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

:root {
  --bg: #0f1117;
  --bg-surface: #1a1d27;
  --bg-hover: #22263a;
  --border: #2a2d3e;
  --accent: #6c63ff;
  --accent-hover: #5a52e0;
  --text: #e0e2f0;
  --text-muted: #7b7f9e;
  --text-dim: #4a4e6b;
  --user-bubble: #1e2438;
  --assistant-bubble: #1a1d27;
  --success: #4ade80;
  --error: #f87171;
  --warning: #fbbf24;
  --radius: 12px;
  --sidebar-width: 280px;
  --mode-study: #3a7d52;
  --mode-support: #8a6d1e;
  --mode-interview: #7d3030;
}

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.6;
}

/* Layout */
.layout {
  display: flex;
  height: 100vh;
  overflow: hidden;
}

/* Sidebar — collapsible on all screen sizes */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  transition: width 0.25s ease;
  overflow: hidden;
  /* Collapsed by default on all screens; initApp adds .open on desktop */
}

/* Desktop: sidebar collapses in-place (no absolute positioning) */
@media (min-width: 641px) {
  .sidebar {
    position: relative;
    width: 0;
    border-right-width: 0;
  }

  .sidebar.open {
    width: var(--sidebar-width);
    border-right-width: 1px;
  }
}

.sidebar-header {
  padding: 16px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 16px;
  color: var(--text);
}

.logo-icon {
  font-size: 20px;
}


.sidebar-modules {
  flex: 1;
  overflow-y: auto;
  overscroll-behavior: contain;
  padding: 8px;
}

.loading-sidebar {
  color: var(--text-muted);
  font-size: 13px;
  padding: 16px;
  text-align: center;
}

/* Course-level toggle (top of sidebar hierarchy) */
.course-group {
  margin-bottom: 2px;
}

.course-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 10px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 11px;
  font-weight: 700;
  color: var(--text-dim);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  user-select: none;
  transition: background 0.1s, color 0.1s;
}

.course-header:hover {
  background: var(--bg-hover);
  color: var(--text-muted);
}

.course-name {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.course-arrow {
  font-size: 9px;
  transition: transform 0.2s;
  flex-shrink: 0;
}

.course-group.open .course-arrow {
  transform: rotate(90deg);
}

.course-body {
  display: none;
  padding-left: 8px;
  margin-bottom: 4px;
}

.course-group.open .course-body {
  display: block;
}

.module-group {
  margin-bottom: 4px;
}

.module-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.03em;
  text-transform: uppercase;
  user-select: none;
  transition: background 0.1s;
}

.module-header:hover {
  background: var(--bg-hover);
  color: var(--text);
}

.module-lesson-count {
  font-size: 11px;
  font-weight: 500;
  background: var(--bg-hover);
  color: var(--text-dim);
  border-radius: 10px;
  padding: 1px 7px;
  letter-spacing: 0;
  text-transform: none;
}

.module-arrow {
  margin-left: auto;
  transition: transform 0.2s;
  font-size: 10px;
}

.module-group.open .module-arrow {
  transform: rotate(90deg);
}

.lesson-list {
  display: none;
  padding-left: 10px;
  margin-bottom: 4px;
}

.module-group.open .lesson-list {
  display: block;
}

.lesson-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 13px;
  color: var(--text-muted);
  transition: background 0.1s, color 0.1s;
  min-width: 0;
}

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

.lesson-item.active {
  background: var(--accent);
  color: #fff;
}
.lesson-item.active .lesson-type-icon,
.lesson-item.active .lesson-name {
  opacity: 1;
  color: #fff;
}

.lesson-type-icon {
  font-size: 11px;
  opacity: 0.7;
  flex-shrink: 0;
}

.lesson-name {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
  min-width: 0;
}

.lesson-check {
  border: 1px solid var(--text-dim);
  border-radius: 50%;
  color: var(--text-dim);
  font-size: 10px;
  width: 16px;
  height: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  line-height: 1;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}

