/*
 * TickChat Design System
 * Phase 1: semantic foundations only. Component migrations follow in order.
 */
:root {
  /* Type families */
  --tc-font-sans: "Inter", "Cairo", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --tc-font-arabic: "Cairo", "Noto Sans Arabic", Tahoma, sans-serif;
  --tc-font-mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;

  /* Modular type scale */
  --tc-type-2xs: 0.6875rem;
  --tc-type-xs: 0.75rem;
  --tc-type-sm: 0.875rem;
  --tc-type-md: 1rem;
  --tc-type-lg: 1.125rem;
  --tc-type-xl: 1.375rem;
  --tc-type-2xl: 1.75rem;
  --tc-leading-tight: 1.25;
  --tc-leading-normal: 1.55;
  --tc-leading-reading: 1.75;

  /* Four-pixel spacing scale */
  --tc-space-0: 0;
  --tc-space-1: 0.25rem;
  --tc-space-2: 0.5rem;
  --tc-space-3: 0.75rem;
  --tc-space-4: 1rem;
  --tc-space-5: 1.25rem;
  --tc-space-6: 1.5rem;
  --tc-space-8: 2rem;
  --tc-space-10: 2.5rem;
  --tc-space-12: 3rem;
  --tc-space-16: 4rem;

  /* Shape */
  --tc-radius-xs: 0.375rem;
  --tc-radius-sm: 0.5rem;
  --tc-radius-md: 0.75rem;
  --tc-radius-lg: 1rem;
  --tc-radius-xl: 1.25rem;
  --tc-radius-pill: 999px;

  /* Light theme: semantic color roles */
  --tc-canvas: #ffffff;
  --tc-sidebar: #f6f7f8;
  --tc-surface: #ffffff;
  --tc-surface-subtle: #f2f4f6;
  --tc-surface-hover: #e9ecef;
  --tc-surface-active: #e3e7eb;
  --tc-text: #191b20;
  --tc-text-secondary: #5c626c;
  --tc-text-tertiary: #7d8490;
  --tc-border: #e1e4e8;
  --tc-border-strong: #cfd4da;
  --tc-accent: #315fda;
  --tc-accent-hover: #284fb9;
  --tc-accent-soft: #edf2ff;
  --tc-on-accent: #ffffff;
  --tc-success: #18794e;
  --tc-success-soft: #eaf7f0;
  --tc-warning: #9a5b13;
  --tc-warning-soft: #fff5e5;
  --tc-danger: #c63737;
  --tc-danger-soft: #fff0f0;
  --tc-code-surface: #11141a;
  --tc-code-text: #e8ebf1;
  --tc-overlay: rgba(10, 12, 16, 0.48);

  /* Elevation */
  --tc-shadow-xs: 0 1px 2px rgba(17, 24, 39, 0.05);
  --tc-shadow-sm: 0 4px 14px rgba(17, 24, 39, 0.07);
  --tc-shadow-md: 0 12px 32px rgba(17, 24, 39, 0.10);
  --tc-focus-ring: 0 0 0 3px rgba(49, 95, 218, 0.22);

  /* Motion */
  --tc-ease-standard: cubic-bezier(0.2, 0.8, 0.2, 1);
  --tc-duration-fast: 120ms;
  --tc-duration-normal: 180ms;

  /* Layout */
  --tc-sidebar-width: 17rem;
  --tc-reading-width: 48rem;
  --tc-composer-width: 50rem;
  --tc-control-height: 2.5rem;
  --tc-safe-bottom: max(var(--tc-space-3), env(safe-area-inset-bottom));

  /* Compatibility aliases for existing components during migration */
  --primary: var(--tc-accent);
  --primary-light: #5079e4;
  --primary-dark: var(--tc-accent-hover);
  --primary-glow: rgba(49, 95, 218, 0.12);
  --surface: var(--tc-surface);
  --surface-2: var(--tc-surface-subtle);
  --surface-3: var(--tc-surface-hover);
  --elevated: var(--tc-surface);
  --text: var(--tc-text);
  --text-2: var(--tc-text-secondary);
  --text-3: var(--tc-text-tertiary);
  --border: var(--tc-border);
  --border-2: var(--tc-border-strong);
  --sidebar-bg: var(--tc-sidebar);
  --chat-bg: var(--tc-canvas);
  --code-bg: var(--tc-code-surface);
  --success: var(--tc-success);
  --warning: var(--tc-warning);
  --danger: var(--tc-danger);
  --focus-ring: var(--tc-focus-ring);
  --font-ui: var(--tc-font-sans);
  --font-ar: var(--tc-font-arabic);
}

html.dark {
  --tc-canvas: #101114;
  --tc-sidebar: #15171b;
  --tc-surface: #1a1c21;
  --tc-surface-subtle: #202329;
  --tc-surface-hover: #282b32;
  --tc-surface-active: #30343c;
  --tc-text: #f1f3f5;
  --tc-text-secondary: #adb2bc;
  --tc-text-tertiary: #818894;
  --tc-border: rgba(255, 255, 255, 0.085);
  --tc-border-strong: rgba(255, 255, 255, 0.14);
  --tc-accent: #84a7ff;
  --tc-accent-hover: #9bb8ff;
  --tc-accent-soft: rgba(96, 137, 239, 0.14);
  --tc-on-accent: #101833;
  --tc-success: #69d3a4;
  --tc-success-soft: rgba(55, 185, 125, 0.13);
  --tc-warning: #e5b96a;
  --tc-warning-soft: rgba(210, 148, 48, 0.13);
  --tc-danger: #ff8585;
  --tc-danger-soft: rgba(225, 76, 76, 0.14);
  --tc-code-surface: #090b0f;
  --tc-code-text: #e8ebf1;
  --tc-overlay: rgba(0, 0, 0, 0.58);
  --tc-shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.28);
  --tc-shadow-sm: 0 5px 16px rgba(0, 0, 0, 0.30);
  --tc-shadow-md: 0 16px 40px rgba(0, 0, 0, 0.42);
  --tc-focus-ring: 0 0 0 3px rgba(132, 167, 255, 0.25);

