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

:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fee2e2;
  --warning: #f59e0b;
  --warning-bg: #fef3c7;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-500: #6b7280;
  --gray-700: #374151;
  --gray-900: #111827;
  --radius: 10px;
}

body {
  font-family: "Hiragino Kaku Gothic Pro", "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--gray-50);
  color: var(--gray-900);
  line-height: 1.6;
  min-height: 100vh;
}

#app {
  max-width: 800px;
  margin: 0 auto;
  padding: 16px;
}

header {
  text-align: center;
  margin-bottom: 24px;
}

header h1 {
  font-size: 1.8rem;
  color: var(--primary);
  margin-bottom: 16px;
}

#main-nav {
  display: flex;
  gap: 4px;
  background: var(--gray-200);
  padding: 4px;
  border-radius: var(--radius);
}

.nav-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  background: transparent;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  color: var(--gray-500);
}

.nav-btn.active {
  background: white;
  color: var(--primary);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.nav-btn:hover:not(.active) {
  color: var(--gray-700);
}

.mode-section {
  display: none;
}

.mode-section.active {
  display: block;
}

.btn-primary {
  background: var(--primary);
  color: white;
  border: none;
  padding: 10px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-primary:hover {
  background: var(--primary-hover);
}

.btn-secondary {
  background: white;
  color: var(--gray-700);
  border: 1px solid var(--gray-300);
  padding: 8px 16px;
  border-radius: 8px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-secondary:hover {
  background: var(--gray-100);
}

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

.btn-danger {
  background: var(--danger);
  color: white;
  border: none;
  padding: 10px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
}

.btn-danger:hover {
  background: #b91c1c;
}

/* Study Mode */
.study-header {
  text-align: center;
  margin-bottom: 20px;
}

.study-header h2 {
  font-size: 1.3rem;
  margin-bottom: 4px;
}

.study-header p {
  color: var(--gray-500);
  font-size: 0.9rem;
  margin-bottom: 12px;
}

.day-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
}

#day-counter {
  font-weight: 600;
  color: var(--gray-500);
  font-size: 0.9rem;
}

#study-progress-bar {
  height: 6px;
  background: var(--gray-200);
  border-radius: 3px;
  margin-bottom: 20px;
  overflow: hidden;
}

#study-progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 3px;
  transition: width 0.3s;
  width: 0%;
}

#study-section-label {
  font-size: 0.85rem;
  color: var(--gray-500);
  margin-bottom: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* Study Cards */
.study-card {
  background: white;
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  border-left: 4px solid var(--primary);
}

.study-card.review-card {
  border-left-color: var(--warning);
}

.study-card .section-tag {
  font-size: 0.75rem;
  color: var(--gray-500);
  margin-bottom: 8px;
  font-weight: 600;
  text-transform: uppercase;
}

.study-card .full-text {
  font-size: 1.1rem;
  line-height: 1.8;
  margin-bottom: 12px;
}

.study-card .full-text .blank-word {
  color: var(--danger);
  font-weight: 700;
  border-bottom: 2px solid var(--danger);
  padding-bottom: 1px;
}

.study-card .write-practice {
  margin-top: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.study-card .write-practice .blank-input-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.study-card .write-practice .blank-input-row label {
  font-size: 0.85rem;
  color: var(--gray-500);
  min-width: 24px;
  font-weight: 600;
}

.study-card .write-practice .blank-input-row input {
  flex: 1;
  padding: 8px 12px;
  border: 2px solid var(--gray-200);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
}

.study-card .write-practice .blank-input-row input:focus {
  outline: none;
  border-color: var(--primary);
}

.study-card .write-practice .blank-input-row input.correct {
  border-color: var(--success);
  background: var(--success-bg);
}

.study-card .write-practice .blank-input-row input.wrong {
  border-color: var(--danger);
  background: var(--danger-bg);
}

.study-card .submit-answer-btn {
  background: var(--primary);
  color: white;
  border: none;
  padding: 10px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  width: 100%;
}

.study-card .submit-answer-btn:hover {
  background: var(--primary-hover);
}

.check-btn {
  margin-top: 8px;
  background: var(--primary);
  color: white;
  border: none;
  padding: 6px 16px;
  border-radius: 6px;
  font-size: 0.85rem;
  cursor: pointer;
}

.check-btn:hover {
  background: var(--primary-hover);
}

.card-toggle {
  display: flex;
  gap: 8px;
  margin-bottom: 12px;
}

.card-toggle button {
  padding: 4px 12px;
  border: 1px solid var(--gray-300);
  background: white;
  border-radius: 6px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.2s;
}

.card-toggle button.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.hidden-blanks .blank-word {
  background: transparent !important;
  color: transparent !important;
  border-radius: 3px;
  padding: 0 4px;
  cursor: pointer;
  user-select: none;
  transition: all 0.2s;
  border-bottom: 2px solid var(--danger) !important;
}

.hidden-blanks .blank-word.revealed {
  background: transparent !important;
  color: var(--danger) !important;
  border-bottom: 2px solid var(--danger) !important;
}