.lesson-check.done {
  background: var(--success);
  border-color: var(--success);
  color: #000;
  font-weight: 700;
}

.lesson-item.completed .lesson-name {
  opacity: 0.45;
  text-decoration: line-through;
}

/* Chat area */
.chat-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

.chat-header {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
}

.sidebar-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: 6px;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-family: inherit;
  flex-shrink: 0;
  transition: color 0.1s, border-color 0.1s, background 0.1s;
  white-space: nowrap;
}

.sidebar-toggle:hover {
  color: var(--text);
  border-color: var(--accent);
}

.sidebar-toggle-label {
  font-size: 13px;
  font-weight: 500;
}

.chat-header-info {
  display: flex;
  align-items: center;
  gap: 10px;
}

.chat-header-info h1 {
  font-size: 17px;
  font-weight: 700;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-dim);
  flex-shrink: 0;
}

.status-dot.online {
  background: var(--success);
  box-shadow: 0 0 6px rgba(74, 222, 128, 0.5);
}

.status-dot.error {
  background: var(--error);
}

.status-text {
  font-size: 13px;
  color: var(--text-muted);
}

/* Tab bar */
.tab-bar {
  display: flex;
  align-items: center;
  gap: 0;
  border-bottom: 1px solid var(--border);
  background: var(--bg-surface);
  flex-shrink: 0;
  min-height: 38px;
  padding: 0 8px;
  overflow: hidden;
}

.tab-list {
  display: flex;
  align-items: stretch;
  gap: 2px;
  overflow-x: auto;
  scroll-behavior: smooth;
  flex: 1;
  padding: 4px 0;
  /* Hide scrollbar but allow scrolling */
  scrollbar-width: none;
}

.tab-list::-webkit-scrollbar {
  display: none;
}

.tab-item {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  color: var(--text-muted);
  background: none;
  border: 1px solid transparent;
  white-space: nowrap;
  flex-shrink: 0;
  max-width: 180px;
  transition: background 0.1s, color 0.1s, border-color 0.1s, margin 0.12s ease;
  user-select: none;
}

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

.tab-item.active {
  background: var(--bg);
  color: var(--text);
  border-color: var(--border);
}

.tab-label {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
  min-width: 0;
}

.tab-close {
  background: none;
  border: none;
  color: var(--text-dim);
  font-size: 14px;
  cursor: pointer;
  padding: 0 2px;
  line-height: 1;
  border-radius: 3px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  transition: color 0.1s, background 0.1s;
}

.tab-close:hover {
  color: var(--error);
  background: rgba(248, 113, 113, 0.15);
}

.tab-add-btn {
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 3px 10px;
  cursor: pointer;
  flex-shrink: 0;
  margin-left: 6px;
  white-space: nowrap;
  transition: color 0.1s, border-color 0.1s, background 0.1s;
}

.tab-add-btn:hover {
  color: var(--text);
  border-color: var(--accent);
}

/* Pane-visibility dot — which pane is displaying this tab (split mode) */
.tab-pane-dot {
  font-size: 6px;
  line-height: 1;
  flex-shrink: 0;
  opacity: 0.8;
}
.tab-pane-dot.left  { color: var(--accent); }
.tab-pane-dot.right { color: #f0a060; }

/* Context mark — EMA will respond in this tab's lesson */
.tab-ctx-mark {
  font-size: 11px;
  color: var(--accent);
  opacity: 0.7;
  flex-shrink: 0;
  margin-left: -2px;
}
.tab-item.tab-context {
  border-color: color-mix(in srgb, var(--accent) 35%, transparent);
}

/* Drag-and-drop tab reordering */
.tab-item.dragging {
  opacity: 0.35;
  cursor: grabbing;
}

