/* AI Chat Platform - Variables & Theme */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
  /* Colors - Modern Black & Gray with Blue Accent */
  --bg-primary: #0a0a0a;
  --bg-secondary: #141414;
  --bg-tertiary: #1c1c1c;
  --bg-elevated: #242424;
  --bg-hover: #2a2a2a;
  --bg-active: #323232;
  
  --text-primary: #f5f5f5;
  --text-secondary: #b0b0b0;
  --text-tertiary: #707070;
  --text-muted: #505050;
  --text-placeholder: #3a3a3a;
  
  --border-subtle: #1a1a1a;
  --border-default: #2a2a2a;
  --border-strong: #3a3a3a;
  
  /* Modern Blue Accent */
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-active: #1d4ed8;
  --accent-glow: rgba(59, 130, 246, 0.15);
  
  /* Gradient */
  --gradient-primary: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
  --gradient-bg: radial-gradient(ellipse at top, #1a1a2e 0%, #0a0a0a 100%);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.6);
  --shadow-glow: 0 0 30px rgba(59, 130, 246, 0.1);
  
  --radius-xs: 4px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;
  
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
  --transition-slow: 0.4s ease;
  
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', Consolas, monospace;
  
  --sidebar-width: 280px;
  --header-height: 64px;
}

/* Dark Theme (Default) */
[data-theme="dark"] {
  --bg-primary: #0a0a0a;
  --text-primary: #f5f5f5;
}

/* Light Theme */
[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-elevated: #ffffff;
  --bg-hover: #e2e8f0;
  --bg-active: #cbd5e1;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-tertiary: #64748b;
  --text-muted: #94a3b8;
  --text-placeholder: #cbd5e1;
  
  --border-subtle: #e2e8f0;
  --border-default: #cbd5e1;
  --border-strong: #94a3b8;
  
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-active: #1d4ed8;
  --accent-glow: rgba(59, 130, 246, 0.1);
  
  --gradient-bg: linear-gradient(180deg, #f8fafc 0%, #e2e8f0 100%);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 20px rgba(59, 130, 246, 0.08);
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

/* Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

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

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

::-webkit-scrollbar-thumb:hover {
  background: var(--border-strong);
}

/* Selection */
::selection {
  background: var(--accent);
  color: var(--text-primary);
}

/* Focus */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.3;
  color: var(--text-primary);
}

p {
  color: var(--text-secondary);
}

a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--text-primary);
}

/* Buttons */
button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  font-size: 0.875rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.btn-primary {
  background: var(--accent);
  color: white;
  border: none;
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.25);
}

.btn-primary:hover {
  background: var(--accent-hover);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.35);
}

.btn-primary:active {
  background: var(--accent-active);
  transform: scale(0.98);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: var(--radius-md);
  background: var(--bg-tertiary);
  border: 1px solid var(--border-default);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

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

/* Inputs */
input, textarea {
  font-family: inherit;
  font-size: 0.9375rem;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  padding: 12px 16px;
  transition: all var(--transition-fast);
}

input::placeholder, textarea::placeholder {
  color: var(--text-placeholder);
}

input:focus, textarea:focus {
  outline: none;
  border-color: var(--border-strong);
  background: var(--bg-hover);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

/* App Layout */
.app-container {
  display: flex;
  min-height: 100vh;
  background: var(--gradient-bg);
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  transition: transform var(--transition-normal);
}

.sidebar-header {
  padding: 24px;
  border-bottom: 1px solid var(--border-subtle);
}

.sidebar-logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.sidebar-logo-icon {
  width: 36px;
  height: 36px;
  background: var(--gradient-primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.3);
}

.sidebar-logo-icon svg {
  width: 20px;
  height: 20px;
  color: var(--text-primary);
}

.sidebar-logo-text {
  font-size: 1.125rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.sidebar-nav {
  flex: 1;
  padding: 16px 12px;
  overflow-y: auto;
}

.nav-section {
  margin-bottom: 24px;
}

.nav-section-title {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  padding: 8px 12px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: 0.9375rem;
  font-weight: 450;
  transition: all var(--transition-fast);
  margin-bottom: 2px;
}

.nav-item:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.nav-item.active {
  background: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1px solid var(--border-default);
}

.nav-item svg {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  opacity: 0.7;
}

.nav-item.active svg {
  opacity: 1;
}

.nav-badge {
  margin-left: auto;
  background: var(--bg-elevated);
  padding: 2px 8px;
  border-radius: var(--radius-full);
  font-size: 0.6875rem;
  font-weight: 600;
  color: var(--text-tertiary);
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* Chat Container */
.chat-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  max-height: 100vh;
}

.chat-header {
  height: var(--header-height);
  padding: 0 32px;
  border-bottom: 1px solid var(--border-subtle);
  background: var(--bg-secondary);
  display: flex;
  align-items: center;
  justify-content: space-between;
  backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 50;
}

