/* ==========================================
   CBSE CLASS 9 & 10 STUDY TRACKER
   Design System & Stylesheet — Sunil Bhaiya Edition
   ========================================== */

:root {
  /* Color Palette - Neutral Slate Base */
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --bg-elevated: #f1f5f9;
  --surface-secondary: #f1f5f9;
  --bg-input: #ffffff;
  --border-color: #e2e8f0;
  --border-focus: #0284c7;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  --accent-primary: #0284c7;
  --accent-hover: #0369a1;
  --accent-light: #e0f2fe;

  /* Status Colors */
  --status-green: #10b981;
  --status-green-bg: #ecfdf5;
  --status-green-border: #a7f3d0;

  --status-amber: #f59e0b;
  --status-amber-bg: #fffbeb;
  --status-amber-border: #fde68a;

  --status-red: #ef4444;
  --status-red-bg: #fef2f2;
  --status-red-border: #fca5a5;

  --status-grey: #64748b;
  --status-grey-bg: #f1f5f9;
  --status-grey-border: #cbd5e1;

  /* Stage Colors */
  --stage-none: #e2e8f0;
  --stage-progress: #f59e0b;
  --stage-done: #10b981;

  /* Elevation Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  /* Font System */
  --font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-size-sm: 0.875rem; /* 14px */
  --font-size-base: 1rem;    /* 16px min */
  --font-size-lg: 1.125rem;  /* 18px */
  --font-size-xl: 1.25rem;   /* 20px */
  --font-size-2xl: 1.5rem;   /* 24px */

  /* Touch Minimum */
  --touch-min: 44px;
}

/* Dark Mode Override */
html.dark, body.dark {
  --bg-main: #0f172a;
  --bg-card: #1e293b;
  --bg-elevated: #334155;
  --surface-secondary: #1e293b;
  --bg-input: #1e293b;
  --border-color: #334155;
  --border-focus: #38bdf8;

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-inverse: #0f172a;

  --accent-primary: #38bdf8;
  --accent-hover: #7dd3fc;
  --accent-light: #0c4a6e;

  --status-green-bg: #064e3b;
  --status-green-border: #047857;

  --status-amber-bg: #78350f;
  --status-amber-border: #b45309;

  --status-red-bg: #7f1d1d;
  --status-red-border: #b91c1c;

  --status-grey-bg: #334155;
  --status-grey-border: #475569;

  --stage-none: #334155;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.6);
}

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

html, body {
  width: 100%;
  min-height: 100vh;
  min-height: 100dvh;
  background-color: var(--bg-main);
  color: var(--text-primary);
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  min-height: 100dvh;
}

/* Container Structure */
.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: var(--font-size-lg);
}

.brand-icon {
  width: 32px;
  height: 32px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.profile-select-wrapper select {
  min-height: var(--touch-min);
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--bg-input);
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  font-weight: 600;
}

.app-main {
  flex: 1;
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem 1rem 5rem 1rem;
  padding-bottom: calc(5rem + env(safe-area-inset-bottom, 0px));
}

/* Card System */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  margin-bottom: 1.25rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

.banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  background-color: var(--status-amber-bg);
  border: 1px solid var(--status-amber-border);
  border-radius: var(--radius-md);
  padding: 0.85rem 1rem;
  margin-bottom: 1.25rem;
}

.banner-text {
  font-size: var(--font-size-sm);
  color: var(--text-primary);
}

/* Button System — Minimum 44px height for Touch Target compliance */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--touch-min);
  padding: 0.5rem 1.25rem;
  font-size: var(--font-size-base);
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease;
  user-select: none;
  touch-action: manipulation;
}

.btn-sm {
  min-height: 36px;
  padding: 0.35rem 0.75rem;
  font-size: var(--font-size-sm);
}

.btn-block {
  width: 100%;
}

.btn-primary {
  background-color: var(--accent-primary);
  color: var(--text-inverse);
}
.btn-primary:hover { background-color: var(--accent-hover); }