  --primary: var(--tc-accent);
  --primary-light: #a8c0ff;
  --primary-dark: #7098fa;
  --primary-glow: rgba(132, 167, 255, 0.14);
}

/* Phase 2: typography */
html {
  font-family: var(--tc-font-sans);
  font-size: 16px;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  font-synthesis: none;
}

body.chat-app {
  color: var(--tc-text);
  font-family: var(--tc-font-sans);
  font-size: var(--tc-type-sm);
  line-height: var(--tc-leading-normal);
  letter-spacing: -0.006em;
}

body.chat-app :where(button, input, textarea, select) {
  font: inherit;
  letter-spacing: inherit;
}

body.chat-app :where(h1, h2, h3, h4, h5, h6) {
  color: var(--tc-text);
  font-weight: 650;
  line-height: var(--tc-leading-tight);
  letter-spacing: -0.02em;
  text-wrap: balance;
}

body.chat-app h1 { font-size: var(--tc-type-2xl); }
body.chat-app h2 { font-size: var(--tc-type-xl); }
body.chat-app h3 { font-size: var(--tc-type-lg); }

body.chat-app :where(.text-xs, .metadata, time, .sidebar-item-meta) {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-xs);
  line-height: 1.45;
}

body.chat-app :where(.sidebar-section-heading, .field-label, label > span:first-child) {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-2xs);
  font-weight: 650;
  line-height: 1.4;
  letter-spacing: 0.055em;
}

body.chat-app :where(.msg-rtl, [dir="rtl"], :lang(ar)) {
  font-family: var(--tc-font-arabic);
  letter-spacing: 0;
  font-feature-settings: normal;
}

body.chat-app :where(.msg-ltr, [dir="ltr"]) {
  font-family: var(--tc-font-sans);
}

body.chat-app :where(code, pre, kbd, samp) {
  font-family: var(--tc-font-mono);
  font-variant-ligatures: none;
}

body.chat-app .prose {
  color: var(--tc-text);
  font-size: 0.9375rem;
  line-height: var(--tc-leading-reading);
  text-wrap: pretty;
}

body.chat-app .prose :where(small, figcaption) {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-xs);
  line-height: var(--tc-leading-normal);
}

body.chat-app .prose :where(strong, b) { font-weight: 650; }
body.chat-app .prose :where(code, pre, table) { text-wrap: wrap; }
body.chat-app .prose pre { text-wrap: nowrap; }

@media (max-width: 430px) {
  html { font-size: 15px; }
  body.chat-app .prose { font-size: var(--tc-type-md); }
}

/* Phase 9: attachments */
body.chat-app #file-preview {
  background: var(--tc-surface) !important;
  border: 1px solid var(--tc-border) !important;
  border-radius: var(--tc-radius-lg) !important;
  box-shadow: var(--tc-shadow-sm) !important;
}

body.chat-app :where(.file-chip-container, .message-file-card, .attachment-card) {
  min-block-size: 2.75rem;
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-md);
  box-shadow: none;
}

body.chat-app :where(.file-chip-name, .message-file-name, .attachment-name) {
  min-inline-size: 0;
  overflow: hidden;
  color: var(--tc-text);
  font-size: var(--tc-type-xs);
  font-weight: 550;
  text-overflow: ellipsis;
  white-space: nowrap;
}

body.chat-app :where(.file-chip-meta, .message-file-meta, .attachment-meta) {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-2xs);
}

body.chat-app :where(.file-chip-remove, .attachment-remove) {
  display: inline-grid;
  inline-size: 1.75rem;
  block-size: 1.75rem;
  place-items: center;
  color: var(--tc-text-tertiary);
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-xs);
}

body.chat-app :where(.file-chip-remove, .attachment-remove):hover {
  color: var(--tc-danger);
  background: var(--tc-danger-soft);
}

body.chat-app :where(.file-chip-progress, .attachment-progress) {
  block-size: 2px;
  background: var(--tc-border);
  border-radius: var(--tc-radius-pill);
  overflow: hidden;
}

body.chat-app :where(.file-chip-progress-fill, .attachment-progress-fill) {
  block-size: 100%;
  background: var(--tc-accent);
  border-radius: inherit;
  transition: inline-size var(--tc-duration-normal) var(--tc-ease-standard);
}

body.chat-app .message-attachments { margin-block: var(--tc-space-3); gap: var(--tc-space-2); }
body.chat-app .message-attachments-images { gap: var(--tc-space-2); }

body.chat-app .message-attachment-image {
  max-inline-size: min(100%, 28rem);
  background: var(--tc-surface-subtle);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-md);
  box-shadow: none;
  overflow: hidden;
}

body.chat-app .message-attachment-image img {
  display: block;
  inline-size: 100%;
  block-size: auto;
  object-fit: contain;
}

body.chat-app .file-chip-attachment.adding .file-chip-container { opacity: 0; transform: translateY(4px); }
body.chat-app .file-chip-attachment.removing { opacity: 0; transform: scale(0.96); }