.tab-item.drop-before {
  border-left: 2px solid var(--accent);
}

.tab-item.drop-after {
  border-right: 2px solid var(--accent);
}

/* Messages */
.messages {
  flex: 1;
  overflow-y: auto;
  overscroll-behavior: contain;
  scroll-behavior: smooth;
  padding: 24px 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.welcome {
  text-align: center;
  max-width: 520px;
  margin: auto;
  padding: 32px 16px;
}

.welcome-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.welcome h2 {
  font-size: 24px;
  margin-bottom: 10px;
}

.welcome p {
  color: var(--text-muted);
  margin-bottom: 24px;
  line-height: 1.7;
}

.welcome-suggestions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: center;
}

.suggestion {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text);
  font-size: 13px;
  padding: 8px 16px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
}

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

/* Message bubbles */
.message {
  display: flex;
  gap: 12px;
  max-width: 820px;
  width: 100%;
  align-self: flex-start;
}

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

.avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 14px;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 2px;
}

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

.message.assistant .avatar {
  background: transparent;
  padding: 0;
  overflow: hidden;
}

.avatar-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  display: block;
}

.bubble {
  background: var(--assistant-bubble);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  max-width: calc(100% - 44px);
  word-break: break-word;
}

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

/* Mode-colored left border on messages */
.message.mode-study .bubble {
  border-left: 3px solid var(--mode-study);
  background: color-mix(in srgb, var(--mode-study) 8%, var(--assistant-bubble));
}
.message.user.mode-study .bubble {
  background: color-mix(in srgb, var(--mode-study) 8%, var(--user-bubble));
}

.message.mode-support .bubble {
  border-left: 3px solid var(--mode-support);
  background: color-mix(in srgb, var(--mode-support) 8%, var(--assistant-bubble));
}
.message.user.mode-support .bubble {
  background: color-mix(in srgb, var(--mode-support) 8%, var(--user-bubble));
}

.message.mode-interview .bubble {
  border-left: 3px solid var(--mode-interview);
  background: color-mix(in srgb, var(--mode-interview) 8%, var(--assistant-bubble));
}
.message.user.mode-interview .bubble {
  background: color-mix(in srgb, var(--mode-interview) 8%, var(--user-bubble));
}

/* Streaming cursor on the active response */
.bubble.streaming::after {
  content: "▊";
  color: var(--accent);
  animation: blink-cursor 1s step-end infinite;
  font-size: 0.85em;
  margin-left: 2px;
}

@keyframes blink-cursor {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

/* Error state bubble */
.bubble.error-bubble {
  color: var(--error);
  border-color: rgba(248, 113, 113, 0.3);
  background: rgba(248, 113, 113, 0.05);
}

/* Markdown content inside bubbles */
.bubble p { margin-bottom: 10px; }
.bubble p:last-child { margin-bottom: 0; }
.bubble h1, .bubble h2, .bubble h3 { margin: 12px 0 6px; }
.bubble ul, .bubble ol { padding-left: 20px; margin-bottom: 10px; }
.bubble li { margin-bottom: 4px; }
.bubble code {
  background: rgba(108, 99, 255, 0.15);
  border: 1px solid rgba(108, 99, 255, 0.2);
  border-radius: 4px;
  padding: 1px 5px;
  font-family: "JetBrains Mono", "Fira Code", monospace;
  font-size: 13px;
  color: #a5b4fc;
}
.bubble pre {
  background: #0d0f1a;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  overflow-x: auto;
  margin: 10px 0;
  position: relative;
}

.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 11px;
  font-family: inherit;
  padding: 3px 8px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.copy-btn:hover {
  color: var(--text);
  border-color: var(--accent);
}

.copy-btn.copied {
  color: var(--success);
  border-color: var(--success);
}
.bubble pre code {
  background: none;
  border: none;
  padding: 0;
  color: #c9d1ff;
}
.bubble a { color: var(--accent); text-decoration: none; }
.bubble a:hover { text-decoration: underline; }
.bubble blockquote {
  border-left: 3px solid var(--accent);
  padding-left: 12px;
  color: var(--text-muted);
  margin: 8px 0;
}