/* Practice Mode */
.practice-header {
  text-align: center;
  margin-bottom: 24px;
}

.practice-header h2 {
  margin-bottom: 16px;
}

.practice-filters {
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: flex-start;
}


.practice-filters select {
  padding: 8px 12px;
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  font-size: 0.9rem;
  font-family: inherit;
}

.section-select-all {
  text-align: left;
  width: 100%;
  margin: 0 0 8px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--gray-200);
}

.section-select-all .section-checkbox-label {
  font-weight: 700;
}

.section-checkboxes {
  display: flex;
  flex-direction: column;
  gap: 6px;
  text-align: left;
  width: 100%;
  margin: 0 0 16px;
}

.section-checkbox-label {
  display: flex;
  flex-direction: row;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--gray-700);
  cursor: pointer;
  padding: 6px 10px;
  border-radius: 6px;
  transition: background 0.15s;
  white-space: nowrap;
}

.section-checkbox-label:hover {
  background: var(--gray-100);
}

.section-checkbox-label input {
  width: 16px;
  height: 16px;
  cursor: pointer;
}

#practice-input-toggle {
  display: flex;
  gap: 4px;
  background: var(--gray-200);
  padding: 3px;
  border-radius: 8px;
  margin-bottom: 16px;
  width: fit-content;
}

#practice-input-toggle .nav-btn {
  padding: 6px 16px;
  font-size: 0.85rem;
}

#practice-progress {
  display: flex;
  justify-content: space-between;
  margin-bottom: 16px;
  font-weight: 600;
  color: var(--gray-500);
}

#practice-card {
  background: white;
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  margin-bottom: 16px;
}

#practice-card .question-section {
  font-size: 0.8rem;
  color: var(--gray-500);
  margin-bottom: 8px;
  font-weight: 600;
}

#practice-card .question-text {
  font-size: 1.15rem;
  line-height: 1.8;
}

#practice-card .question-text .blank-slot {
  display: inline-block;
  min-width: 80px;
  border-bottom: 2px solid var(--primary);
  padding: 2px 4px;
  margin: 0 2px;
  text-align: center;
  font-weight: 600;
}

#practice-card .question-text .blank-slot.filled {
  color: var(--primary);
}

#practice-card .question-text .blank-slot.correct-slot {
  color: var(--success);
  border-color: var(--success);
}

#practice-card .question-text .blank-slot.wrong-slot {
  color: var(--danger);
  border-color: var(--danger);
}

#practice-input-area {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

#practice-input-area .blank-input-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

#practice-input-area .blank-input-row label {
  font-size: 0.85rem;
  color: var(--gray-500);
  min-width: 24px;
  font-weight: 600;
}

#practice-input-area .blank-input-row input {
  flex: 1;
  padding: 8px 12px;
  border: 2px solid var(--gray-200);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
}

#practice-input-area .blank-input-row input:focus {
  outline: none;
  border-color: var(--primary);
}

#practice-input-area .blank-input-row input.correct {
  border-color: var(--success);
  background: var(--success-bg);
}

#practice-input-area .blank-input-row input.wrong {
  border-color: var(--danger);
  background: var(--danger-bg);
}

.submit-answer-btn {
  background: var(--primary);
  color: white;
  border: none;
  padding: 10px 24px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  width: 100%;
}

.submit-answer-btn:hover {
  background: var(--primary-hover);
}

#practice-feedback {
  padding: 12px 16px;
  border-radius: 8px;
  margin-bottom: 16px;
  display: none;
  font-weight: 600;
}

#practice-feedback.success {
  display: block;
  background: var(--success-bg);
  color: var(--success);
}

#practice-feedback.error {
  display: block;
  background: var(--danger-bg);
  color: var(--danger);
}

#practice-feedback .correct-answer {
  margin-top: 8px;
  font-weight: 400;
  font-size: 0.9rem;
}

/* Practice Results */
#practice-results, #mock-results {
  text-align: center;
}

#results-summary, #mock-results-summary {
  background: white;
  border-radius: var(--radius);
  padding: 24px;
  margin: 16px 0;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

.score-big {
  font-size: 3rem;
  font-weight: 800;
  color: var(--primary);
}

.score-big.pass {
  color: var(--success);
}

.score-big.fail {
  color: var(--danger);
}

.score-label {
  font-size: 1rem;
  color: var(--gray-500);
  margin-top: 4px;
}

#results-details, #mock-results-details {
  text-align: left;
  margin: 16px 0;
}

.result-item {
  background: white;
  border-radius: 8px;
  padding: 12px 16px;
  margin-bottom: 8px;
  border-left: 4px solid var(--success);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.result-item.wrong {
  border-left-color: var(--danger);
}

