:root {
  --bg-primary: #0f141c;
  --bg-secondary: #161e2b;
  --bg-card: rgba(26, 36, 51, 0.7);
  --bg-input: #101620;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-focus: #3b82f6;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --primary-accent: #3b82f6;
  --primary-gradient: linear-gradient(135deg, #3b82f6 0%, #2563eb 100%);
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --card-radius: 14px;
  --transition-speed: 0.2s;
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.35);

  /* Categorical Color Palette for Clear Visual Distinguishability */
  --cat-core-accent: #818cf8;
  --cat-core-bg: rgba(99, 102, 241, 0.14);
  --cat-core-border: rgba(99, 102, 241, 0.35);

  --cat-exam-accent: #38bdf8;
  --cat-exam-bg: rgba(56, 189, 248, 0.14);
  --cat-exam-border: rgba(56, 189, 248, 0.35);

  --cat-advantage-accent: #fbbf24;
  --cat-advantage-bg: rgba(245, 158, 11, 0.14);
  --cat-advantage-border: rgba(245, 158, 11, 0.35);

  --cat-system-accent: #94a3b8;
  --cat-system-bg: rgba(148, 163, 184, 0.14);
  --cat-system-border: rgba(148, 163, 184, 0.35);
}

body.light-theme {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-card-subtle: #f1f5f9;
  --bg-input: #ffffff;
  --border-color: #e2e8f0;
  --border-focus: #2563eb;
  --text-primary: #0f172a;
  --text-secondary: #334155;
  --text-muted: #64748b;
  --primary-accent: #2563eb;
  --primary-gradient: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
  --success-color: #059669;
  --warning-color: #d97706;
  --danger-color: #dc2626;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.06), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 25px -3px rgba(15, 23, 42, 0.08), 0 4px 6px -2px rgba(15, 23, 42, 0.04);

  /* Categorical Color Palette - Calibrated for Light Backgrounds */
  --cat-core-accent: #4338ca;
  --cat-core-bg: #eef2ff;
  --cat-core-border: #c7d2fe;

  --cat-exam-accent: #0284c7;
  --cat-exam-bg: #f0f9ff;
  --cat-exam-border: #bae6fd;

  --cat-advantage-accent: #b45309;
  --cat-advantage-bg: #fffbeb;
  --cat-advantage-border: #fde68a;

  --cat-system-accent: #334155;
  --cat-system-bg: #f1f5f9;
  --cat-system-border: #cbd5e1;
}

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

html {
  width: 100%;
  max-width: 100%;
  overflow-x: clip;
  overflow-x: hidden;
  touch-action: pan-y;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  min-height: var(--app-height, 100vh);
  min-height: 100dvh;
  width: 100%;
  max-width: 100%;
  display: flex;
  flex-direction: column;
  overflow-x: clip;
  overflow-x: hidden;
  touch-action: pan-y;
  position: relative;
}

.app-container {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: var(--app-height, 100vh);
  height: 100dvh;
  width: 100%;
  max-width: 100%;
  overflow-x: clip;
  overflow-x: hidden;
  overflow-y: hidden;
}

/* Header */
.app-header {
  height: 56px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  z-index: 20;
  width: 100%;
  max-width: 100%;
  box-sizing: border-box;
  flex-shrink: 0;
  transition: background-color 0.2s ease, border-color 0.2s ease;
}

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

.brand-logo {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: 12px;
  background: transparent;
  flex-shrink: 0;
  transition: transform var(--transition-speed);
}

.brand-logo:hover {
  transform: scale(1.05);
}

.brand-logo-img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  filter: drop-shadow(0 2px 8px rgba(79, 70, 229, 0.4));
}

.brand-title h1 {
  font-size: 1.18rem;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 6px;
}

.brand-accent {
  background: linear-gradient(135deg, #818cf8 0%, #38bdf8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  font-weight: 800;
}

.brand-title .subtext {
  font-size: 0.73rem;
  color: var(--text-secondary);
  font-weight: 500;
}

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

.status-badge {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  background: rgba(16, 185, 129, 0.15);
  color: var(--success-color);
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.status-badge.offline {
  background: rgba(245, 158, 11, 0.15);
  color: var(--warning-color);
  border-color: rgba(245, 158, 11, 0.3);
}

.status-badge .dot {
  font-size: 0.9rem;
}

/* App Body & Sidebar */
.app-body {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.sidebar {
  width: 270px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 16px 12px;
  overflow-y: auto;
  gap: 12px;
}

.mobile-cat-filter {
  display: none;
}

.sidebar-scrollable-content {
  display: flex;
  flex-direction: column;
  gap: 14px;
  flex: 1;
}

.nav-category-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.nav-category-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 4px 10px;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.cat-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  flex-shrink: 0;
}

.dot-core { background: var(--cat-core-accent); box-shadow: 0 0 6px var(--cat-core-accent); }
.dot-exam { background: var(--cat-exam-accent); box-shadow: 0 0 6px var(--cat-exam-accent); }
.dot-advantage { background: var(--cat-advantage-accent); box-shadow: 0 0 6px var(--cat-advantage-accent); }
.dot-system { background: var(--cat-system-accent); }

.nav-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: 9px;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 500;
  transition: all var(--transition-speed);
  border: 1px solid transparent;
}

.nav-item:hover {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.06);
}

.nav-item.active {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.22) 0%, rgba(37, 99, 235, 0.12) 100%);
  color: #ffffff;
  font-weight: 600;
  border-color: rgba(59, 130, 246, 0.45);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.nav-item[data-cat="exam"].active {
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.22) 0%, rgba(37, 99, 235, 0.12) 100%);
  border-color: rgba(6, 182, 212, 0.45);
  box-shadow: 0 4px 12px rgba(6, 182, 212, 0.2);
}

.nav-item[data-cat="advantage"].active {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.22) 0%, rgba(217, 119, 6, 0.12) 100%);
  border-color: rgba(245, 158, 11, 0.45);
  box-shadow: 0 4px 12px rgba(245, 158, 11, 0.2);
}

.nav-icon {
  font-size: 1.05rem;
  flex-shrink: 0;
}

.nav-label {
  flex: 1;
}

.nav-badge {
  font-size: 0.65rem;
  font-weight: 700;
  padding: 2px 7px;
  border-radius: 5px;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  font-family: var(--font-mono, monospace);
  flex-shrink: 0;
}