/* Typing indicator */
.typing-indicator {
  display: flex;
  gap: 4px;
  align-items: center;
  height: 20px;
  padding: 4px 0;
}

.typing-dot {
  width: 7px;
  height: 7px;
  background: var(--text-muted);
  border-radius: 50%;
  animation: bounce 1.2s infinite;
}

.typing-dot:nth-child(2) { animation-delay: 0.2s; }
.typing-dot:nth-child(3) { animation-delay: 0.4s; }

@keyframes bounce {
  0%, 60%, 100% { transform: translateY(0); opacity: 0.5; }
  30% { transform: translateY(-5px); opacity: 1; }
}

/* Input area */
.input-area {
  padding: 16px 20px 20px;
  border-top: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
}

.input-wrapper {
  display: flex;
  align-items: flex-end;
  gap: 10px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 10px 12px;
  transition: border-color 0.2s;
}

.input-wrapper:focus-within {
  border-color: var(--accent);
}

textarea {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--text);
  font-size: 15px;
  font-family: inherit;
  resize: none;
  max-height: 160px;
  line-height: 1.6;
}

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

.btn-send {
  background: var(--accent);
  border: none;
  border-radius: 8px;
  color: #fff;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
  transition: background 0.15s, opacity 0.15s;
}

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

.btn-send:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.input-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 8px;
}

.btn-stuck {
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 4px 12px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.btn-stuck:hover:not(:disabled) {
  color: var(--text);
  border-color: var(--accent);
}

.btn-stuck:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* Mode guide modal */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 20px;
}

.modal-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 32px;
  max-width: 780px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.modal-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text);
}

.modal-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 18px;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  transition: color 0.15s, background 0.15s;
}

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

.modal-subtitle {
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 24px;
  line-height: 1.5;
}

.modal-modes {
  display: flex;
  gap: 16px;
  margin-bottom: 24px;
}

.modal-mode-card {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.modal-mode-name {
  font-size: 15px;
  font-weight: 700;
}

.mode-study-text  { color: var(--mode-study); }
.mode-support-text { color: var(--mode-support); }
.mode-interview-text { color: var(--mode-interview); }

.modal-mode-desc {
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.6;
  flex: 1;
}

.modal-best-for {
  font-size: 12px;
  color: var(--text-dim);
  border-top: 1px solid var(--border);
  padding-top: 10px;
  line-height: 1.5;
}

.best-for-label {
  font-weight: 600;
  color: var(--text-muted);
  margin-right: 4px;
}

.btn-got-it {
  display: block;
  margin: 0 auto;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 9px 32px;
  font-size: 14px;
  font-family: inherit;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s;
}

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

@media (max-width: 600px) {
  .modal-modes {
    flex-direction: column;
  }
  .modal-card {
    padding: 20px 16px;
  }
}

/* Modal course/lesson list */
.modal-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 24px 0 20px;
}

.modal-modules-section {
  margin-bottom: 24px;
}

.modal-modules-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  margin: 0 0 6px;
}

.modal-modules-subtitle {
  font-size: 12px;
  color: var(--text-muted);
  margin: 0 0 14px;
  line-height: 1.5;
}

.modal-module-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.modal-module-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  padding: 8px 12px;
  border-radius: 6px;
  background: var(--bg);
  border: 1px solid var(--border);
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  user-select: none;
  transition: background 0.15s;
}

.modal-module-header:hover {
  background: var(--bg-hover);
}

.modal-module-arrow {
  font-size: 10px;
  color: var(--text-muted);
  transition: transform 0.15s;
  flex-shrink: 0;
}

.modal-module-group.open .modal-module-arrow {
  transform: rotate(90deg);
}

.modal-lesson-list {
  display: none;
  flex-direction: column;
  padding: 4px 0 4px 10px;
}

.modal-module-group.open .modal-lesson-list {
  display: flex;
}

.modal-lesson-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 5px 8px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--text-muted);
  transition: background 0.1s, color 0.1s;
}