/* Phase 10: errors, loading, reasoning, citations and interaction states */
body.chat-app :where(button, a, input, textarea, select, [role="button"]) {
  transition: color var(--tc-duration-fast) var(--tc-ease-standard),
              background-color var(--tc-duration-fast) var(--tc-ease-standard),
              border-color var(--tc-duration-fast) var(--tc-ease-standard),
              opacity var(--tc-duration-fast) var(--tc-ease-standard),
              transform var(--tc-duration-fast) var(--tc-ease-standard);
}

body.chat-app :where(button, input, textarea, select):disabled {
  cursor: not-allowed;
  opacity: 0.48;
}

body.chat-app :where(.toast, .error-message, .status-card, .inline-error) {
  color: var(--tc-text);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-md);
  box-shadow: var(--tc-shadow-sm);
}

body.chat-app :where(.toast--error, .error-message, .inline-error) { border-inline-start: 3px solid var(--tc-danger); }
body.chat-app :where(.toast--success, .status-success) { border-inline-start: 3px solid var(--tc-success); }
body.chat-app :where(.toast--warning, .status-warning) { border-inline-start: 3px solid var(--tc-warning); }

body.chat-app :where(.retry-btn, [data-action="retry"]) {
  min-block-size: 2rem;
  padding-inline: var(--tc-space-3);
  color: var(--tc-text-secondary);
  background: var(--tc-surface-subtle);
  border: 0;
  border-radius: var(--tc-radius-sm);
  font-size: var(--tc-type-xs);
  font-weight: 600;
}

body.chat-app :where(.retry-btn, [data-action="retry"]):hover { color: var(--tc-text); background: var(--tc-surface-hover); }

body.chat-app :where(.thinking-block, .reasoning-block, .thinking-container, .reasoning-content) {
  margin-block: var(--tc-space-2) var(--tc-space-4);
  padding: var(--tc-space-2) var(--tc-space-3);
  color: var(--tc-text-secondary);
  background: transparent;
  border: 0;
  border-inline-start: 2px solid var(--tc-border-strong);
  border-radius: 0;
  font-size: var(--tc-type-sm);
}

body.chat-app :where(.thinking-header, .reasoning-header, .thinking-toggle, .reasoning-toggle) {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-xs);
  font-weight: 600;
}

body.chat-app :where(.citation, .citation-link, .source-chip) {
  display: inline-flex;
  max-inline-size: 100%;
  align-items: center;
  padding: 0.12rem 0.42rem;
  color: var(--tc-accent);
  background: var(--tc-accent-soft);
  border: 0;
  border-radius: var(--tc-radius-pill);
  font-size: var(--tc-type-2xs);
  line-height: 1.45;
  text-decoration: none;
  vertical-align: 0.08em;
}

body.chat-app :where(.sources-section, .citations-section) {
  margin-block-start: var(--tc-space-6);
  padding-block-start: var(--tc-space-3);
  border-block-start: 1px solid var(--tc-border);
}

body.chat-app :where(.source-url, .citation-url) {
  display: block;
  overflow: hidden;
  color: var(--tc-text-tertiary);
  text-overflow: ellipsis;
  white-space: nowrap;
}

body.chat-app :where(.skeleton, .loading-placeholder) {
  color: transparent !important;
  background: linear-gradient(90deg, var(--tc-surface-subtle), var(--tc-surface-hover), var(--tc-surface-subtle));
  background-size: 220% 100%;
  border-radius: var(--tc-radius-sm);
  animation: tc-skeleton 1.15s ease-in-out infinite;
}

@keyframes tc-skeleton { to { background-position: -120% 0; } }

body.chat-app .ai-typing-indicator {
  display: inline-flex;
  min-inline-size: 6.5rem;
  min-block-size: 1.75rem;
  align-items: center;
  gap: 0.3rem;
  color: var(--tc-text-tertiary);
  white-space: nowrap;
}

body.chat-app .ai-typing-indicator::after {
  margin-inline-start: 0.3rem;
  color: var(--tc-text-tertiary);
  content: "Thinking…";
  font-family: var(--tc-font-sans);
  font-size: var(--tc-type-xs);
  line-height: 1;
}

body.chat-app .ai-dot {
  display: block;
  inline-size: 0.34rem;
  block-size: 0.34rem;
  flex: 0 0 0.34rem;
  background: var(--tc-text-tertiary);
  border-radius: var(--tc-radius-pill);
  animation: tc-typing-dot 1.05s ease-in-out infinite;
}

body.chat-app .ai-dot:nth-child(2) { animation-delay: 140ms; }
body.chat-app .ai-dot:nth-child(3) { animation-delay: 280ms; }

@keyframes tc-typing-dot {
  0%, 60%, 100% { opacity: 0.34; transform: translateY(0); }
  30% { opacity: 1; transform: translateY(-0.16rem); }
}

/* Phase 11: responsive system — validated targets: 1440/1280/1024/768/430/390/360 */
@media (min-width: 1280px) {
  body.chat-app #chat-box { padding-inline: max(var(--tc-space-6), calc((100% - var(--tc-reading-width)) / 2)); }
}

@media (min-width: 768px) and (max-width: 1279px) {
  body.chat-app #topbar { padding-inline: var(--tc-space-4); }
  body.chat-app .message-row { margin-block-end: var(--tc-space-6); }
}

@media (max-width: 767px) {
  body.chat-app #sidebar {
    position: fixed;
    inset-block: 0;
    inset-inline-start: 0;
    z-index: 40;
    inline-size: min(88vw, 19rem);
    block-size: 100dvh;
    transform: translateX(-105%);
    box-shadow: var(--tc-shadow-md);
  }

  body.chat-app #sidebar.translate-x-0 { transform: translateX(0); }
  body.chat-app #sidebar-overlay { z-index: 35; background: var(--tc-overlay); backdrop-filter: blur(2px); }

  body.chat-app #chat-box {
    padding-block: var(--tc-space-5);
    padding-inline: var(--tc-space-3);
    scroll-padding-block-end: 8.5rem;
    scrollbar-gutter: auto;
  }

  body.chat-app .message-row { margin-block-end: var(--tc-space-6); gap: var(--tc-space-2); }
  body.chat-app .message-row .bubble-wrapper { max-inline-size: calc(100% - 2rem); }
  body.chat-app .message-row--user .bubble-wrapper { max-inline-size: 92%; }
  body.chat-app .msg-avatar { inline-size: 1.5rem; block-size: 1.5rem; flex-basis: 1.5rem; }

  body.chat-app #chat-box + div {
    padding-inline: var(--tc-space-2);
    padding-block-end: max(var(--tc-space-2), env(safe-area-inset-bottom));
  }

  body.chat-app #composer { border-radius: var(--tc-radius-lg); }
  body.chat-app :where(#search-toggle-btn, #scientific-toggle-btn, #code-interpreter-toggle-btn) { display: none; }
  body.chat-app .suggest-grid { grid-template-columns: 1fr; }
}