.badge-core {
  background: var(--cat-core-bg);
  color: var(--cat-core-accent);
  border: 1px solid var(--cat-core-border);
}

.badge-exam {
  background: var(--cat-exam-bg);
  color: var(--cat-exam-accent);
  border: 1px solid var(--cat-exam-border);
}

.badge-advantage {
  background: var(--cat-advantage-bg);
  color: var(--cat-advantage-accent);
  border: 1px solid var(--cat-advantage-border);
}

.badge-system {
  background: var(--cat-system-bg);
  color: var(--cat-system-accent);
  border: 1px solid var(--cat-system-border);
}

.sidebar-footer {
  border-top: 1px solid var(--border-color);
  padding-top: 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Content Stage */
.content-stage {
  flex: 1;
  overflow-y: auto;
  padding: 24px 32px;
  background-color: var(--bg-primary);
}

.tab-pane {
  display: none;
  max-width: 1200px;
  margin: 0 auto;
}

.tab-pane.active {
  display: block;
}

.pane-header {
  margin-bottom: 24px;
}

.pane-header h2 {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
}

.pane-header .subtitle {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* Cards & Layout */
.card {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 20px;
  box-shadow: var(--shadow-sm);
}

.grid-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.stat-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.stat-card.primary {
  border-color: rgba(59, 130, 246, 0.35);
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.12), rgba(37, 99, 235, 0.04));
}

.card-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.big-metric {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--text-primary);
}

.metric-sub {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.split-view {
  display: flex;
  gap: 20px;
}

.flex-1 {
  flex: 1;
}

/* ========================================================= */
/* Buttons System: Categorised, Distinguishable & Tactile */
/* ========================================================= */
.btn {
  padding: 8px 16px;
  border-radius: 9px;
  font-weight: 600;
  font-size: 0.88rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition-speed);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  user-select: none;
  text-decoration: none;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn:active {
  transform: translateY(1px);
}

.btn-primary {
  background: var(--primary-gradient);
  color: #fff;
  border-color: rgba(255, 255, 255, 0.15);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.35);
}

.btn-primary:hover {
  opacity: 0.95;
  box-shadow: 0 6px 16px rgba(59, 130, 246, 0.45);
}

.btn-hero-exam {
  background: linear-gradient(135deg, #06b6d4 0%, #2563eb 100%);
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 4px 14px rgba(6, 182, 212, 0.35);
}

.btn-hero-exam:hover {
  box-shadow: 0 6px 18px rgba(6, 182, 212, 0.5);
}

.btn-hero-advantage {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: #000000;
  font-weight: 700;
  border-color: rgba(255, 255, 255, 0.25);
  box-shadow: 0 4px 14px rgba(245, 158, 11, 0.35);
}

.btn-hero-advantage:hover {
  box-shadow: 0 6px 18px rgba(245, 158, 11, 0.5);
}

.btn-hero-audio {
  background: linear-gradient(135deg, #10b981 0%, #059669 100%);
  color: #ffffff;
  font-weight: 700;
  border-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 4px 14px rgba(16, 185, 129, 0.35);
}

.btn-hero-audio:hover {
  box-shadow: 0 6px 18px rgba(16, 185, 129, 0.5);
}

.btn-pulse {
  animation: pulseButtonGlow 2s infinite;
}

@keyframes pulseButtonGlow {
  0% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.6); }
  70% { box-shadow: 0 0 0 10px rgba(16, 185, 129, 0); }
  100% { box-shadow: 0 0 0 0 rgba(16, 185, 129, 0); }
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.14);
  border-color: rgba(255, 255, 255, 0.18);
}

.btn-outline {
  background: transparent;
  color: var(--primary-accent);
  border: 1px solid var(--primary-accent);
}

.btn-outline:hover {
  background: rgba(59, 130, 246, 0.1);
}

.btn-cat-ghost {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
}

.btn-cat-ghost:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.2);
}

.btn-sm {
  padding: 5px 12px;
  font-size: 0.78rem;
  border-radius: 7px;
}

.btn-icon {
  background: transparent;
  border: 1px solid var(--border-color);
  font-size: 1rem;
  padding: 6px 10px;
}

.btn-danger {
  background: rgba(239, 68, 68, 0.18);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.4);
}
.btn-danger:hover {
  background: var(--danger-color);
  color: #fff;
}

.btn-warning {
  background: rgba(245, 158, 11, 0.18);
  color: #fbbf24;
  border: 1px solid rgba(245, 158, 11, 0.4);
}
.btn-warning:hover {
  background: var(--warning-color);
  color: #fff;
}

.btn-success {
  background: rgba(16, 185, 129, 0.18);
  color: #34d399;
  border: 1px solid rgba(16, 185, 129, 0.4);
}
.btn-success:hover {
  background: var(--success-color);
  color: #fff;
}

/* Subcategory Toolbars & In-Module Segmented Buttons */
.sub-nav-bar {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  padding: 6px;
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: 12px;
}

.btn-sub-tool {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px;
  border-radius: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-secondary);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-sub-tool:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-primary);
}

.btn-sub-tool.active {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.3) 0%, rgba(56, 189, 248, 0.2) 100%);
  color: #ffffff;
  border-color: rgba(99, 102, 241, 0.55);
  box-shadow: 0 2px 10px rgba(99, 102, 241, 0.25);
}

.btn-sub-tool .tool-step {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  font-size: 0.68rem;
  font-weight: 800;
  background: rgba(255, 255, 255, 0.12);
  color: var(--text-primary);
}

.btn-sub-tool.active .tool-step {
  background: var(--primary-accent);
  color: #fff;
}

/* Chip Selector Bars (Topic, Passage, Essay Type, Exam Set) */
.chip-selector-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  margin: 10px 0;
}

.chip-label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-right: 4px;
}

.chip-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 13px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all 0.18s cubic-bezier(0.4, 0, 0.2, 1);
  white-space: nowrap;
}

.chip-btn:hover {
  background: rgba(255, 255, 255, 0.09);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.18);
  transform: translateY(-1px);
}

.chip-btn.active {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.25) 0%, rgba(56, 189, 248, 0.18) 100%);
  color: #ffffff;
  border-color: rgba(99, 102, 241, 0.6);
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.chat-quick-chips {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  align-items: center;
  padding: 10px 14px;
  background: rgba(0, 0, 0, 0.2);
  border-top: 1px solid var(--border-color);
}

/* Chat */
.chat-container {
  display: flex;
  flex-direction: column;
  height: 600px;
  padding: 16px;
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding-right: 8px;
}

