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

:root {
  --bg: #0f1419;
  --surface: #1a2332;
  --surface-2: #243044;
  --text: #e8edf4;
  --text-muted: #8b9cb3;
  --accent: #ff6b4a;
  --accent-2: #4dabf7;
  --success: #51cf66;
  --danger: #ff4757;
  --radius: 14px;
  --font-mono: "Cascadia Code", "SF Mono", Consolas, monospace;
}

html,
body {
  height: 100%;
}

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
}

.app {
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 20px 48px;
}

/* Header & Pagination */
.header {
  text-align: center;
  margin-bottom: 32px;
}

.header h1 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-bottom: 20px;
  color: var(--text);
}

.pagination {
  display: inline-flex;
  gap: 8px;
  background: var(--surface);
  padding: 6px;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.06);
}

.page-btn {
  padding: 10px 18px;
  border: none;
  border-radius: 8px;
  background: transparent;
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
  white-space: nowrap;
}

.page-btn:hover {
  color: var(--text);
  background: var(--surface-2);
}

.page-btn.active {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 14px rgba(255, 107, 74, 0.35);
}

/* Task pages */
.task-page {
  display: none;
  position: relative;
  background: var(--surface);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.06);
  padding: 28px 24px 32px;
  min-height: 480px;
}

.task-page.active {
  display: block;
}

.task-header {
  text-align: center;
  margin-bottom: 28px;
}

.task-header h2 {
  font-size: 1.25rem;
  margin-bottom: 8px;
}

.task-desc {
  font-size: 0.875rem;
  color: var(--text-muted);
  max-width: 520px;
  margin: 0 auto;
}

.task-desc kbd {
  display: inline-block;
  padding: 2px 7px;
  background: var(--surface-2);
  border-radius: 5px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

/* Task 1 */
.task1-body,
.task2-body {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.number-display {
  font-family: var(--font-mono);
  font-size: 4.5rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--accent);
  text-shadow: 0 0 40px rgba(255, 107, 74, 0.25);
  line-height: 1;
  user-select: none;
}

/* Timer bar */
.timer-bar-wrap {
  width: 100%;
  max-width: 400px;
  height: 10px;
  background: var(--surface-2);
  border-radius: 999px;
  overflow: hidden;
}

.timer-bar {
  height: 100%;
  width: 100%;
  background: linear-gradient(90deg, var(--accent), #ff9f7a);
  border-radius: 999px;
  transform-origin: left center;
  transition: none;
}

.timer-bar--blue {
  background: linear-gradient(90deg, var(--accent-2), #74c0fc);
}

.timer-bar.urgent {
  background: linear-gradient(90deg, var(--danger), #ff6b81);
}

.timer-label {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: -12px;
}

/* Input */
.input-row {
  display: flex;
  gap: 10px;
  width: 100%;
  max-width: 400px;
}

.answer-input {
  flex: 1;
  padding: 14px 18px;
  font-size: 1.25rem;
  font-family: var(--font-mono);
  background: var(--surface-2);
  border: 2px solid rgba(255, 255, 255, 0.08);
  border-radius: 10px;
  color: var(--text);
  outline: none;
  transition: border-color 0.2s;
}

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

.answer-input:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.confirm-btn {
  padding: 14px 22px;
  font-size: 1rem;
  font-weight: 600;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: opacity 0.2s, transform 0.1s;
}

.confirm-btn:hover:not(:disabled) {
  opacity: 0.9;
}

.confirm-btn:active:not(:disabled) {
  transform: scale(0.97);
}

.confirm-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

/* Task 2 */
.history-row {
  width: 100%;
  text-align: center;
}

.history-label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}

.history-queue {
  display: flex;
  justify-content: center;
  gap: 10px;
}

.history-slot {
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--surface-2);
  border-radius: 10px;
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 600;
  border: 2px solid rgba(255, 255, 255, 0.06);
  transition: border-color 0.2s, background 0.2s;
}

.history-slot.current {
  border-color: var(--accent-2);
  background: rgba(77, 171, 247, 0.12);
}

.history-slot.empty {
  color: var(--text-muted);
  font-weight: 400;
}

.dual-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  width: 100%;
}

.stimulus-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 32px 16px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.06);
  min-height: 160px;
}

.card-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 12px;
}

.card-value {
  font-family: var(--font-mono);
  font-size: 4rem;
  font-weight: 700;
  line-height: 1;
}

.letter-card .card-value {
  color: var(--accent-2);
}

.digit-card .card-value {
  color: #ffd43b;
}

/* Task 3 */
.task3-body {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.task3-instruction {
  font-size: 1rem;
  line-height: 1.6;
  text-align: center;
  color: var(--text);
  max-width: 480px;
}