/* Phase 13: accessibility */
body.chat-app .tc-sr-only {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

body.chat-app :where(button, a, input, textarea, select, [tabindex]):focus-visible {
  outline: 2px solid var(--tc-accent);
  outline-offset: 2px;
  box-shadow: var(--tc-focus-ring);
}

body.chat-app :where([role="dialog"], [role="menu"]) :focus-visible { outline-offset: 1px; }
body.chat-app :where(button, [role="button"]) { -webkit-tap-highlight-color: transparent; touch-action: manipulation; }
body.chat-app :where(button, [role="button"]):active:not(:disabled) { transform: scale(0.98); }

body.chat-app ::selection { color: inherit; background: color-mix(in srgb, var(--tc-accent) 22%, transparent); }

@media (prefers-reduced-motion: reduce) {
  body.chat-app *,
  body.chat-app *::before,
  body.chat-app *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Agent Activity Stream */
body.chat-app .activity-stream {
  inline-size: 100%;
  margin-block: 0 var(--tc-space-4);
  color: var(--tc-text-secondary);
  font-size: var(--tc-type-xs);
}

body.chat-app .activity-summary {
  display: inline-flex;
  min-block-size: 2rem;
  align-items: center;
  gap: var(--tc-space-1);
  padding: 0 var(--tc-space-2);
  color: var(--tc-text-secondary);
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-sm);
  font-weight: 550;
  text-align: start;
}

body.chat-app .activity-summary:hover { color: var(--tc-text); background: var(--tc-surface-subtle); }
body.chat-app .activity-summary svg { inline-size: 0.875rem; block-size: 0.875rem; fill: none; stroke: currentColor; stroke-width: 1.8; transition: transform var(--tc-duration-fast) var(--tc-ease-standard); }
body.chat-app .activity-summary[aria-expanded="true"] svg { transform: rotate(180deg); }
body.chat-app .activity-summary[aria-expanded="false"] + .activity-list { display: none; }

body.chat-app .activity-list {
  display: grid;
  gap: 0.15rem;
  margin-block-start: var(--tc-space-1);
  padding-inline-start: var(--tc-space-2);
}

body.chat-app .activity-item {
  display: grid;
  grid-template-columns: 1rem minmax(0, 1fr);
  gap: var(--tc-space-2);
  align-items: start;
  min-block-size: 1.75rem;
  padding-block: 0.25rem;
}

body.chat-app .activity-item__icon { display: inline-grid; inline-size: 1rem; block-size: 1rem; place-items: center; margin-block-start: 0.08rem; color: var(--tc-text-tertiary); }
body.chat-app .activity-item__icon svg { inline-size: 0.9rem; block-size: 0.9rem; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
body.chat-app .activity-item[data-status="success"] .activity-item__icon { color: var(--tc-success); }
body.chat-app .activity-item[data-status="error"] .activity-item__icon { color: var(--tc-danger); }
body.chat-app .activity-item[data-status="cancelled"] { opacity: 0.62; }
body.chat-app .activity-item__copy { display: grid; min-inline-size: 0; }
body.chat-app .activity-item__label { overflow: hidden; color: var(--tc-text-secondary); text-overflow: ellipsis; white-space: nowrap; }
body.chat-app .activity-item__detail { overflow: hidden; color: var(--tc-text-tertiary); font-size: var(--tc-type-2xs); text-overflow: ellipsis; white-space: nowrap; }

body.chat-app .activity-spinner {
  inline-size: 0.75rem;
  block-size: 0.75rem;
  border: 1.5px solid var(--tc-border-strong);
  border-block-start-color: var(--tc-accent);
  border-radius: 50%;
  animation: tc-activity-spin 0.8s linear infinite;
}

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

@media (max-width: 430px) {
  body.chat-app .activity-stream { margin-block-end: var(--tc-space-3); }
  body.chat-app .activity-item__detail { max-inline-size: 76vw; }
}

@media (forced-colors: active) {
  body.chat-app :where(button, input, textarea, select, #composer, .suggest-card, .msg-user) {
    border: 1px solid CanvasText !important;
  }
  body.chat-app :where(a, button):focus-visible { outline: 2px solid Highlight; }
}

/* Phase 14: final polish, empty states, menus and quiet surfaces */
html { color-scheme: light; background: var(--tc-canvas); }
html.dark { color-scheme: dark; }

body.chat-app #empty-state {
  inline-size: 100%;
  max-inline-size: 38rem;
  margin-inline: auto;
  color: var(--tc-text-secondary);
}

body.chat-app #empty-state > .relative:first-child { margin-block-end: var(--tc-space-4); }
body.chat-app #empty-state > .relative:first-child > .absolute { display: none; }
body.chat-app #empty-state > .relative:first-child > .relative {
  padding: var(--tc-space-3);
  color: var(--tc-accent);
  background: var(--tc-accent-soft) !important;
  border: 0 !important;
  border-radius: var(--tc-radius-lg) !important;
  box-shadow: none !important;
}

body.chat-app #empty-state h2 {
  margin: 0;
  color: var(--tc-text) !important;
  font-size: clamp(1.4rem, 3vw, 1.8rem);
  font-weight: 650;
}

body.chat-app .empty-state-copy { margin-block: var(--tc-space-2) var(--tc-space-6); color: var(--tc-text-secondary); }
body.chat-app .suggest-grid { gap: var(--tc-space-2); }

body.chat-app .suggest-card {
  min-block-size: 4.5rem;
  padding: var(--tc-space-4);
  color: var(--tc-text-secondary);
  background: transparent;
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-lg);
  box-shadow: none;
}