.message {
  display: flex;
  max-width: 80%;
}

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

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

.msg-bubble {
  padding: 12px 18px;
  border-radius: 14px;
  font-size: 0.92rem;
  line-height: 1.5;
  white-space: pre-wrap;
}

.message.tutor .msg-bubble {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.message.user .msg-bubble {
  background: var(--primary-gradient);
  color: #fff;
}

.chat-input-bar {
  display: flex;
  gap: 10px;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border-color);
}

.chat-input-bar input, textarea {
  flex: 1;
  background: var(--bg-input);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 10px 14px;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.92rem;
  outline: none;
}

.chat-input-bar input:focus, textarea:focus {
  border-color: var(--border-focus);
}

/* Tasks list & Bars */
.tasks-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.task-item {
  padding: 12px 14px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.03);
  border-left: 4px solid var(--primary-accent);
}

.task-item strong {
  display: block;
  font-size: 0.9rem;
}

.task-item p {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.radar-bars {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.radar-bar-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
}

.bar-track {
  flex: 1;
  height: 8px;
  background: rgba(255,255,255,0.06);
  border-radius: 4px;
  margin: 0 12px;
  overflow: hidden;
}

.bar-fill {
  height: 100%;
  background: var(--primary-gradient);
  border-radius: 4px;
}

/* Flashcard */
.flashcard {
  border: 1px dashed var(--border-color);
  padding: 30px;
  border-radius: 12px;
  background: rgba(0,0,0,0.15);
  text-align: center;
  min-height: 180px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.report-box {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 16px;
  font-size: 0.9rem;
}

.mt-2 { margin-top: 8px; }
.mt-3 { margin-top: 14px; }
.mt-4 { margin-top: 20px; }
.my-3 { margin-top: 14px; margin-bottom: 14px; }

/* Responsive / Phone & Tablet Adaptive Layouts */
@media (min-width: 768px) {
  .app-body {
    flex-direction: row;
  }
  .sidebar {
    width: 260px;
    min-width: 240px;
    height: 100%;
  }
  .nav-links {
    flex-direction: column;
  }
  .reading-split {
    flex-direction: row;
    align-items: flex-start;
  }
  .passage-pane {
    flex: 1.2;
    max-height: 75vh;
    overflow-y: auto;
  }
  .questions-pane {
    flex: 1;
    max-height: 75vh;
    overflow-y: auto;
  }
}

/* =============================================================
   Developer Showcase Card (Settings Tab)
   ============================================================= */
.developer-showcase-card {
  background: linear-gradient(145deg, rgba(26, 36, 54, 0.85) 0%, rgba(17, 24, 39, 0.95) 100%);
  border: 1px solid rgba(99, 102, 241, 0.25);
  box-shadow: 0 16px 36px -8px rgba(0, 0, 0, 0.45), 0 0 20px rgba(99, 102, 241, 0.1);
  padding: clamp(16px, 3vw, 28px);
  position: relative;
  overflow: hidden;
}

.developer-showcase-card::before {
  content: "";
  position: absolute;
  top: -80px;
  right: -80px;
  width: 220px;
  height: 220px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, transparent 70%);
  pointer-events: none;
}

.developer-layout {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: clamp(16px, 3vw, 32px);
}

.developer-img-frame {
  position: relative;
  flex-shrink: 0;
  width: clamp(120px, 20vw, 170px);
  aspect-ratio: 4 / 5;
  border-radius: 18px;
  padding: 3px;
  background: linear-gradient(135deg, #6366f1 0%, #38bdf8 50%, #10b981 100%);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.4);
}

.developer-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center top;
  border-radius: 15px;
  display: block;
  background: #1e293b;
}

.developer-status-pill {
  position: absolute;
  bottom: -10px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(15, 23, 42, 0.92);
  border: 1px solid rgba(16, 185, 129, 0.4);
  color: #34d399;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  padding: 3px 10px;
  border-radius: 20px;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 5px;
  backdrop-filter: blur(8px);
}

.pulse-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: #10b981;
  box-shadow: 0 0 8px #10b981;
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

.developer-details {
  flex: 1;
  min-width: 0;
}

.badge-developer {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #818cf8;
  background: rgba(99, 102, 241, 0.12);
  padding: 3px 10px;
  border-radius: 6px;
  border: 1px solid rgba(99, 102, 241, 0.25);
  margin-bottom: 6px;
}

.developer-name {
  font-size: clamp(1.2rem, 2.5vw, 1.6rem);
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 8px;
  letter-spacing: -0.02em;
}

.developer-bio {
  font-size: 0.86rem;
  line-height: 1.55;
  color: var(--text-secondary);
  margin-bottom: 14px;
}

.developer-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.tag-pill {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.developer-specs-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 8px;
}

.spec-cell {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 8px 12px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.spec-label {
  font-size: 0.68rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.spec-value {
  font-size: 0.8rem;
  color: var(--text-primary);
  font-weight: 700;
}

/* =============================================================
   Screen Fit & Responsive Adaptations (Every Screen Size)
   ============================================================= */

/* High-Resolution Tablets & Desktop */
@media (min-width: 1024px) {
  .sidebar {
    width: 280px;
  }
  .grid-cards {
    grid-template-columns: repeat(4, 1fr);
  }
  .passage-pane {
    flex: 1.3;
  }
  .questions-pane {
    flex: 1;
  }
}

/* Tablets (Portrait & Mid Landscape 768px - 1023px) */
@media (min-width: 768px) and (max-width: 1023px) {
  .sidebar {
    width: 220px;
    padding: 12px 8px;
  }
  .nav-item {
    padding: 8px 10px;
    font-size: 0.84rem;
  }
  .grid-cards {
    grid-template-columns: repeat(2, 1fr);
  }
  .split-view {
    flex-direction: row;
    gap: 16px;
  }
  .passage-pane, .questions-pane {
    max-height: 65vh;
  }
}

