color: var(--text-secondary);
}

#messages {
  padding: 1rem 0;
}

.message {
  padding: 1.5rem;
  display: flex;
  gap: 1.5rem;
  max-width: 48rem;
  margin: 0 auto;
}

.message.user {
  background: var(--user-msg-bg);
}

.message.assistant {
  background: var(--assistant-msg-bg);
}

.message-avatar {
  width: 32px;
  height: 32px;
  border-radius: 4px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.9rem;
}

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

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

.message-content {
  flex: 1;
  line-height: 1.6;
  overflow-wrap: break-word;
}

.message-content p {
  margin-bottom: 1rem;
}

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

.message-content pre {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 1rem;
  overflow-x: auto;
  margin: 1rem 0;
}

.message-content code {
  background: var(--bg-tertiary);
  padding: 0.2rem 0.4rem;
  border-radius: 3px;
  font-size: 0.9em;
  font-family: 'Courier New', monospace;
}

.message-content pre code {
  background: transparent;
  padding: 0;
}

.message-content ul,
.message-content ol {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

.message-content li {
  margin-bottom: 0.5rem;
}

.input-container {
  padding: 1rem;
  border-top: 1px solid var(--border-color);
  background: var(--bg-primary);
}

.message-form {
  max-width: 48rem;
  margin: 0 auto;
  display: flex;
  gap: 0.75rem;
  align-items: flex-end;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 0.75rem 1rem;
}

#message-input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-size: 1rem;
  resize: none;
  max-height: 200px;
  font-family: inherit;
  line-height: 1.5;
}

#message-input:focus {
  outline: none;
}

.send-btn {
  background: var(--accent-color);
  border: none;
  color: white;
  width: 36px;
  height: 36px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s;
  flex-shrink: 0;
}

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

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

.attach-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  width: 36px;
  height: 36px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, color 0.2s;
  flex-shrink: 0;
}

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

.file-preview-container {
  max-width: 48rem;
  margin: 0 auto 0.75rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.file-preview {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.5rem 0.75rem;
  font-size: 0.875rem;
}

.file-preview-name {
  color: var(--text-primary);
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.file-preview-size {
  color: var(--text-secondary);
  font-size: 0.75rem;
}

.file-preview-remove {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 0.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 4px;
  transition: background 0.2s, color 0.2s;
}

.file-preview-remove:hover {
  background: var(--bg-primary);
  color: var(--error-color);
}

.file-attachment {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  margin: 0.5rem 0;
  font-size: 0.875rem;
  color: var(--text-primary);
}

.file-attachment svg {
  flex-shrink: 0;
}

.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--bg-secondary);
  border-radius: 12px;
  width: 90%;
  max-width: 500px;
  max-height: 90vh;
  overflow-y: auto;
  border: 1px solid var(--border-color);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
  font-size: 1.5rem;
}

.modal-close {
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-size: 2rem;
  cursor: pointer;
  line-height: 1;
  padding: 0;
  width: 32px;
  height: 32px;
}

.modal-body {
  padding: 1.5rem;
}

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

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

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

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

@keyframes typing {
  0%, 60%, 100% {
    opacity: 0.3;
    transform: translateY(0);
  }
  30% {
    opacity: 1;
    transform: translateY(-10px);
  }
}

@media (max-width: 768px) {
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    height: 100vh;
    z-index: 99;
    transform: translateX(-100%);
  }

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

  .mobile-menu-toggle {
    display: block;
  }

  .message {
    padding: 1rem;
    gap: 1rem;
  }

  .input-container {
    padding: 0.75rem;
  }
}

::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}