body.chat-app .suggest-card:hover {
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
  border-color: var(--tc-border-strong);
  box-shadow: none;
  transform: translateY(-1px);
}

body.chat-app .suggest-title { color: var(--tc-text); font-weight: 600; }
body.chat-app .suggest-desc { color: var(--tc-text-tertiary); }

body.chat-app :where(.account-menu, .dropdown-menu, [role="menu"], .context-menu) {
  color: var(--tc-text);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-lg);
  box-shadow: var(--tc-shadow-sm);
}

body.chat-app :where(.account-menu, .dropdown-menu, [role="menu"], .context-menu) :where(button, a, [role="menuitem"]) {
  color: var(--tc-text-secondary);
  border-radius: var(--tc-radius-sm);
}

body.chat-app :where(.account-menu, .dropdown-menu, [role="menu"], .context-menu) :where(button, a, [role="menuitem"]):hover {
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
}

body.chat-app :where(#project-settings-modal, #user-settings-modal, #generated-files-modal, #rename-chat-modal) {
  background: var(--tc-overlay) !important;
  backdrop-filter: blur(3px);
}

body.chat-app :where(#project-settings-modal, #user-settings-modal, #generated-files-modal, #rename-chat-modal) > div {
  color: var(--tc-text);
  background: var(--tc-surface) !important;
  border: 1px solid var(--tc-border) !important;
  border-radius: var(--tc-radius-lg) !important;
  box-shadow: var(--tc-shadow-md) !important;
}

body.chat-app :where(#project-settings-modal, #user-settings-modal, #rename-chat-modal) :where(input, textarea) {
  color: var(--tc-text) !important;
  background: var(--tc-surface-subtle) !important;
  border-color: transparent !important;
  border-radius: var(--tc-radius-md) !important;
}

body.chat-app :where(#project-settings-modal, #user-settings-modal, #rename-chat-modal) :where(input, textarea):focus {
  border-color: var(--tc-accent) !important;
  box-shadow: var(--tc-focus-ring);
}

body.chat-app :where(i[data-lucide], svg.lucide) {
  stroke-width: 1.8;
  vector-effect: non-scaling-stroke;
}

body.chat-app :where(.glass, .glass-sidebar) { backdrop-filter: none; }
body.chat-app :where(.card, .panel):not([role="dialog"]) { box-shadow: none; }

@media (prefers-contrast: more) {
  :root { --tc-border: #aeb4bd; --tc-text-secondary: #424750; }
  html.dark { --tc-border: rgba(255, 255, 255, 0.28); --tc-text-secondary: #d2d6dc; }
}

@media (max-width: 430px) {
  body.chat-app #topbar { min-block-size: 3.25rem; padding-inline: var(--tc-space-2); }
  body.chat-app #chat-box { padding-inline: var(--tc-space-2); }
  body.chat-app #composer { min-block-size: 3.25rem; padding: 0.375rem; }
  body.chat-app #composer > button:not(#send-btn) { inline-size: 2.125rem; block-size: 2.125rem; flex-basis: 2.125rem; }
}

@media (max-width: 390px) {
  body.chat-app .message-row--user .bubble-wrapper { max-inline-size: 95%; }
  body.chat-app #voice-btn { display: none; }
}

@media (max-width: 360px) {
  body.chat-app #composer { gap: 0; }
  body.chat-app #user-in { padding-inline: var(--tc-space-2); }
  body.chat-app .msg-avatar-bot { display: none; }
  body.chat-app .message-row .bubble-wrapper { max-inline-size: 100%; }
}

@media (orientation: landscape) and (max-height: 500px) {
  body.chat-app #user-in { max-block-size: 28dvh; }
  body.chat-app #chat-box { padding-block: var(--tc-space-3); }
}

/* Phase 12: bidirectional layout and tables */
body.chat-app :where(.msg-rtl, [dir="rtl"]) { direction: rtl; text-align: start; }
body.chat-app :where(.msg-ltr, [dir="ltr"]) { direction: ltr; text-align: start; }

body.chat-app .msg-bubble :where(a, code, pre, table, kbd, samp, [dir="ltr"]) {
  unicode-bidi: isolate;
}

body.chat-app .prose .table-wrapper {
  max-inline-size: 100%;
  margin-block: var(--tc-space-4);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-lg);
  overflow-x: auto;
  overscroll-behavior-inline: contain;
}

body.chat-app .prose table {
  inline-size: 100%;
  min-inline-size: 32rem;
  border-collapse: collapse;
  color: var(--tc-text);
  font-size: var(--tc-type-sm);
  text-align: start;
}

body.chat-app .prose :where(th, td) {
  padding-block: 0.68rem;
  padding-inline: 0.8rem;
  border: 0;
  border-block-end: 1px solid var(--tc-border);
  text-align: start;
  vertical-align: top;
}

body.chat-app .prose th {
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
  font-weight: 600;
}

body.chat-app .prose tr:last-child td { border-block-end: 0; }
body.chat-app .prose.msg-ltr :where(th, td):not(:last-child) { border-inline-end: 1px solid var(--tc-border); }
body.chat-app .prose.msg-rtl :where(th, td):not(:last-child) { border-inline-end: 1px solid var(--tc-border); }
body.chat-app .prose :where(pre, code) { direction: ltr; text-align: left; }

html[dir="rtl"] body.chat-app {
  font-family: var(--tc-font-arabic);
  letter-spacing: 0;
}

html[dir="rtl"] body.chat-app #sidebar {
  border-inline-start: 0;
  border-inline-end: 1px solid var(--tc-border);
}

html[dir="rtl"] body.chat-app :where(.directional-icon, [data-directional="true"]) { transform: scaleX(-1); }

@media (max-width: 767px) {
  html[dir="rtl"] body.chat-app #sidebar { transform: translateX(105%); }
  html[dir="rtl"] body.chat-app #sidebar.translate-x-0 { transform: translateX(0); }
}