/* Mobile & Small Screen (< 768px) */
@media (max-width: 767px) {
  .app-header {
    height: 52px;
    padding: 0 10px;
    gap: 6px;
    width: 100%;
    max-width: 100vw;
    box-sizing: border-box;
    overflow: hidden;
  }
  .header-brand {
    gap: 6px;
    flex-shrink: 0;
    min-width: 0;
  }
  .brand-logo {
    width: 32px;
    height: 32px;
    border-radius: 8px;
  }
  .brand-title h1 {
    font-size: 0.95rem;
    white-space: nowrap;
  }
  .brand-title .badge {
    padding: 1px 5px;
    font-size: 0.65rem;
  }
  .brand-title .subtext {
    display: none;
  }
  .header-controls {
    gap: 5px;
    flex-shrink: 1;
    min-width: 0;
    justify-content: flex-end;
  }
  .status-badge {
    padding: 3px 7px;
    font-size: 0.68rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  #toggleOfflineBtn {
    padding: 3px 7px;
    font-size: 0.68rem;
    white-space: nowrap;
    flex-shrink: 0;
  }
  #themeToggleBtn {
    padding: 3px 7px;
    font-size: 0.85rem;
    flex-shrink: 0;
  }
  .app-body {
    flex-direction: column;
    width: 100%;
    max-width: 100%;
    overflow-x: hidden;
  }
  .sidebar {
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    height: auto;
    flex-shrink: 0;
    border-right: none;
    border-bottom: 1px solid var(--border-color);
    padding: 6px 10px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    overflow: visible;
  }
  .mobile-cat-filter {
    display: flex;
    gap: 4px;
    padding: 3px;
    background: rgba(0, 0, 0, 0.35);
    border-radius: 8px;
    margin-bottom: 6px;
    width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
  }
  .mobile-cat-filter::-webkit-scrollbar {
    display: none;
  }
  .cat-filter-btn {
    flex: 1 1 0;
    min-width: 0;
    padding: 6px 3px;
    font-size: 0.70rem;
    font-weight: 700;
    border-radius: 6px;
    border: 1px solid transparent;
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    white-space: nowrap;
    text-align: center;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: all 0.15s ease;
  }
  .cat-filter-btn.active {
    background: var(--bg-card);
    color: var(--text-primary);
    border-color: rgba(255, 255, 255, 0.18);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.35);
  }
  .sidebar-scrollable-content {
    flex-direction: row;
    display: flex;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    gap: 6px;
    scrollbar-width: thin;
    padding-bottom: 2px;
  }
  .sidebar-scrollable-content::-webkit-scrollbar {
    height: 3px;
  }
  .sidebar-scrollable-content::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.2);
    border-radius: 3px;
  }
  .nav-category-group {
    flex-direction: row;
    display: flex;
    align-items: center;
    gap: 4px;
    flex-shrink: 0;
  }
  .nav-category-header {
    display: none;
  }
  .nav-links {
    flex-direction: row;
    display: flex;
    gap: 4px;
    flex-shrink: 0;
  }
  .nav-item {
    flex-shrink: 0;
    padding: 6px 10px;
    font-size: 0.78rem;
    white-space: nowrap;
    border-radius: 8px;
  }
  .nav-item .nav-badge {
    display: none; /* keep mobile navigation compact */
  }
  .sidebar-footer {
    display: none;
  }
  .content-stage {
    padding: 12px;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    overflow-x: hidden;
  }
  .grid-cards {
    grid-template-columns: 1fr;
    gap: 10px;
  }
  .split-view {
    flex-direction: column;
    gap: 12px;
  }
  .passage-pane, .questions-pane {
    max-height: none;
    overflow-y: visible;
  }
  .developer-layout {
    flex-direction: column;
    text-align: center;
  }
  .developer-img-frame {
    width: 130px;
    margin: 0 auto;
  }
  .developer-tags {
    justify-content: center;
  }
  .developer-specs-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Extra Small Phones (< 380px) */
@media (max-width: 380px) {
  .app-header {
    height: 48px;
    padding: 0 8px;
  }
  .brand-title h1 {
    font-size: 0.95rem;
  }
  .status-badge span:not(.dot) {
    display: none;
  }
  .developer-specs-grid {
    grid-template-columns: 1fr;
  }
}

/* Interactive IELTS Speaking Examiner Room */
.interview-stepper {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 8px;
  margin-bottom: 14px;
}
.step-badge {
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.78rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  white-space: nowrap;
  transition: all var(--transition-speed);
}
.step-badge.active {
  background: var(--primary-gradient);
  color: #ffffff;
  border-color: transparent;
  box-shadow: 0 2px 8px rgba(59, 130, 246, 0.4);
}
.examiner-stage-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.examiner-profile-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.examiner-avatar-group {
  display: flex;
  align-items: center;
  gap: 12px;
}
.examiner-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  box-shadow: 0 4px 12px rgba(79, 70, 229, 0.3);
}
.examiner-info h4 {
  font-size: 0.98rem;
  font-weight: 700;
  color: var(--text-primary);
}
.examiner-info span {
  font-size: 0.75rem;
  color: var(--text-secondary);
}
.examiner-speech-bubble {
  background: rgba(59, 130, 246, 0.08);
  border: 1px solid rgba(59, 130, 246, 0.25);
  border-left: 4px solid var(--primary-accent);
  border-radius: 10px;
  padding: 12px 14px;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--text-primary);
}
.interview-dialogue-history {
  max-height: 180px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 6px 0;
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}
.dialogue-turn {
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 0.86rem;
  line-height: 1.45;
}
.dialogue-turn.examiner {
  background: rgba(255, 255, 255, 0.04);
  border-left: 3px solid var(--primary-accent);
}
.dialogue-turn.candidate {
  background: rgba(16, 185, 129, 0.08);
  border-left: 3px solid var(--success-color);
}
.prep-timer-card {
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-radius: 10px;
  padding: 12px;
}
.band-upgrade-box {
  background: rgba(129, 140, 248, 0.08);
  border: 1px solid rgba(129, 140, 248, 0.25);
  border-radius: 10px;
  padding: 12px;
  margin-top: 10px;
}
.upgrade-item {
  background: rgba(255, 255, 255, 0.03);
  border-radius: 8px;
  padding: 10px;
  margin-top: 8px;
}
.upgrade-item strong {
  color: #38bdf8;
}



/* ========================================================= */
/* IELTS Advantage & Enhanced Interactive Modules Styling    */
/* ========================================================= */

.sub-nav-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  padding: 4px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
}

.sub-nav-bar .btn {
  font-size: 0.82rem;
  padding: 6px 12px;
  transition: all 0.2s ease;
}

.advantage-pill-banner {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  background: linear-gradient(90deg, rgba(79, 70, 229, 0.15) 0%, rgba(6, 182, 212, 0.12) 100%);
  border: 1px solid rgba(79, 70, 229, 0.3);
  border-radius: 10px;
  font-size: 0.88rem;
  color: #38bdf8;
}