.chat-header-title {
  display: flex;
  align-items: center;
  gap: 12px;
}

.chat-header-title h2 {
  font-size: 1rem;
  font-weight: 600;
}

.chat-status {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8125rem;
  color: var(--text-tertiary);
}

.chat-status-dot {
  width: 8px;
  height: 8px;
  background: #22c55e;
  border-radius: 50%;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}

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

/* Messages */
.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 24px 32px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.message {
  max-width: 75%;
  display: flex;
  gap: 12px;
  animation: messageIn 0.3s ease;
}

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

.message.user {
  flex-direction: row-reverse;
  align-self: flex-end;
}

.message-avatar {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background: var(--bg-tertiary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.message.assistant .message-avatar {
  background: var(--gradient-primary);
}

.message-avatar svg {
  width: 16px;
  height: 16px;
  color: var(--text-primary);
}

.message-content {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
  padding: 14px 18px;
}

.message.user .message-content {
  background: var(--bg-elevated);
  border-color: var(--border-strong);
}

.message-text {
  font-size: 0.9375rem;
  line-height: 1.6;
  color: var(--text-primary);
  word-wrap: break-word;
}

.message-time {
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 6px;
}

/* Input Area */
.input-area {
  padding: 20px 32px 28px;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
}

.input-wrapper {
  display: flex;
  gap: 12px;
  align-items: flex-end;
  max-width: 800px;
  margin: 0 auto;
}

.input-field {
  flex: 1;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-lg);
  padding: 14px 18px;
  color: var(--text-primary);
  font-size: 0.9375rem;
  resize: none;
  min-height: 52px;
  max-height: 160px;
  line-height: 1.5;
  transition: all var(--transition-fast);
}

.input-field:focus {
  outline: none;
  border-color: var(--border-strong);
  background: var(--bg-hover);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.send-btn {
  padding: 14px 24px;
  background: var(--gradient-primary);
  border: none;
  border-radius: var(--radius-lg);
  color: white;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 8px;
  box-shadow: 0 2px 12px rgba(59, 130, 246, 0.3);
}

.send-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(59, 130, 246, 0.4);
}

.send-btn:active {
  transform: translateY(0);
}

.send-btn svg {
  width: 18px;
  height: 18px;
}

/* Typing Indicator */
.typing-indicator {
  display: flex;
  gap: 4px;
  padding: 12px 16px;
}

.typing-indicator span {
  width: 8px;
  height: 8px;
  background: var(--text-tertiary);
  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; }
.typing-indicator span:nth-child(3) { animation-delay: 0s; }

@keyframes bounce {
  0%, 80%, 100% { 
    transform: scale(0.6); 
    opacity: 0.5; 
  }
  40% { 
    transform: scale(1); 
    opacity: 1; 
  }
}

/* Mobile Menu Button */
.mobile-menu-btn {
  display: none;
  position: fixed;
  top: 16px;
  left: 16px;
  z-index: 1000;
  width: 44px;
  height: 44px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

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

.mobile-menu-btn svg {
  width: 22px;
  height: 22px;
}

/* Overlay */
.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 99;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.overlay.active {
  opacity: 1;
}

/* Mobile Responsive */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
  }
  
  .sidebar.open {
    transform: translateX(0);
  }
  
  .mobile-menu-btn {
    display: flex;
  }
  
  .overlay.active {
    display: block;
  }
  
  .main-content {
    margin-left: 0;
  }
  
  .chat-header {
    padding: 0 16px;
    padding-left: 68px;
  }
  
  .chat-messages {
    padding: 16px;
    gap: 16px;
  }
  
  .message {
    max-width: 90%;
  }
  
  .input-area {
    padding: 16px;
  }
  
  .input-wrapper {
    flex-direction: column;
  }
  
  .send-btn {
    width: 100%;
    justify-content: center;
  }
}

/* Utility Classes */
.hidden { display: none !important; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-1 { gap: 4px; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.gap-4 { gap: 16px; }
.p-2 { padding: 8px; }
.p-4 { padding: 16px; }
.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.text-sm { font-size: 0.875rem; }
.text-xs { font-size: 0.75rem; }
.text-muted { color: var(--text-muted); }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }

/* Welcome Screen */
.welcome-screen {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 40px;
}

.welcome-icon {
  width: 72px;
  height: 72px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-default);
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 24px;
}

.welcome-icon svg {
  width: 36px;
  height: 36px;
  color: var(--text-primary);
}

.welcome-title {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.welcome-text {
  color: var(--text-secondary);
  max-width: 400px;
}

/* Empty State */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 60px 20px;
  text-align: center;
}

.empty-state svg {
  width: 48px;
  height: 48px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.empty-state h3 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.empty-state p {
  font-size: 0.875rem;
  color: var(--text-muted);
}