.modal-lesson-item:hover {
  background: var(--bg-hover);
  color: var(--text);
}

.modal-lesson-icon {
  font-size: 13px;
  flex-shrink: 0;
}

.modal-lesson-name {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.btn-explain-lesson {
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 11px;
  font-family: inherit;
  padding: 2px 8px;
  cursor: pointer;
  flex-shrink: 0;
  opacity: 0;
  transition: color 0.15s, border-color 0.15s, background 0.15s, opacity 0.15s;
}

.modal-lesson-item:hover .btn-explain-lesson {
  opacity: 1;
}

.btn-explain-lesson:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* Feedback button in header */
.btn-feedback {
  background: none;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 5px 12px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
  margin-right: 8px;
}
.btn-feedback:hover {
  color: var(--text);
  border-color: var(--accent);
}

/* Feedback modal */
.feedback-modal-card {
  max-width: 480px;
}
.feedback-type-row {
  display: flex;
  gap: 10px;
  margin-bottom: 14px;
}
.feedback-type-btn {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 13px;
  font-family: inherit;
  padding: 8px 0;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}
.feedback-type-btn.active {
  border-color: var(--accent);
  color: var(--text);
  background: var(--bg-hover);
}
.feedback-type-btn:hover:not(.active) {
  border-color: var(--text-dim);
  color: var(--text);
}
.feedback-textarea {
  width: 100%;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  line-height: 1.5;
  padding: 10px 12px;
  resize: vertical;
  box-sizing: border-box;
  transition: border-color 0.15s;
}
.feedback-textarea:focus {
  outline: none;
  border-color: var(--accent);
}
.feedback-char-counter {
  font-size: 11px;
  color: var(--text-dim);
  text-align: right;
  margin: 4px 0 12px;
}
.feedback-error {
  color: #e06c75;
  font-size: 13px;
  margin-bottom: 10px;
}
.feedback-success {
  color: #98c379;
  font-size: 13px;
  text-align: center;
  margin-bottom: 10px;
}

/* Screenshot upload row */
.feedback-screenshot-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 12px;
}
.btn-screenshot {
  background: none;
  border: 1px dashed var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 5px 10px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
  white-space: nowrap;
}
.btn-screenshot:hover {
  color: var(--text);
  border-color: var(--accent);
}
.feedback-screenshot-name {
  font-size: 12px;
  color: var(--text-muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  max-width: 180px;
}
.feedback-screenshot-clear {
  background: none;
  border: none;
  color: var(--text-dim);
  font-size: 12px;
  cursor: pointer;
  padding: 0;
  line-height: 1;
  flex-shrink: 0;
}
.feedback-screenshot-clear:hover {
  color: #e06c75;
}

/* Background knowledge chips (onboarding) */
.bg-chips-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
  padding: 4px 0;
}

.bg-chip {
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 13px;
  font-family: inherit;
  padding: 5px 14px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.bg-chip:hover {
  color: var(--text);
  border-color: var(--accent);
}

.bg-chip.active {
  color: var(--accent);
  border-color: var(--accent);
  background: rgba(108, 99, 255, 0.15);
}

/* ? button next to mode pills */
.btn-mode-guide {
  background: none;
  border: 1px solid var(--border);
  border-radius: 50%;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  flex-shrink: 0;
  transition: color 0.15s, border-color 0.15s;
}

.btn-mode-guide:hover {
  color: var(--text);
  border-color: var(--accent);
}

/* Mode pill hover tooltip */
.mode-tooltip {
  position: fixed;
  z-index: 999;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 9px 12px;
  max-width: 240px;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.12s;
  box-shadow: 0 4px 16px rgba(0,0,0,0.4);
}

.mode-tooltip.visible {
  opacity: 1;
}

.mode-tooltip-title {
  font-size: 12px;
  color: var(--text);
  font-weight: 500;
  line-height: 1.5;
  margin-bottom: 4px;
}