.section-title-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

.badge-step {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 2px 8px;
  border-radius: 4px;
  background: var(--primary-accent);
  color: #fff;
  margin-bottom: 6px;
}

.analysis-breakdown-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
}

.breakdown-card {
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 14px;
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.breakdown-card:hover {
  border-color: rgba(99, 102, 241, 0.4);
  transform: translateY(-2px);
}

.breakdown-card h4 {
  font-size: 0.95rem;
  margin-bottom: 6px;
}

.highlight-text {
  font-weight: 600;
  color: #38bdf8;
  font-size: 0.92rem;
  line-height: 1.45;
}

.sub-hint {
  display: block;
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 6px;
  line-height: 1.35;
}

.callout-card {
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-left: 4px solid #f59e0b;
  border-radius: 8px;
  padding: 12px 14px;
  font-size: 0.88rem;
  line-height: 1.5;
}

.callout-card h4 {
  color: #fbbf24;
  margin-bottom: 4px;
  font-size: 0.92rem;
}

/* PEEL Interactive Grid */
.peel-interactive-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 12px;
}

.peel-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 14px;
  position: relative;
}

.peel-tag {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 6px;
  font-size: 0.78rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.peel-card.point .peel-tag { background: #4f46e5; color: #fff; }
.peel-card.explain .peel-tag { background: #0891b2; color: #fff; }
.peel-card.example .peel-tag { background: #16a34a; color: #fff; }
.peel-card.link .peel-tag { background: #d97706; color: #fff; }

.peel-content {
  font-size: 0.88rem;
  line-height: 1.5;
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.03);
  padding: 10px;
  border-radius: 6px;
  margin-top: 8px;
}

/* Checklist Container */
.checklist-container {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.check-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-size: 0.88rem;
  cursor: pointer;
  transition: background 0.2s ease;
}

.check-item:hover {
  background: rgba(255, 255, 255, 0.05);
}

.check-item input[type="checkbox"] {
  margin-top: 2px;
  cursor: pointer;
}

.progress-bar-container {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.progress-bar-track {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 4px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, #4f46e5, #10b981);
  transition: width 0.3s ease;
}

/* Grammar Fill-Up Clozes */
.fillup-stats-badge {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  padding: 6px 12px;
  border-radius: 20px;
  font-size: 0.85rem;
}

.fillup-grid {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.cloze-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 16px;
  transition: border-color 0.2s ease;
}

.cloze-card.correct {
  border-color: #10b981;
  background: rgba(16, 185, 129, 0.03);
}

.cloze-card.incorrect {
  border-color: #ef4444;
  background: rgba(239, 68, 68, 0.03);
}

.cloze-prompt {
  font-size: 0.96rem;
  line-height: 1.5;
  color: var(--text-primary);
}

.cloze-input-row {
  display: flex;
  gap: 8px;
  margin-top: 10px;
  align-items: center;
  flex-wrap: wrap;
}

.cloze-input {
  flex: 1;
  min-width: 180px;
  padding: 8px 12px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 0.92rem;
}

.cloze-feedback {
  margin-top: 10px;
  padding: 10px 12px;
  border-radius: 6px;
  font-size: 0.85rem;
  line-height: 1.45;
}

.cloze-feedback.success {
  background: rgba(16, 185, 129, 0.1);
  color: #34d399;
  border: 1px solid rgba(16, 185, 129, 0.2);
}

.cloze-feedback.error {
  background: rgba(239, 68, 68, 0.1);
  color: #f87171;
  border: 1px solid rgba(239, 68, 68, 0.2);
}

/* Collocation Game Grid */
.collocation-game-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 12px;
}

.collocation-card {
  background: rgba(255, 255, 255, 0.025);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 14px;
}

.collocation-verb {
  font-size: 1.05rem;
  font-weight: 700;
  color: #818cf8;
}

.collocation-noun-slot {
  margin-top: 6px;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.collocation-example {
  margin-top: 6px;
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-style: italic;
}

/* Upgrades Table */
.upgrades-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.upgrades-table th, .upgrades-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border-color);
  text-align: left;
}

.upgrades-table th {
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-secondary);
  font-weight: 600;
}

.upgrades-table tr:hover {
  background: rgba(255, 255, 255, 0.02);
}

/* Synonym Table */
.synonym-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.86rem;
  background: rgba(59, 130, 246, 0.04);
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid rgba(59, 130, 246, 0.2);
}

.synonym-table th, .synonym-table td {
  padding: 8px 12px;
  border-bottom: 1px solid rgba(59, 130, 246, 0.15);
}

.synonym-table th {
  background: rgba(59, 130, 246, 0.12);
  color: #60a5fa;
  font-weight: 600;
}

/* ========================================================= */
/* Daily Goal Achiever & Category Progress Dashboard (v1.4.0) */
/* ========================================================= */

/* Daily Goal Mission Card */
.daily-goal-card {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.12) 0%, rgba(59, 130, 246, 0.05) 50%, var(--bg-card) 100%);
  border: 1px solid rgba(99, 102, 241, 0.35);
  border-radius: var(--card-radius);
  padding: 20px 24px;
  position: relative;
  overflow: hidden;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.12);
}

.daily-goal-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, #6366f1, #06b6d4, #10b981, #f59e0b);
}

.goal-header-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 12px;
}

.goal-title-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
}

.goal-icon-badge {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.3), rgba(6, 182, 212, 0.2));
  border: 1px solid rgba(99, 102, 241, 0.4);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  box-shadow: 0 0 12px rgba(99, 102, 241, 0.3);
}

.goal-chips-row {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.goal-chip {
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  cursor: pointer;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.goal-chip:hover {
  background: rgba(99, 102, 241, 0.12);
  color: var(--text-primary);
  border-color: rgba(99, 102, 241, 0.4);
  transform: translateY(-1px);
}

.goal-chip.active {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.3) 0%, rgba(6, 182, 212, 0.2) 100%);
  color: #ffffff;
  border-color: #818cf8;
  box-shadow: 0 2px 10px rgba(99, 102, 241, 0.35);
}

.goal-active-box {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 12px;
  padding: 14px 18px;
  margin-top: 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
}

.goal-target-details {
  flex: 1;
  min-width: 240px;
}

.goal-target-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.goal-target-desc {
  font-size: 0.84rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