.task3-image-wrap {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
}

.task3-image {
  display: block;
  max-width: 100%;
  max-height: 360px;
  width: auto;
  height: auto;
  border-radius: 12px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
  object-fit: contain;
}

.timer-bar--amber {
  background: linear-gradient(90deg, #ffd43b, #ff922b);
}

.overlay-text--done {
  margin-top: 0;
  font-size: 1.75rem;
  color: var(--text);
}

.hint-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

.hint-tag {
  font-size: 0.8rem;
  padding: 6px 12px;
  background: var(--surface-2);
  border-radius: 8px;
  color: var(--text-muted);
}

.hint-tag.active {
  color: var(--success);
  background: rgba(81, 207, 102, 0.12);
}

/* Stats */
.stats-row {
  display: flex;
  gap: 24px;
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 8px;
}

.stats-row strong {
  color: var(--text);
  font-weight: 600;
}

/* Session timer (2-minute task duration) */
.session-row {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  max-width: 400px;
}

.session-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.session-bar-wrap {
  flex: 1;
  height: 6px;
  background: var(--surface-2);
  border-radius: 999px;
  overflow: hidden;
}

.session-bar {
  height: 100%;
  width: 100%;
  background: linear-gradient(90deg, #51cf66, #94d82d);
  border-radius: 999px;
  transform-origin: left center;
}

.session-bar--blue {
  background: linear-gradient(90deg, var(--accent-2), #74c0fc);
}

.session-bar.urgent {
  background: linear-gradient(90deg, var(--danger), #ff6b81);
}

.session-time {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-muted);
  min-width: 3.2em;
  text-align: right;
}

/* Summary overlay */
.summary-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 20, 25, 0.9);
  border-radius: var(--radius);
  z-index: 15;
}

.summary-overlay.hidden {
  display: none;
}

.summary-card {
  text-align: center;
  padding: 32px 36px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border: 1px solid rgba(255, 255, 255, 0.08);
  min-width: 260px;
}

.summary-card h3 {
  font-size: 1.25rem;
  margin-bottom: 20px;
}

.summary-stat {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.summary-stat strong {
  color: var(--text);
  font-size: 1.25rem;
}

.summary-card .confirm-btn {
  margin-top: 20px;
  width: 100%;
}

/* Start panel */
.start-panel {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 20, 25, 0.75);
  border-radius: var(--radius);
  z-index: 5;
}

.start-panel.hidden {
  display: none;
}

.start-btn {
  padding: 16px 48px;
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  background: linear-gradient(135deg, var(--accent), #ff8f6b);
  color: #fff;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: 0 6px 24px rgba(255, 107, 74, 0.4);
  transition: transform 0.15s, box-shadow 0.15s;
}

.start-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(255, 107, 74, 0.5);
}

.start-btn:active {
  transform: translateY(0);
}

/* Start panel */
.start-panel {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(15, 20, 25, 0.72);
  border-radius: var(--radius);
  z-index: 5;
}

.start-panel.hidden {
  display: none;
}

.start-btn {
  padding: 16px 48px;
  font-size: 1.125rem;
  font-weight: 600;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(255, 107, 74, 0.35);
  transition: opacity 0.2s, transform 0.1s;
}

.start-btn:hover {
  opacity: 0.92;
}

.start-btn:active {
  transform: scale(0.97);
}

/* Overlay */
.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: rgba(15, 20, 25, 0.88);
  border-radius: var(--radius);
  z-index: 10;
  animation: overlay-in 0.25s ease;
}

.overlay.hidden {
  display: none;
}

@keyframes overlay-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.red-cross {
  font-size: 8rem;
  font-weight: 900;
  color: var(--danger);
  line-height: 1;
  text-shadow: 0 0 60px rgba(255, 71, 87, 0.6);
  animation: cross-pulse 0.6s ease infinite alternate;
  user-select: none;
}

@keyframes cross-pulse {
  from {
    transform: scale(1);
    opacity: 0.9;
  }
  to {
    transform: scale(1.06);
    opacity: 1;
  }
}

.overlay-text {
  margin-top: 16px;
  font-size: 1.1rem;
  color: var(--danger);
  font-weight: 600;
}

@media (max-width: 480px) {
  .number-display {
    font-size: 3.2rem;
  }

  .card-value {
    font-size: 3rem;
  }

  .page-btn {
    padding: 8px 12px;
    font-size: 0.8rem;
  }

  .dual-cards {
    gap: 10px;
  }

  .stimulus-card {
    padding: 24px 12px;
    min-height: 130px;
  }

  .task3-image {
    max-height: 260px;
  }

  .task3-instruction {
    font-size: 0.9rem;
  }
}