/* Phase 3: main application layout */
html,
body.chat-app {
  inline-size: 100%;
  block-size: 100%;
  min-block-size: 100%;
  overflow: hidden;
  background: var(--tc-canvas);
}

body.chat-app main,
body.chat-app #chat-container {
  block-size: 100dvh;
  min-block-size: 0;
  min-inline-size: 0;
}

body.chat-app #chat-container > :last-child {
  min-inline-size: 0;
  background: var(--tc-canvas);
}

body.chat-app #sidebar {
  inline-size: var(--tc-sidebar-width);
  flex: 0 0 var(--tc-sidebar-width);
  min-block-size: 0;
  background: var(--tc-sidebar);
  border-inline-end: 1px solid var(--tc-border);
  box-shadow: none;
}

body.chat-app #topbar {
  min-block-size: 3.625rem;
  padding-inline: clamp(var(--tc-space-3), 2vw, var(--tc-space-6));
  background: color-mix(in srgb, var(--tc-canvas) 94%, transparent);
  border-block-end: 1px solid var(--tc-border);
  backdrop-filter: blur(10px);
}

body.chat-app #chat-box {
  min-block-size: 0;
  padding-block: clamp(var(--tc-space-6), 4vh, var(--tc-space-12));
  padding-inline: max(var(--tc-space-4), calc((100% - var(--tc-reading-width)) / 2));
  scroll-padding-block: var(--tc-space-8) 9rem;
  scrollbar-gutter: stable;
  overflow-anchor: auto;
}

body.chat-app #chat-box + div {
  flex: 0 0 auto;
  padding: var(--tc-space-3) var(--tc-space-4) var(--tc-safe-bottom);
  border-block-start: 0 !important;
  background: linear-gradient(to top, var(--tc-canvas) 76%, transparent) !important;
}

body.chat-app #chat-box + div > div {
  inline-size: 100%;
  max-inline-size: var(--tc-composer-width);
  margin-inline: auto;
}

body.chat-app :where(#chat-box, #chat-list, #project-list) {
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: var(--tc-border-strong) transparent;
}

@media (min-width: 768px) and (max-width: 1100px) {
  :root { --tc-sidebar-width: 15rem; }
  body.chat-app #chat-box {
    padding-inline: clamp(var(--tc-space-5), 5vw, var(--tc-space-10));
  }
}

/* Phase 4: sidebar */
body.chat-app #sidebar > .p-5 { padding: var(--tc-space-4); }

body.chat-app #sidebar .brand-copy strong {
  color: var(--tc-text);
  font-size: var(--tc-type-sm);
  font-weight: 650;
}

body.chat-app #sidebar .brand-copy small {
  color: var(--tc-text-tertiary);
  font-size: var(--tc-type-2xs);
}

body.chat-app #sidebar :where(.sidebar-section, .sidebar-conversation-section) {
  margin-block-end: var(--tc-space-4);
}

body.chat-app #sidebar :where(.sidebar-section-head, .sidebar-conversation-heading) {
  min-block-size: 1.75rem;
  margin-block-end: var(--tc-space-1);
  padding-inline: var(--tc-space-2);
}

body.chat-app #sidebar :where(.sidebar-general-card, .project-item, .chat-item, .sidebar-history-actions button) {
  min-block-size: 2.5rem;
  padding: var(--tc-space-2) var(--tc-space-3);
  color: var(--tc-text-secondary) !important;
  background: transparent;
  border: 0 !important;
  border-radius: var(--tc-radius-md);
  box-shadow: none;
}

body.chat-app #sidebar :where(.sidebar-general-card, .project-item, .chat-item, .sidebar-history-actions button):hover {
  color: var(--tc-text) !important;
  background: var(--tc-surface-hover);
}

body.chat-app #sidebar :where(.sidebar-general-card, .project-item, .chat-item).active,
body.chat-app #sidebar :where(.sidebar-general-card, .project-item, .chat-item)[aria-current="true"] {
  color: var(--tc-text) !important;
  background: var(--tc-surface);
  box-shadow: var(--tc-shadow-xs);
}

body.chat-app #sidebar :where(.sidebar-item-title, .project-name, .chat-title) {
  min-inline-size: 0;
  overflow: hidden;
  color: inherit;
  font-weight: 500;
  text-overflow: ellipsis;
  white-space: nowrap;
}

body.chat-app #sidebar :where(.sidebar-item-meta, .project-description, .chat-meta) {
  overflow: hidden;
  color: var(--tc-text-tertiary);
  text-overflow: ellipsis;
  white-space: nowrap;
}

body.chat-app #sidebar :where(.sidebar-create-btn, #sidebar-close, .chat-menu-btn, .project-menu-btn) {
  display: inline-grid;
  inline-size: 2rem;
  block-size: 2rem;
  place-items: center;
  padding: 0;
  color: var(--tc-text-tertiary);
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-sm);
}

body.chat-app #sidebar :where(.sidebar-create-btn, #sidebar-close, .chat-menu-btn, .project-menu-btn):hover {
  color: var(--tc-text);
  background: var(--tc-surface-hover);
}

body.chat-app #sidebar .conversation-search {
  min-block-size: 2.375rem;
  margin: var(--tc-space-2) var(--tc-space-4) var(--tc-space-3);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-md);
  box-shadow: none;
}

body.chat-app #sidebar .conversation-search:focus-within {
  border-color: var(--tc-accent);
  box-shadow: var(--tc-focus-ring);
}

body.chat-app #sidebar .conversation-search input { color: var(--tc-text); }
body.chat-app #sidebar .conversation-search input::placeholder { color: var(--tc-text-tertiary); }

body.chat-app #sidebar :where(.sidebar-project-form, .chat-context-menu, .project-context-menu) {
  color: var(--tc-text);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-lg);
  box-shadow: var(--tc-shadow-sm);
}

body.chat-app #sidebar :where(.chat-item.is-loading, .project-item.is-loading) {
  pointer-events: none;
  background: linear-gradient(90deg, var(--tc-surface-subtle), var(--tc-surface-hover), var(--tc-surface-subtle));
  background-size: 220% 100%;
  animation: tc-sidebar-loading 1.1s ease-in-out infinite;
}