.goal-progress-bar-wrap {
  margin-top: 8px;
  width: 100%;
}

.goal-progress-track {
  height: 8px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}

.goal-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #6366f1, #06b6d4, #10b981);
  border-radius: 4px;
  transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.5);
}

.goal-actions-group {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.btn-achieve-goal {
  background: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
  color: #ffffff;
  border: none;
  font-weight: 700;
  padding: 10px 18px;
  border-radius: 9px;
  box-shadow: 0 4px 14px rgba(79, 70, 229, 0.4);
  cursor: pointer;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.btn-achieve-goal:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(79, 70, 229, 0.55);
}

.btn-achieve-goal:active {
  transform: translateY(1px);
}

/* Category Progress Dashboard Grid */
.category-progress-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
  margin-top: 24px;
}

.cat-progress-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--card-radius);
  padding: 18px 20px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 12px;
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}

.cat-progress-card:hover {
  border-color: rgba(255, 255, 255, 0.16);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.cat-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.cat-badge-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.cat-progress-percent {
  font-size: 1.15rem;
  font-weight: 800;
  font-family: var(--font-mono, monospace);
}

.cat-progress-card[data-cat="core"] .cat-progress-percent { color: var(--cat-core-accent); }
.cat-progress-card[data-cat="exam"] .cat-progress-percent { color: var(--cat-exam-accent); }
.cat-progress-card[data-cat="advantage"] .cat-progress-percent { color: var(--cat-advantage-accent); }
.cat-progress-card[data-cat="system"] .cat-progress-percent { color: var(--cat-system-accent); }

.cat-metrics-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.83rem;
  color: var(--text-secondary);
}

.cat-metric-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 4px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.cat-metric-item strong {
  color: var(--text-primary);
}

.cat-progress-track {
  height: 6px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 3px;
  overflow: hidden;
}

.cat-progress-bar {
  height: 100%;
  border-radius: 3px;
  transition: width 0.5s ease;
}

.bar-core { background: linear-gradient(90deg, #3b82f6, #60a5fa); box-shadow: 0 0 8px rgba(59, 130, 246, 0.5); }
.bar-exam { background: linear-gradient(90deg, #06b6d4, #34d399); box-shadow: 0 0 8px rgba(6, 182, 212, 0.5); }
.bar-advantage { background: linear-gradient(90deg, #f59e0b, #fbbf24); box-shadow: 0 0 8px rgba(245, 158, 11, 0.5); }
.bar-system { background: linear-gradient(90deg, #a855f7, #c084fc); box-shadow: 0 0 8px rgba(168, 85, 247, 0.5); }

/* Band Score Live Toast Notification */
.band-update-toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 99999;
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(52, 211, 153, 0.4);
  border-radius: 12px;
  padding: 14px 20px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.5), 0 0 20px rgba(52, 211, 153, 0.2);
  display: flex;
  align-items: center;
  gap: 14px;
  color: var(--text-primary);
  max-width: 380px;
  transform: translateY(100px);
  opacity: 0;
  transition: all 0.35s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  pointer-events: none;
}

.band-update-toast.show {
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.toast-icon {
  font-size: 1.6rem;
  flex-shrink: 0;
}

.toast-title {
  font-weight: 700;
  font-size: 0.95rem;
  color: #34d399;
}

.toast-subtitle {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

/* On-Startup Welcome Goal Modal */
.goal-modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 16px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.goal-modal-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

.goal-modal-card {
  background: var(--bg-card);
  border: 1px solid rgba(99, 102, 241, 0.4);
  border-radius: 16px;
  max-width: 520px;
  width: 100%;
  padding: 26px 28px;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.6), 0 0 24px rgba(99, 102, 241, 0.2);
  transform: scale(0.92);
  transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

.goal-modal-overlay.open .goal-modal-card {
  transform: scale(1);
}

/* ========================================================================= */
/* Multi-Platform (Tablet, iOS, Windows) & Auto Screen Size Adjustment (v1.5)*/
/* ========================================================================= */

/* Root Environment Insets for iOS & Android Notches */
:root {
  --sat: env(safe-area-inset-top, 0px);
  --sar: env(safe-area-inset-right, 0px);
  --sab: env(safe-area-inset-bottom, 0px);
  --sal: env(safe-area-inset-left, 0px);
}

html {
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  scroll-behavior: smooth;
}

body {
  overscroll-behavior-y: contain;
  padding: 0;
  margin: 0;
}

/* iOS Specific Touch Acceleration */

.platform-ios .content-stage,
.platform-ios .sidebar,
.platform-ios .passage-pane,
.platform-ios .questions-pane {
  -webkit-overflow-scrolling: touch;
}

/* Universal Modern Scrollbars (Windows Fluent & Clean Mac/Linux) */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

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

::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.28);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: rgba(148, 163, 184, 0.48);
}

body.light-theme ::-webkit-scrollbar-track {
  background: #f8fafc;
}

body.light-theme ::-webkit-scrollbar-thumb {
  background: #cbd5e1;
}

body.light-theme ::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

* {
  scrollbar-width: thin;
  scrollbar-color: rgba(148, 163, 184, 0.28) var(--bg-primary);
}

body.light-theme * {
  scrollbar-color: #cbd5e1 #f8fafc;
}

/* Tablet Layout Enhancements (768px - 1180px - iPads & Android Tablets) */
@media (min-width: 768px) and (max-width: 1180px) {
  .app-body {
    flex-direction: row;
  }
  .sidebar {
    width: 230px;
    min-width: 210px;
    padding: 14px 10px;
  }
  .content-stage {
    padding: 20px 22px;
  }
  .grid-cards {
    grid-template-columns: repeat(2, 1fr);
  }
  .category-progress-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .reading-split {
    flex-direction: row;
    gap: 16px;
  }
  .passage-pane {
    flex: 1.15;
    max-height: 78vh;
  }
  .questions-pane {
    flex: 0.85;
    max-height: 78vh;
  }
  .analysis-breakdown-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .peel-interactive-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .split-view {
    flex-direction: column;
  }
}

/* Desktop & Windows Wide Viewports (1181px - 1600px) */
@media (min-width: 1181px) {
  .tab-pane {
    max-width: 1360px;
  }
  .content-stage {
    padding: 26px 36px;
  }
  .grid-cards {
    grid-template-columns: repeat(4, 1fr);
  }
  .category-progress-grid {
    grid-template-columns: repeat(4, 1fr);
  }
  .reading-split {
    gap: 24px;
  }
}