.mode-tooltip-desc {
  font-size: 11px;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Topic chips */
.topic-chips-prompt {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.topic-chip-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.topic-chip {
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 13px;
  font-family: inherit;
  padding: 5px 14px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.topic-chip:hover:not(.frozen) {
  border-color: var(--accent);
  color: var(--text);
}

.topic-chip.active {
  border-color: var(--accent);
  color: var(--text);
  background: rgba(108, 99, 255, 0.15);
}

.topic-chip.frozen {
  opacity: 0.45;
  cursor: default;
}

/* Mode selector pills */
.mode-selector {
  display: flex;
  gap: 6px;
  align-items: center;
}

.mode-pill {
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 4px 12px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
}

.mode-pill[data-mode="study"].active {
  border-color: var(--mode-study);
  color: var(--text);
  background: color-mix(in srgb, var(--mode-study) 15%, transparent);
}

.mode-pill[data-mode="support"].active {
  border-color: var(--mode-support);
  color: var(--text);
  background: color-mix(in srgb, var(--mode-support) 15%, transparent);
}

.mode-pill[data-mode="interview"].active {
  border-color: var(--mode-interview);
  color: var(--text);
  background: color-mix(in srgb, var(--mode-interview) 15%, transparent);
}

.mode-pill[data-mode="study"]:hover:not(.active) {
  color: var(--text);
  border-color: var(--mode-study);
}

.mode-pill[data-mode="support"]:hover:not(.active) {
  color: var(--text);
  border-color: var(--mode-support);
}

.mode-pill[data-mode="interview"]:hover:not(.active) {
  color: var(--text);
  border-color: var(--mode-interview);
}

/* Character counter */
.char-counter {
  font-size: 11px;
  color: transparent;
  transition: color 0.2s;
}

.char-counter.warn {
  color: var(--warning);
}

.char-counter.danger {
  color: var(--error);
}

.quiz-chip-group {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 10px;
}

.quiz-chip {
  display: inline-block;
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 12px;
  font-family: inherit;
  padding: 4px 14px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.quiz-chip:hover {
  color: var(--accent);
  border-color: var(--accent);
}

/* Answer chips — numbered options from EMA responses */
.answer-chip-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.answer-chip {
  background: none;
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 13px;
  font-family: inherit;
  padding: 5px 14px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  text-align: left;
}

.answer-chip:hover:not(.frozen) {
  border-color: var(--accent);
  color: var(--text);
}

.answer-chip.active {
  border-color: var(--accent);
  color: var(--text);
  background: rgba(108, 99, 255, 0.15);
}

.answer-chip.frozen {
  opacity: 0.45;
  cursor: default;
}

.input-hint {
  font-size: 11px;
  color: var(--text-dim);
  margin-top: 8px;
  text-align: center;
}

/* Entry chips (first-time and returning welcome) */
.entry-chips-wrapper {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  margin: auto;
  padding: 40px 16px;
  max-width: 480px;
  width: 100%;
}

.entry-chips-prompt {
  color: var(--text-muted);
  font-size: 15px;
  text-align: center;
}

.entry-chip-group {
  display: flex;
  flex-direction: column;
  gap: 10px;
  width: 100%;
}

.entry-chip {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
  padding: 12px 20px;
  cursor: pointer;
  text-align: left;
  transition: background 0.15s, border-color 0.15s;
}

.entry-chip:hover {
  background: var(--bg-hover);
  border-color: var(--accent);
}

/* Lesson welcome — title line above chips */
.lesson-welcome-title {
  color: var(--text);
  font-size: 16px;
  font-weight: 600;
  text-align: center;
}

/* Hint line below chips */
.entry-chips-hint {
  color: var(--text-muted);
  font-size: 13px;
  text-align: center;
  margin-top: 4px;
}

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

/* Login page */
.login-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg);
}

.login-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 36px;
  width: 100%;
  max-width: 380px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
}

.login-logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 18px;
  margin-bottom: 24px;
  color: var(--text);
}