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

.btn-danger {
  background-color: var(--status-red);
  color: #ffffff;
}

/* Dashboard View */
.dashboard-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.streak-badge {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  background-color: var(--status-amber-bg);
  border: 1px solid var(--status-amber-border);
  color: var(--status-amber);
  font-weight: 700;
  font-size: var(--font-size-sm);
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-full);
}

.subject-cards-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.subject-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
  cursor: pointer;
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.subject-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.subject-card[data-status="green"] { border-left: 6px solid var(--status-green); }
.subject-card[data-status="amber"] { border-left: 6px solid var(--status-amber); }
.subject-card[data-status="red"] { border-left: 6px solid var(--status-red); }
.subject-card[data-status="grey"] { border-left: 6px solid var(--status-grey); }

.subject-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.subject-name {
  font-weight: 700;
  font-size: var(--font-size-lg);
}

.status-tag {
  font-size: var(--font-size-sm);
  font-weight: 700;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-full);
}
.status-tag.green { background-color: var(--status-green-bg); color: var(--status-green); border: 1px solid var(--status-green-border); }
.status-tag.amber { background-color: var(--status-amber-bg); color: var(--status-amber); border: 1px solid var(--status-amber-border); }
.status-tag.red { background-color: var(--status-red-bg); color: var(--status-red); border: 1px solid var(--status-red-border); }
.status-tag.grey { background-color: var(--status-grey-bg); color: var(--status-grey); border: 1px solid var(--status-grey-border); }

.subject-card-body {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.progress-ring-wrapper {
  position: relative;
  width: 60px;
  height: 60px;
  flex-shrink: 0;
}

.progress-ring-bg { stroke: var(--stage-none); }
.progress-ring-circle {
  stroke: var(--accent-primary);
  transform: rotate(-90deg);
  transform-origin: 50% 50%;
  transition: stroke-dashoffset 0.35s ease;
}

.progress-ring-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-weight: 700;
  font-size: var(--font-size-sm);
}

.pace-info {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.subject-advice {
  margin-top: 0.75rem;
  font-size: var(--font-size-sm);
  color: var(--status-red);
  background-color: var(--status-red-bg);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
}

/* Today's Focus */
.todays-focus {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
}

.focus-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: 0.75rem;
}

.focus-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem;
  border-radius: var(--radius-md);
  background-color: var(--bg-elevated);
  min-height: var(--touch-min);
}

.focus-item-info {
  display: flex;
  flex-direction: column;
}

.focus-item-sub {
  font-size: var(--font-size-sm);
  color: var(--accent-primary);
  font-weight: 700;
}

.focus-item-ch {
  font-size: var(--font-size-base);
  font-weight: 600;
}

.focus-item-stage {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

/* Chapters Screen */
.filter-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
  overflow-x: auto;
  padding-bottom: 0.25rem;
}

.filter-btn {
  min-height: 36px;
  padding: 0.35rem 0.85rem;
  font-size: var(--font-size-sm);
  font-weight: 600;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-color);
  background-color: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  white-space: nowrap;
}
.filter-btn.active {
  background-color: var(--accent-primary);
  color: var(--text-inverse);
  border-color: var(--accent-primary);
}

.group-header {
  font-weight: 700;
  font-size: var(--font-size-sm);
  color: var(--accent-primary);
  margin-top: 1rem;
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.chapter-row {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-bottom: 0.6rem;
  overflow: hidden;
}

.chapter-row.out-of-syllabus {
  opacity: 0.65;
  background-color: var(--bg-elevated);
}

.tag-out-of-syllabus {
  display: inline-block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-muted);
  background-color: var(--border-color);
  padding: 0.15rem 0.45rem;
  border-radius: var(--radius-sm);
  margin-left: 0.5rem;
}

.chapter-row-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1rem;
  min-height: var(--touch-min);
}

.chapter-name-btn {
  background: none;
  border: none;
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex: 1;
  min-height: 44px;
}