/* Ultrawide 4K & Productivity Monitors (> 1600px) */
@media (min-width: 1600px) {
  .tab-pane {
    max-width: 1540px;
  }
  .content-stage {
    padding: 32px 48px;
  }
}

/* ========================================================================= */
/* Comprehensive Light Mode Refinements & High-Contrast Visual Experience    */
/* ========================================================================= */

body.light-theme {
  background-color: var(--bg-primary);
  color: var(--text-primary);
}

body.light-theme .app-header {
  background: #ffffff;
  border-bottom: 1px solid #e2e8f0;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.04);
}

body.light-theme .sidebar {
  background: #ffffff;
  border-right: 1px solid #e2e8f0;
}

body.light-theme .sidebar-footer {
  border-top: 1px solid #e2e8f0;
  color: #64748b;
}

body.light-theme .nav-category-header {
  color: #64748b;
}

body.light-theme .nav-item {
  color: #475569;
}

body.light-theme .nav-item:hover {
  background: #f1f5f9;
  color: #0f172a;
  border-color: #e2e8f0;
}

body.light-theme .nav-item.active {
  background: #eff6ff;
  color: #1d4ed8;
  border-color: #93c5fd;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.12);
  font-weight: 700;
}

body.light-theme .nav-item[data-cat="exam"].active {
  background: #f0f9ff;
  color: #0369a1;
  border-color: #7dd3fc;
  box-shadow: 0 2px 8px rgba(2, 132, 199, 0.12);
}

body.light-theme .nav-item[data-cat="advantage"].active {
  background: #fffbeb;
  color: #b45309;
  border-color: #fcd34d;
  box-shadow: 0 2px 8px rgba(217, 119, 6, 0.12);
}

/* Cards & Containers in Light Mode */
body.light-theme .card,
body.light-theme .stat-card,
body.light-theme .cat-progress-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05), 0 4px 12px rgba(15, 23, 42, 0.03);
}

body.light-theme .card:hover,
body.light-theme .cat-progress-card:hover {
  border-color: #cbd5e1;
  box-shadow: 0 4px 16px rgba(15, 23, 42, 0.08);
}

body.light-theme .stat-card.primary {
  background: linear-gradient(135deg, #eff6ff 0%, #ffffff 100%);
  border-color: #bfdbfe;
}

body.light-theme .card-label {
  color: #64748b;
}

body.light-theme .big-metric {
  color: #0f172a;
}

body.light-theme .metric-sub {
  color: #475569;
}

/* Button Contrast in Light Mode */
body.light-theme .btn-secondary {
  background: #f1f5f9;
  color: #1e293b;
  border: 1px solid #cbd5e1;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
}

body.light-theme .btn-secondary:hover {
  background: #e2e8f0;
  color: #0f172a;
  border-color: #94a3b8;
}

body.light-theme .btn-outline {
  background: #ffffff;
  color: #2563eb;
  border: 1.5px solid #2563eb;
}

body.light-theme .btn-outline:hover {
  background: #eff6ff;
  color: #1d4ed8;
}

body.light-theme .btn-cat-ghost {
  background: #f8fafc;
  color: #334155;
  border: 1px solid #e2e8f0;
}

body.light-theme .btn-cat-ghost:hover {
  background: #f1f5f9;
  color: #0f172a;
  border-color: #cbd5e1;
}

body.light-theme .btn-icon {
  background: #f8fafc;
  border: 1px solid #cbd5e1;
  color: #1e293b;
}

body.light-theme .btn-icon:hover {
  background: #e2e8f0;
  color: #0f172a;
}

body.light-theme .btn-hero-exam {
  background: linear-gradient(135deg, #0284c7 0%, #1d4ed8 100%);
  color: #ffffff;
  border: none;
}

body.light-theme .btn-hero-advantage {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: #ffffff;
  border: none;
  text-shadow: 0 1px 2px rgba(0,0,0,0.25);
}

body.light-theme .btn-hero-audio {
  background: linear-gradient(135deg, #059669 0%, #047857 100%);
  color: #ffffff;
  border: none;
}

body.light-theme .btn-danger {
  background: #fef2f2;
  color: #dc2626;
  border-color: #fca5a5;
}

body.light-theme .btn-warning {
  background: #fffbeb;
  color: #b45309;
  border-color: #fde68a;
}

body.light-theme .btn-success {
  background: #f0fdf4;
  color: #15803d;
  border-color: #86efac;
}

/* Filter & Chips in Light Mode */
body.light-theme .mobile-cat-filter {
  background: #e2e8f0;
  border: 1px solid #cbd5e1;
}

body.light-theme .cat-filter-btn {
  background: #ffffff;
  color: #334155;
  border: 1px solid #cbd5e1;
}

body.light-theme .cat-filter-btn:hover {
  background: #e2e8f0;
  color: #0f172a;
}

body.light-theme .cat-filter-btn.active {
  background: #2563eb;
  color: #ffffff;
  border-color: #1d4ed8;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
}

body.light-theme .chip-label {
  color: #64748b;
}

body.light-theme .chip-btn,
body.light-theme .goal-chip {
  background: #f8fafc;
  color: #334155;
  border: 1px solid #cbd5e1;
  font-weight: 600;
}

body.light-theme .chip-btn:hover,
body.light-theme .goal-chip:hover {
  background: #e2e8f0;
  color: #0f172a;
  border-color: #94a3b8;
}

body.light-theme .chip-btn.active,
body.light-theme .goal-chip.active {
  background: linear-gradient(135deg, #2563eb 0%, #1d4ed8 100%);
  color: #ffffff;
  border-color: #1d4ed8;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
}

body.light-theme .sub-nav-bar {
  background: #f1f5f9;
  border: 1px solid #e2e8f0;
}

body.light-theme .btn-sub-tool {
  background: #ffffff;
  color: #475569;
  border: 1px solid #e2e8f0;
}

body.light-theme .btn-sub-tool:hover {
  background: #f8fafc;
  color: #0f172a;
  border-color: #cbd5e1;
}

body.light-theme .btn-sub-tool.active {
  background: #2563eb;
  color: #ffffff;
  border-color: #1d4ed8;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.2);
}

body.light-theme .btn-sub-tool .tool-step {
  background: #e2e8f0;
  color: #1e293b;
}

body.light-theme .btn-sub-tool.active .tool-step {
  background: #ffffff;
  color: #1d4ed8;
}