.login-title {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 24px;
  color: var(--text);
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.login-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.login-field label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
}

.login-field input {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 15px;
  font-family: inherit;
  padding: 10px 14px;
  outline: none;
  transition: border-color 0.2s;
}

.login-field input:focus {
  border-color: var(--accent);
}

.login-error {
  font-size: 13px;
  color: var(--error);
  min-height: 18px;
}

.btn-login {
  background: var(--accent);
  border: none;
  border-radius: 8px;
  color: #fff;
  font-size: 15px;
  font-family: inherit;
  font-weight: 600;
  padding: 11px;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  margin-top: 4px;
}

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

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

/* Google Sign-In divider + button */
.login-divider {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 20px 0 16px;
  color: var(--text-muted);
  font-size: 13px;
}
.login-divider::before,
.login-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}
.g_id_signin {
  display: flex;
  justify-content: center;
}

/* Header user / logout */
.header-user {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 10px;
}

.header-username {
  font-size: 13px;
  color: var(--text-muted);
}

.btn-logout {
  display: flex;
  align-items: center;
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-muted);
  font-size: 13px;
  font-family: inherit;
  padding: 6px 12px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  white-space: nowrap;
}

.btn-logout:hover {
  color: #e57373;
  border-color: #e57373;
  background: rgba(229, 115, 115, 0.08);
}

/* Responsive — mobile sidebar overlays content */
@media (max-width: 640px) {
  .sidebar {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    z-index: 100;
    width: var(--sidebar-width) !important;
    transform: translateX(-100%);
    border-right-width: 1px !important;
  }

  .sidebar.open {
    transform: translateX(0);
    width: var(--sidebar-width) !important;
  }

  .sidebar-toggle-label {
    display: none;
  }
}

/* ── Two-pane layout ─────────────────────────────────────────────────────── */

.pane-container {
  display: flex;
  flex: 1;
  overflow: hidden;
  min-height: 0;
}

.pane {
  display: flex;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
  min-width: 0;
}

.pane-content {
  flex: 1;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  min-height: 0;
}

/* Split mode */
.pane-container.split #paneLeft  { flex: 1 1 50%; }
.pane-container.split #paneRight { flex: 1 1 50%; border-left: 1px solid var(--border); }
#paneRight { display: none; }
.pane-container.split #paneRight { display: flex; }

/* Resizable divider */
.pane-divider {
  width: 4px;
  background: var(--border);
  cursor: col-resize;
  flex-shrink: 0;
  display: none;
  transition: background 0.15s;
}
.pane-container.split .pane-divider { display: block; }
.pane-divider:hover, .pane-divider.dragging { background: var(--accent); }

/* Per-pane tab bar */
.pane-tab-bar {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
  transition: background 0.1s, border-color 0.1s;
}
.pane-tab-bar.drag-over {
  background: color-mix(in srgb, var(--accent) 12%, var(--bg));
  border-bottom-color: var(--accent);
  outline: 2px dashed var(--accent);
  outline-offset: -2px;
}

/* Split toggle button */
.pane-split-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 13px;
  transition: color 0.1s, border-color 0.1s;
  flex-shrink: 0;
}
.pane-split-toggle.active,
.pane-split-toggle:hover {
  color: var(--text);
  border-color: var(--accent);
}

/* Pane layout toggle (content left/right flip) */
.pane-layout-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 12px;
  transition: color 0.1s, border-color 0.1s;
  flex-shrink: 0;
}
.pane-layout-toggle:hover {
  color: var(--text);
  border-color: var(--accent);
}

/* Tab move button */
.tab-move-btn {
  background: none;
  border: none;
  color: var(--text-dim, var(--text-muted));
  font-size: 12px;
  cursor: pointer;
  padding: 0 2px;
  opacity: 0;
  transition: opacity 0.15s;
  line-height: 1;
}
.tab-item:hover .tab-move-btn { opacity: 1; }
.tab-move-btn:hover { color: var(--accent); }