.chapter-stage-dots {
  display: flex;
  gap: 0.35rem;
  align-items: center;
}

.stage-dot {
  width: 24px;
  height: 24px;
  min-width: 24px;
  min-height: 24px;
  border-radius: var(--radius-full);
  border: 2px solid var(--border-color);
  background-color: var(--stage-none);
  cursor: pointer;
  transition: transform 0.1s ease, background-color 0.15s ease;
  touch-action: manipulation;
}
.stage-dot:hover { transform: scale(1.15); }
.stage-dot[data-state="progress"] { background-color: var(--stage-progress); border-color: #d97706; }
.stage-dot[data-state="done"] { background-color: var(--stage-done); border-color: #059669; }
.stage-dot.disabled { opacity: 0.35; cursor: not-allowed; }

.chapter-detail-panel {
  display: none;
  padding: 1rem;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-elevated);
}
.chapter-detail-panel.open { display: block; }

.stage-buttons-grid {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  margin-top: 0.75rem;
}

.stage-button-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  min-height: var(--touch-min);
  cursor: pointer;
}

.stage-button-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
}

/* Insights Module Styles */
.insights-top-card {
  margin-bottom: 1.5rem;
}

.trend-chart-wrapper {
  width: 100%;
  overflow-x: auto;
  padding: 0.5rem 0;
}

.insights-svg {
  width: 100%;
  height: auto;
  max-height: 140px;
}

.insights-subject-card {
  margin-bottom: 1.5rem;
}

.donut-chart-wrapper {
  width: 110px;
  height: 110px;
  flex-shrink: 0;
  margin: 0 auto;
}

.donut-svg {
  width: 100%;
  height: 100%;
}

.donut-bg { stroke: var(--stage-none); }
.donut-fill {
  stroke: var(--accent-primary);
  transform: rotate(-90deg);
  transform-origin: 50% 50%;
  transition: stroke-dashoffset 0.4s ease;
}

.pace-comparison-box {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 0.85rem;
  margin-top: 1rem;
}

.pace-bar-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.pace-bar-label {
  font-size: var(--font-size-sm);
  font-weight: 600;
  width: 140px;
  flex-shrink: 0;
}

.pace-bar-track {
  flex: 1;
  height: 14px;
  background-color: var(--stage-none);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.pace-bar-fill {
  height: 100%;
  border-radius: var(--radius-full);
  transition: width 0.3s ease;
}

.pace-bar-fill.green { background-color: var(--status-green); }
.pace-bar-fill.amber { background-color: var(--status-amber); }
.pace-bar-fill.red { background-color: var(--status-red); }
.pace-bar-fill.target { background-color: var(--accent-primary); opacity: 0.8; }

.pace-comparison-subtext {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-top: 0.5rem;
}

.stage-breakdown-container {
  margin-top: 1rem;
}

.stage-breakdown-row {
  margin-bottom: 0.75rem;
}

.stage-breakdown-header {
  display: flex;
  justify-content: space-between;
  font-size: var(--font-size-sm);
  margin-bottom: 0.25rem;
}

.stage-breakdown-header .stage-name { font-weight: 600; }
.stage-breakdown-header .stage-counts { color: var(--text-muted); font-size: var(--font-size-sm); }

.stacked-bar {
  display: flex;
  height: 14px;
  width: 100%;
  border-radius: var(--radius-full);
  overflow: hidden;
  background-color: var(--stage-none);
}

.bar-segment.done { background-color: var(--status-green); }
.bar-segment.progress { background-color: var(--status-amber); }
.bar-segment.none { background-color: var(--stage-none); }

.focus-callout {
  margin-top: 1rem;
  background-color: var(--status-amber-bg);
  border: 1px solid var(--status-amber-border);
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  padding: 0.75rem;
  border-radius: var(--radius-md);
}