/* Inputs, Textareas, Selects in Light Mode */
body.light-theme input,
body.light-theme textarea,
body.light-theme select,
body.light-theme .cloze-input,
body.light-theme .chat-input-bar input {
  background: #ffffff !important;
  color: #0f172a !important;
  border: 1.5px solid #cbd5e1 !important;
  box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.04);
}

body.light-theme input:focus,
body.light-theme textarea:focus,
body.light-theme select:focus,
body.light-theme .cloze-input:focus,
body.light-theme .chat-input-bar input:focus {
  border-color: #2563eb !important;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15) !important;
}

body.light-theme input::placeholder,
body.light-theme textarea::placeholder {
  color: #94a3b8;
}

/* Daily Goal Mission Card in Light Mode */
body.light-theme .daily-goal-card {
  background: linear-gradient(135deg, #ffffff 0%, #f0fdf4 50%, #eff6ff 100%);
  border: 1.5px solid #bfdbfe;
  box-shadow: 0 4px 18px rgba(37, 99, 235, 0.08);
}

body.light-theme .goal-active-box {
  background: #ffffff;
  border: 1px solid #cbd5e1;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.04);
}

body.light-theme .goal-progress-track {
  background: #e2e8f0;
}

/* Category Progress Dashboard in Light Mode */
body.light-theme .cat-progress-card[data-cat="core"] {
  border-color: #c7d2fe;
}
body.light-theme .cat-progress-card[data-cat="exam"] {
  border-color: #bae6fd;
}
body.light-theme .cat-progress-card[data-cat="advantage"] {
  border-color: #fde68a;
}
body.light-theme .cat-progress-card[data-cat="system"] {
  border-color: #cbd5e1;
}

body.light-theme .cat-metric-item {
  border-bottom: 1px solid #f1f5f9;
}

body.light-theme .cat-progress-track {
  background: #e2e8f0;
}

/* Reading & Listening Panes in Light Mode */
body.light-theme .passage-pane,
body.light-theme .questions-pane {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
}

body.light-theme .reading-text {
  color: #1e293b;
  line-height: 1.8;
}

body.light-theme .question-item {
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  color: #0f172a;
}

body.light-theme .synonym-table {
  background: #f0fdf4;
  border: 1px solid #bbf7d0;
}

body.light-theme .synonym-table th {
  background: #dcfce7;
  color: #15803d;
}

body.light-theme .synonym-table td {
  border-bottom: 1px solid #dcfce7;
  color: #166534;
}

/* Speaking Room in Light Mode */
body.light-theme .examiner-stage-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
}

body.light-theme .examiner-speech-bubble {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  border-left: 4px solid #2563eb;
  color: #0f172a;
}

body.light-theme .dialogue-turn.examiner {
  background: #f8fafc;
  border-left: 3px solid #2563eb;
  color: #1e293b;
}

body.light-theme .dialogue-turn.candidate {
  background: #f0fdf4;
  border-left: 3px solid #10b981;
  color: #14532d;
}

body.light-theme .speaking-cue-card {
  background: #fffdf5;
  border: 1.5px solid #fde68a;
  color: #1e293b;
  box-shadow: 0 4px 14px rgba(217, 119, 6, 0.08);
}

body.light-theme .prep-timer-card {
  background: #fffbeb;
  border: 1px solid #fde68a;
  color: #92400e;
}

body.light-theme .band-upgrade-box {
  background: #eef2ff;
  border: 1px solid #c7d2fe;
}

body.light-theme .upgrade-item {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  color: #334155;
}

body.light-theme .upgrade-item strong {
  color: #0369a1;
}

/* Writing Studio & Advantage Framework in Light Mode */
body.light-theme .advantage-pill-banner {
  background: linear-gradient(90deg, #eef2ff 0%, #f0f9ff 100%);
  border: 1px solid #c7d2fe;
  color: #1d4ed8;
}

body.light-theme .breakdown-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light-theme .breakdown-card:hover {
  border-color: #93c5fd;
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.08);
}

body.light-theme .highlight-text {
  color: #0284c7;
}

body.light-theme .callout-card {
  background: #fffbeb;
  border: 1px solid #fde68a;
  border-left: 4px solid #d97706;
  color: #78350f;
}

body.light-theme .callout-card h4 {
  color: #b45309;
}

body.light-theme .peel-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light-theme .peel-content {
  background: #f8fafc;
  color: #1e293b;
  border: 1px solid #e2e8f0;
}

body.light-theme .check-item {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  color: #1e293b;
}

body.light-theme .check-item:hover {
  background: #f8fafc;
  border-color: #cbd5e1;
}

body.light-theme .progress-bar-track {
  background: #e2e8f0;
}

body.light-theme .cloze-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light-theme .collocation-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
}

body.light-theme .collocation-verb {
  color: #4338ca;
}

body.light-theme .upgrades-table th {
  background: #f1f5f9;
  color: #334155;
  border-bottom: 1.5px solid #cbd5e1;
}

body.light-theme .upgrades-table td {
  border-bottom: 1px solid #e2e8f0;
  color: #1e293b;
}

body.light-theme .upgrades-table tr:hover {
  background: #f8fafc;
}

/* Chat in Light Mode */
body.light-theme .chat-quick-chips {
  background: #f8fafc;
  border-top: 1px solid #e2e8f0;
}

body.light-theme .message.tutor .msg-bubble {
  background: #f1f5f9;
  border: 1px solid #e2e8f0;
  color: #0f172a;
}

body.light-theme .flashcard {
  background: #f8fafc;
  border: 1.5px dashed #cbd5e1;
}

body.light-theme .report-box {
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  color: #1e293b;
}

body.light-theme .developer-showcase-card {
  background: linear-gradient(145deg, #ffffff 0%, #f8fafc 100%);
  border: 1px solid #c7d2fe;
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.08);
}

body.light-theme .developer-showcase-card::before {
  background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 70%);
}

/* Toast & Modals in Light Mode */
body.light-theme .band-update-toast {
  background: #ffffff;
  border: 1.5px solid #10b981;
  color: #0f172a;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.12), 0 0 16px rgba(16, 185, 129, 0.15);
}

body.light-theme .goal-modal-overlay {
  background: rgba(15, 23, 42, 0.4);
}

body.light-theme .goal-modal-card {
  background: #ffffff;
  border: 1.5px solid #bfdbfe;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15), 0 0 24px rgba(37, 99, 235, 0.12);
  color: #0f172a;
}