/* Empty pane placeholder */
.pane-empty {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-muted);
  font-size: 14px;
}

/* ── Lesson content viewer ───────────────────────────────────────────────── */

.lesson-content {
  flex: 1;
  overflow-y: auto;
  padding: 32px 40px;
  max-width: 900px;
  margin: 16px auto;
  width: 100%;
  box-sizing: border-box;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 10px;
}

.lesson-content-title {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text);
}

.lesson-content-type {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 10px;
  margin-bottom: 24px;
  background: var(--bg-hover);
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

.lesson-content-body {
  line-height: 1.7;
  color: var(--text);
}

.lesson-content-body img { max-width: 100%; height: auto; border-radius: 6px; }
.lesson-content-body p { margin: 0 0 1em; }
.lesson-content-body h1,
.lesson-content-body h2,
.lesson-content-body h3 { margin: 1.4em 0 0.5em; font-weight: 600; }
.lesson-content-body h1 { font-size: 1.4em; }
.lesson-content-body h2 { font-size: 1.2em; }
.lesson-content-body h3 { font-size: 1.05em; }
.lesson-content-body code {
  font-family: var(--font-mono, monospace);
  font-size: 0.875em;
  background: var(--bg-code, var(--bg-hover));
  padding: 1px 5px;
  border-radius: 4px;
}
.lesson-content-body pre {
  background: var(--bg-code, #1a1a2e);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 16px;
  overflow-x: auto;
  margin: 0 0 1em;
  position: relative;
}
.lesson-content-body pre code {
  background: none;
  padding: 0;
  font-size: 0.85em;
}
.lesson-content-body ul,
.lesson-content-body ol { margin: 0 0 1em 1.4em; }
.lesson-content-body li { margin-bottom: 0.25em; }
.lesson-content-body a { color: var(--accent); text-decoration: none; }
.lesson-content-body a:hover { text-decoration: underline; }
.lesson-content-body blockquote {
  border-left: 3px solid var(--accent);
  margin: 0 0 1em;
  padding: 8px 16px;
  color: var(--text-muted);
  background: var(--bg-hover);
  border-radius: 0 6px 6px 0;
}
.lesson-content-body table {
  display: block;
  overflow-x: auto;
  border-collapse: collapse;
  width: 100%;
  margin-bottom: 1em;
  font-size: 0.9em;
}
.lesson-content-body th,
.lesson-content-body td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
.lesson-content-body th { background: var(--bg-hover); font-weight: 600; }

.lesson-content-loading,
.lesson-content-error {
  text-align: center;
  color: var(--text-muted);
  font-size: 14px;
  padding: 48px 20px;
}
.lesson-content-error { color: #e57373; }

.slides-open-btn {
  display: inline-block;
  padding: 10px 22px;
  background: var(--accent, #6c63ff);
  color: #fff;
  border-radius: 6px;
  text-decoration: none;
  font-weight: 600;
  margin: 1.2em 0;
  transition: opacity 0.15s;
}
.slides-open-btn:hover { opacity: 0.8; }
.pdf-embed-wrapper {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 1em 0;
}
.pdf-embed {
  width: 100%;
  max-height: 80vh;
  min-height: 300px;
  border: none;
  border-radius: 6px;
  background: var(--bg-secondary, #1e1e2e);
}
.pdf-embed-fallback {
  align-self: flex-end;
  font-size: 0.85em;
  color: var(--text-muted, #888);
  text-decoration: none;
}
.pdf-embed-fallback:hover {
  color: var(--accent, #6c63ff);
}

/* Mobile: single pane only */
@media (max-width: 640px) {
  .pane-container.split #paneRight { display: none !important; }
  #paneDivider,
  .pane-split-toggle,
  .pane-layout-toggle { display: none !important; }
  .lesson-content { padding: 16px !important; }
  .modal-card { max-width: 90vw !important; }
  .pdf-embed { max-height: 60vh; min-height: 200px; }
}

/* Accessibility: respect user motion preferences */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}