/* ===== CSS Custom Properties ===== */
:root {
  /* Colors */
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --accent: #8b5cf6;
  --background: #fafaf9;
  --surface: #ffffff;
  --text-primary: #111111;
  --text-secondary: #444444;
  --text-muted: #666666;
  --border: #e5e5e5;
  --success: #10b981;
  --error: #ef4444;
  --warning: #f59e0b;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
  
  /* Typography */
  --font-heading: 'Syne', sans-serif;
  --font-body: 'DM Sans', sans-serif;
  
  /* Spacing */
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  
  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
  
  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 300ms ease;
}

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

html {
  scroll-behavior: smooth;
}

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

/* ===== Utility Classes ===== */
.gradient-text {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-xs);
  padding: 0.75rem 1.5rem;
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.btn-secondary {
  background: var(--surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--background);
  border-color: var(--primary);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
}

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  padding: var(--space-sm) 0;
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 var(--space-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.nav-cta {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.mobile-menu-btn span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  transition: all var(--transition-fast);
}

/* ===== Chat Section (Full Screen) ===== */
.chat-section {
  padding: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--surface);
}

.chat-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  max-width: 100%;
  margin: 0;
  border-radius: 0;
  box-shadow: none;
  height: 100%;
  min-height: auto;
}

.chat-header {
  padding: var(--space-md) var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: var(--surface);
  flex-shrink: 0;
}

.chat-header h2 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
}

.chat-status {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: 0.875rem;
  color: var(--text-muted);
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--success);
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-lg);
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  scroll-behavior: smooth;
}

.message {
  display: flex;
  gap: var(--space-sm);
  max-width: 85%;
  animation: messageIn 0.3s ease;
}

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

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

.bot-message {
  align-self: flex-start;
}

.message-avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  flex-shrink: 0;
}

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

.bot-message .message-avatar {
  background: var(--surface);
  border: 1px solid var(--border);
}

.message-content {
  background: var(--surface);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  position: relative;
}

.user-message .message-content {
  background: var(--gradient-primary);
  color: white;
}

.message-content p {
  margin: 0;
  line-height: 1.6;
  white-space: pre-wrap;
  word-wrap: break-word;
}

.message-time {
  display: block;
  font-size: 0.75rem;
  margin-top: var(--space-xs);
  opacity: 0.7;
}

.user-message .message-time {
  text-align: right;
  color: rgba(255, 255, 255, 0.8);
}

.typing-indicator {
  display: flex;
  gap: 4px;
  padding: var(--space-sm);
}

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

.typing-indicator span:nth-child(1) { animation-delay: 0s; }
.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }

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

.chat-input-area {
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border);
  background: var(--surface);
  flex-shrink: 0;
}

.input-wrapper {
  display: flex;
  gap: var(--space-sm);
  align-items: flex-end;
}

#messageInput {
  flex: 1;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  font-family: var(--font-body);
  font-size: 1rem;
  resize: none;
  max-height: 150px;
  min-height: 48px;
  transition: border-color var(--transition-fast);
  line-height: 1.5;
}

#messageInput:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.send-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--gradient-primary);
  color: white;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-base);
  flex-shrink: 0;
}

.send-btn:hover:not(:disabled) {
  transform: scale(1.05);
  box-shadow: var(--shadow-lg);
}

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

.input-footer {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-xs);
  font-size: 0.875rem;
  color: var(--text-muted);
}

.model-info {
  font-weight: 500;
  color: var(--primary);
}

/* ===== Modal ===== */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: var(--space-md);
}

.modal.active {
  display: flex;
}

.modal-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
}

.modal-content {
  position: relative;
  background: var(--surface);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  width: 100%;
  max-width: 500px;
  max-height: 90vh;
  overflow-y: auto;
  animation: modalIn 0.3s ease;
}

@keyframes modalIn {
  from {
    opacity: 0;
    transform: scale(0.95) translateY(20px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

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

.modal-header h3 {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
}

.modal-close {
  background: none;
  border: none;
  font-size: 2rem;
  cursor: pointer;
  color: var(--text-muted);
  line-height: 1;
  padding: 0;
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: all var(--transition-fast);
}

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

.modal-body {
  padding: var(--space-lg);
}

.setting-group {
  margin-bottom: var(--space-lg);
}

.setting-group:last-child {
  margin-bottom: 0;
}

.setting-group label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.input-with-button {
  display: flex;
  gap: var(--space-sm);
}

.input-with-button input {
  flex: 1;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: 1rem;
}

.input-with-button input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.setting-description {
  margin-top: var(--space-xs);
  font-size: 0.875rem;
  color: var(--text-muted);
}

.setting-description a {
  color: var(--primary);
  text-decoration: none;
}

.setting-description a:hover {
  text-decoration: underline;
}

select {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: 1rem;
  background: var(--surface);
  cursor: pointer;
}

select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.button-group {
  display: flex;
  gap: var(--space-sm);
}

.modal-footer {
  padding: var(--space-lg);
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: flex-end;
}

/* ===== Loading Overlay ===== */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255, 255, 255, 0.9);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 3000;
  backdrop-filter: blur(4px);
}

.loading-overlay.active {
  display: flex;
}

.spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: var(--space-md);
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-overlay p {
  font-weight: 600;
  color: var(--text-secondary);
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
  .nav-links {
    position: fixed;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--surface);
    flex-direction: column;
    padding: var(--space-lg);
    gap: var(--space-md);
    border-bottom: 1px solid var(--border);
    transform: translateY(-100%);
    opacity: 0;
    transition: all var(--transition-base);
    pointer-events: none;
  }

  .nav-links.active {
    transform: translateY(0);
    opacity: 1;
    pointer-events: all;
  }

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

  .mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }

  .mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
  }

  .mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }

  .chat-header h2 {
    font-size: 1.125rem;
  }

  .message-avatar {
    width: 32px;
    height: 32px;
    font-size: 0.875rem;
  }

  .message-content {
    padding: var(--space-xs) var(--space-sm);
  }
}

@media (max-width: 480px) {
  .input-with-button {
    flex-direction: column;
  }

  .input-with-button button {
    width: 100%;
  }

  .message {
    max-width: 95%;
  }
}

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

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

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

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

/* ===== Selection ===== */
::selection {
  background: rgba(99, 102, 241, 0.2);
  color: var(--text-primary);
}