@keyframes tc-sidebar-loading { to { background-position: -120% 0; } }

/* Phase 5: messages */
body.chat-app .message-row {
  inline-size: 100%;
  max-inline-size: var(--tc-reading-width);
  margin: 0 auto var(--tc-space-8);
  gap: var(--tc-space-3);
  contain: layout style;
}

body.chat-app .message-row .bubble-wrapper {
  min-inline-size: 0;
  max-inline-size: calc(100% - 2.5rem);
}

body.chat-app .message-row--user .bubble-wrapper {
  max-inline-size: min(88%, 39rem);
  align-items: flex-end;
}

body.chat-app .msg-avatar {
  inline-size: 1.75rem;
  block-size: 1.75rem;
  flex: 0 0 1.75rem;
  background: transparent;
  border: 0;
  box-shadow: none;
}

body.chat-app .msg-avatar-user { display: none; }
body.chat-app .msg-avatar-bot img { inline-size: 1.625rem; block-size: 1.625rem; }

body.chat-app .msg-bubble {
  min-inline-size: 0;
  padding: 0;
  color: var(--tc-text);
  background: transparent;
  border: 0;
  box-shadow: none;
  overflow-wrap: anywhere;
}

body.chat-app .msg-user {
  padding: 0.625rem 0.875rem;
  background: var(--tc-surface-subtle);
  border: 0;
  border-radius: var(--tc-radius-lg);
  box-shadow: none;
}

body.chat-app .msg-bot {
  padding-block: 0.125rem;
  background: transparent;
  border: 0;
  border-radius: 0;
}

body.chat-app .msg-actions {
  min-block-size: 2rem;
  margin-block-start: var(--tc-space-2);
  opacity: 0;
}

body.chat-app .message-row:hover .msg-actions,
body.chat-app .message-row:focus-within .msg-actions { opacity: 1; }

body.chat-app .msg-copy-btn {
  inline-size: 2rem;
  block-size: 2rem;
  color: var(--tc-text-tertiary);
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-sm);
}

body.chat-app .msg-copy-btn:hover {
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
}

body.chat-app .message-row:has([data-live-message="true"]) {
  min-block-size: 2.25rem;
  overflow-anchor: auto;
}

@media (hover: none) { body.chat-app .msg-actions { opacity: 1; } }

/* Phase 6: composer */
body.chat-app #composer {
  min-block-size: 3.5rem;
  padding: var(--tc-space-2);
  gap: var(--tc-space-1);
  align-items: flex-end;
  color: var(--tc-text);
  background: var(--tc-surface);
  border: 1px solid var(--tc-border-strong);
  border-radius: var(--tc-radius-xl);
  box-shadow: var(--tc-shadow-sm);
}

body.chat-app #composer:focus-within {
  border-color: color-mix(in srgb, var(--tc-accent) 62%, var(--tc-border));
  box-shadow: var(--tc-shadow-sm), var(--tc-focus-ring);
}

body.chat-app #user-in {
  min-block-size: 2.35rem;
  max-block-size: min(40dvh, 13rem);
  padding: 0.52rem 0.625rem;
  color: var(--tc-text) !important;
  line-height: var(--tc-leading-normal);
  scrollbar-width: thin;
}

body.chat-app #user-in::placeholder { color: var(--tc-text-tertiary); }

body.chat-app #composer > button:not(#send-btn) {
  display: inline-grid;
  inline-size: 2.25rem;
  block-size: 2.25rem;
  flex: 0 0 2.25rem;
  place-items: center;
  padding: 0;
  color: var(--tc-text-tertiary) !important;
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-md);
  opacity: 1 !important;
}

body.chat-app #composer > button:not(#send-btn):hover {
  color: var(--tc-text) !important;
  background: var(--tc-surface-subtle);
}

body.chat-app #composer > button[aria-pressed="true"] {
  color: var(--tc-accent) !important;
  background: var(--tc-accent-soft);
}

body.chat-app #send-btn {
  inline-size: 2.375rem;
  block-size: 2.375rem;
  flex: 0 0 2.375rem;
  color: var(--tc-on-accent);
  background: var(--tc-accent);
  border: 0;
  border-radius: var(--tc-radius-md);
  box-shadow: none;
}

body.chat-app #send-btn:hover:not(:disabled) {
  background: var(--tc-accent-hover);
  transform: translateY(-1px);
}

body.chat-app #send-btn:active:not(:disabled) { transform: translateY(0) scale(0.97); }
body.chat-app #send-btn:disabled { color: var(--tc-text-tertiary); background: var(--tc-surface-hover); }

body.chat-app #send-btn.stop-btn {
  color: var(--tc-canvas);
  background: var(--tc-text);
}

body.chat-app #composer[aria-busy="true"] { border-color: var(--tc-border-strong); }
body.chat-app #composer.is-error { border-color: var(--tc-danger); }
body.chat-app #composer.is-uploading::after {
  position: absolute;
  inset-inline: var(--tc-radius-lg);
  inset-block-end: 0;
  block-size: 2px;
  background: var(--tc-accent);
  border-radius: var(--tc-radius-pill);
  content: "";
  transform-origin: inline-start;
  animation: tc-upload-progress 1s var(--tc-ease-standard) infinite;
}

@keyframes tc-upload-progress {
  0% { transform: scaleX(0.12); opacity: 0.5; }
  60% { transform: scaleX(0.72); opacity: 1; }
  100% { transform: scaleX(1); opacity: 0; }
}

body.chat-app.drag-over #composer,
body.chat-app #composer.drag-over {
  border-color: var(--tc-accent);
  background: var(--tc-accent-soft);
}