/* Bottom Navigation Bar */
.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background-color: var(--bg-card);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-around;
  align-items: center;
  padding: 0.4rem 0;
  padding-bottom: calc(0.4rem + env(safe-area-inset-bottom, 0px));
  padding-left: env(safe-area-inset-left, 0px);
  padding-right: env(safe-area-inset-right, 0px);
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1;
  min-height: var(--touch-min);
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  touch-action: manipulation;
}

.nav-item svg {
  width: 22px;
  height: 22px;
  fill: currentColor;
  margin-bottom: 2px;
}

.nav-item.active {
  color: var(--accent-primary);
}

/* Modal Overlay */
.modal-overlay {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 200;
  background-color: rgba(0, 0, 0, 0.6);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.modal-overlay.open {
  display: flex;
}

.modal-content {
  background-color: var(--bg-card);
  border-radius: var(--radius-lg);
  max-width: 500px;
  width: 100%;
  max-height: 90vh;
  max-height: 90dvh;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  margin-top: env(safe-area-inset-top, 0px);
  margin-bottom: env(safe-area-inset-bottom, 0px);
}

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

.modal-body {
  padding: 1rem;
  overflow-y: auto;
  flex: 1;
}

.pdf-embed-wrapper {
  width: 100%;
  height: 70vh;
  height: 70dvh;
}

.pdf-embed-wrapper embed,
.pdf-embed-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
}

/* Custom Confirmation & Diagnostic Modals */
.modal-danger-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background-color: var(--status-red-bg);
  color: var(--status-red);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin: 0 auto 0.75rem auto;
}

.confirm-input-instruction {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
}

.confirm-error-msg {
  color: var(--status-red);
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-top: 0.4rem;
  display: none;
}

.confirm-error-msg.visible {
  display: block;
}

.modal-footer-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: flex-end;
  margin-top: 1.25rem;
}

@media (max-width: 480px) {
  .modal-footer-actions {
    flex-direction: column-reverse;
  }
  .modal-footer-actions .btn {
    width: 100%;
  }
}

/* Onboarding & Syllabus Checklist */
.onboarding-card {
  max-width: 550px;
  margin: 1.5rem auto;
}

.onboarding-step {
  display: none;
}

.onboarding-step.active {
  display: block;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text-primary);
}

.form-input {
  width: 100%;
  min-height: var(--touch-min);
  padding: 0.6rem 0.8rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background-color: var(--bg-input);
  color: var(--text-primary);
  font-size: var(--font-size-base);
  font-family: inherit;
}

.form-input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.syllabus-checkbox-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.75rem 0.5rem;
  border-bottom: 1px solid var(--border-color);
  cursor: pointer;
  min-height: var(--touch-min);
}

.syllabus-checkbox-item input[type="checkbox"] {
  width: 22px;
  height: 22px;
  accent-color: var(--accent-primary);
  cursor: pointer;
}

.backfill-chapter-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--border-color);
  min-height: var(--touch-min);
}

/* Footer Styling */
.app-footer {
  text-align: center;
  padding: 1.5rem 1rem;
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-card);
  margin-top: auto;
}

/* Helper Utilities */
.hidden { display: none !important; }
.text-center { text-align: center; }
.text-bold { font-weight: 700; }
.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mb-4 { margin-bottom: 1rem; }

/* ==========================================
   RESPONSIVE BREAKPOINTS (CSS Media Queries)
   ========================================== */

/* Tablet Breakpoint (600px - 1024px) */
@media (min-width: 600px) {
  .subject-cards-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .stage-buttons-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }
}

/* Desktop Breakpoint (> 1024px) */
@media (min-width: 1024px) {
  .subject-cards-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .app-main {
    padding-bottom: 3rem;
  }
}

.pyq-external-box {
  margin-top: 1rem;
  padding: 0.75rem;
  border-radius: 8px;
  background: var(--surface-secondary);
  border: 1px solid var(--border-color);
}

.pyq-external-box .pyq-title {
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--text-primary);
}

.pyq-external-box .pyq-note {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
  margin: 0 0 0.5rem 0;
}