/* Phase 7: markdown */
body.chat-app .prose > :first-child { margin-block-start: 0; }
body.chat-app .prose > :last-child { margin-block-end: 0; }

body.chat-app .prose :where(h1, h2, h3, h4) {
  margin-block: 1.5em 0.55em;
  color: var(--tc-text);
  font-weight: 650;
  line-height: 1.3;
  letter-spacing: -0.018em;
}

body.chat-app .prose h1 { font-size: 1.5rem; }
body.chat-app .prose h2 { font-size: 1.25rem; }
body.chat-app .prose h3 { font-size: 1.075rem; }
body.chat-app .prose h4 { font-size: 1rem; }
body.chat-app .prose p { margin-block: 0.72em; }

body.chat-app .prose :where(ul, ol) {
  margin-block: 0.75em;
  padding-inline-start: 1.5em;
}

body.chat-app .prose :where(ul, ol) :where(ul, ol) { margin-block: 0.35em; }
body.chat-app .prose li { margin-block: 0.3em; padding-inline-start: 0.2em; }
body.chat-app .prose li::marker { color: var(--tc-text-tertiary); }

body.chat-app .prose blockquote {
  margin: 1em 0;
  padding: 0.2em var(--tc-space-4);
  color: var(--tc-text-secondary);
  background: transparent;
  border: 0;
  border-inline-start: 3px solid var(--tc-border-strong);
}

body.chat-app .prose a {
  color: var(--tc-accent);
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--tc-accent) 38%, transparent);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

body.chat-app .prose a:hover { text-decoration-color: currentColor; }

body.chat-app .prose hr {
  margin-block: var(--tc-space-6);
  border: 0;
  border-block-start: 1px solid var(--tc-border);
}

body.chat-app .prose :where(del, s) { color: var(--tc-text-tertiary); }
body.chat-app .prose mark { color: inherit; background: var(--tc-warning-soft); border-radius: 0.2em; }

body.chat-app .prose :not(pre) > code {
  padding: 0.14em 0.38em;
  color: var(--tc-text);
  background: var(--tc-surface-subtle);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-xs);
  font-size: 0.88em;
  direction: ltr;
  unicode-bidi: isolate;
}

/* Phase 8: code blocks */
body.chat-app :where(.code-block-wrapper, .prose pre) {
  position: relative;
  max-inline-size: 100%;
  margin-block: var(--tc-space-4);
  color: var(--tc-code-text);
  background: var(--tc-code-surface);
  border: 1px solid var(--tc-border);
  border-radius: var(--tc-radius-lg);
  box-shadow: none;
  direction: ltr;
  text-align: left;
  overflow: auto;
  overscroll-behavior-inline: contain;
}

body.chat-app .code-header {
  position: sticky;
  inset-block-start: 0;
  z-index: 1;
  min-block-size: 2.375rem;
  padding-inline: var(--tc-space-3) var(--tc-space-2);
  color: #aeb5c1;
  background: color-mix(in srgb, var(--tc-code-surface) 88%, white);
  border-block-end: 1px solid rgba(255, 255, 255, 0.08);
  font-family: var(--tc-font-sans);
  font-size: var(--tc-type-xs);
}

body.chat-app :where(.code-language, .language-label) {
  overflow: hidden;
  color: #aeb5c1;
  font-size: var(--tc-type-2xs);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-overflow: ellipsis;
  text-transform: uppercase;
  white-space: nowrap;
}

body.chat-app .prose pre code {
  display: block;
  min-inline-size: max-content;
  padding: var(--tc-space-4);
  color: var(--tc-code-text);
  background: transparent;
  border: 0;
  font-family: var(--tc-font-mono);
  font-size: 0.8125rem;
  line-height: 1.65;
  tab-size: 2;
  white-space: pre;
}

body.chat-app :where(.copy-code-btn, .code-copy-btn) {
  min-block-size: 1.875rem;
  padding-inline: var(--tc-space-2);
  color: #c8ced8;
  background: transparent;
  border: 0;
  border-radius: var(--tc-radius-xs);
}

body.chat-app :where(.copy-code-btn, .code-copy-btn):hover { color: #fff; background: rgba(255, 255, 255, 0.09); }
body.chat-app :where(.copy-code-btn, .code-copy-btn).is-copied { color: #77d9ab; }
body.chat-app :where(.copy-code-btn, .code-copy-btn).is-copy-error { color: #ff9696; }

@media (max-width: 430px) {
  body.chat-app :where(.code-block-wrapper, .prose pre) {
    margin-inline: calc(var(--tc-space-1) * -1);
    border-radius: var(--tc-radius-md);
  }
  body.chat-app .prose pre code { font-size: 0.78rem; }
}

/* Final cascade guards: responsive and accessibility rules remain authoritative. */
@media (max-width: 767px) {
  body.chat-app #sidebar { inline-size: min(88vw, 19rem); transform: translateX(-105%); }
  body.chat-app #sidebar.translate-x-0 { transform: translateX(0); }
  html[dir="rtl"] body.chat-app #sidebar { transform: translateX(105%); }
  html[dir="rtl"] body.chat-app #sidebar.translate-x-0 { transform: translateX(0); }
  body.chat-app #chat-box { padding-block: var(--tc-space-5); padding-inline: var(--tc-space-3); scroll-padding-block-end: 8.5rem; }
  body.chat-app #chat-box + div { padding-inline: var(--tc-space-2); padding-block-end: max(var(--tc-space-2), env(safe-area-inset-bottom)); }
  body.chat-app #composer { border-radius: var(--tc-radius-lg); }
}

@media (max-width: 430px) {
  body.chat-app #topbar { min-block-size: 3.25rem; padding-inline: var(--tc-space-2); }
  body.chat-app #chat-box { padding-inline: var(--tc-space-2); }
  body.chat-app #composer { min-block-size: 3.25rem; padding: 0.375rem; }
}

@media (prefers-reduced-motion: reduce) {
  body.chat-app *, body.chat-app *::before, body.chat-app *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}