.result-item .result-question {
  font-size: 0.95rem;
  margin-bottom: 4px;
}

.result-item .result-answer {
  font-size: 0.85rem;
  color: var(--gray-500);
}

.result-item .result-answer strong {
  color: var(--danger);
}

/* Mock Test */
.mock-header {
  text-align: center;
  margin-bottom: 24px;
}

.mock-header h2 {
  margin-bottom: 8px;
}

.mock-header p {
  color: var(--gray-500);
  margin-bottom: 16px;
}

#mock-timer {
  text-align: center;
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--gray-700);
  margin-bottom: 8px;
}

#mock-progress {
  text-align: center;
  color: var(--gray-500);
  font-weight: 600;
  margin-bottom: 16px;
}

#mock-card {
  background: white;
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  margin-bottom: 16px;
}

#mock-card .question-number {
  font-size: 0.85rem;
  color: var(--primary);
  font-weight: 700;
  margin-bottom: 8px;
}

#mock-card .question-section {
  font-size: 0.8rem;
  color: var(--gray-500);
  margin-bottom: 8px;
}

#mock-card .question-text {
  font-size: 1.1rem;
  line-height: 1.8;
}

#mock-card .question-text .blank-slot {
  display: inline-block;
  min-width: 80px;
  border-bottom: 2px solid var(--primary);
  padding: 2px 4px;
  margin: 0 2px;
  text-align: center;
  font-weight: 600;
  color: var(--primary);
}

#mock-input-area {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

#mock-input-area .blank-input-row {
  display: flex;
  align-items: center;
  gap: 8px;
}

#mock-input-area .blank-input-row label {
  font-size: 0.85rem;
  color: var(--gray-500);
  min-width: 24px;
  font-weight: 600;
}

#mock-input-area .blank-input-row input {
  flex: 1;
  padding: 8px 12px;
  border: 2px solid var(--gray-200);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
}

#mock-input-area .blank-input-row input:focus {
  outline: none;
  border-color: var(--primary);
}

#mock-nav {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 16px;
}

#mock-question-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 4px;
  margin-bottom: 16px;
}

.grid-btn {
  padding: 8px 4px;
  border: 1px solid var(--gray-300);
  background: white;
  border-radius: 6px;
  font-size: 0.8rem;
  cursor: pointer;
  text-align: center;
  font-weight: 600;
}

.grid-btn.current {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.grid-btn.answered {
  background: #dbeafe;
  border-color: var(--primary);
  color: var(--primary);
}

.grid-btn.correct-grid {
  background: var(--success-bg);
  border-color: var(--success);
  color: var(--success);
}

.grid-btn.wrong-grid {
  background: var(--danger-bg);
  border-color: var(--danger);
  color: var(--danger);
}

#mock-finish {
  display: block;
  margin: 0 auto;
}

/* Review Section */
#study-review-section h3 {
  color: var(--warning);
  font-size: 1rem;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--warning-bg);
}

footer {
  text-align: center;
  padding: 24px 0;
  color: var(--gray-500);
  font-size: 0.85rem;
}

@media (max-width: 600px) {
  #app {
    padding: 12px;
  }

  header h1 {
    font-size: 1.4rem;
  }

  .nav-btn {
    padding: 8px 8px;
    font-size: 0.85rem;
  }

  .practice-filters {
    flex-direction: column;
    align-items: stretch;
  }

  #mock-question-grid {
    grid-template-columns: repeat(6, 1fr);
  }

  .day-nav {
    flex-wrap: wrap;
  }

  #mock-nav {
    flex-wrap: wrap;
  }

  .hw-canvas {
    width: 100% !important;
    height: 120px !important;
  }
}

/* Question Reference (shown in handwrite/type modes) */
.question-reference {
  background: white;
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  font-size: 1.1rem;
  line-height: 1.8;
}

.question-reference .question-text .blank-slot {
  display: inline-block;
  min-width: 80px;
  border-bottom: 2px solid var(--primary);
  padding: 2px 4px;
  margin: 0 2px;
  text-align: center;
  font-weight: 600;
  color: var(--primary);
  font-size: 0.85rem;
}

/* Handwriting Canvas */
.hw-canvas-container {
  margin-top: 12px;
}

.hw-canvas {
  display: block;
  width: 100%;
  height: 150px;
  border: 2px solid var(--gray-200);
  border-radius: 8px;
  background: white;
  cursor: crosshair;
  touch-action: none;
}

.hw-canvas:active {
  border-color: var(--primary);
}

.hw-toolbar {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.hw-btn {
  padding: 5px 14px;
  border: 1px solid var(--gray-300);
  background: white;
  border-radius: 6px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s;
}

.hw-btn:hover {
  background: var(--gray-100);
}

.hw-answer-reveal {
  margin-top: 12px;
  padding: 10px 14px;
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: 8px;
}

.hw-answer-reveal .hw-answer-label {
  font-size: 0.8rem;
  color: var(--gray-500);
  font-weight: 600;
  margin-bottom: 4px;
}

.hw-answer-reveal .hw-answer-text {
  font-size: 1.1rem;
  color: var(--danger);
  font-weight: 700;
}

.hw-blank-item {
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--gray-100);
}

.hw-blank-item:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}

.hw-blank-label {
  font-size: 0.85rem;
  color: var(--gray-500);
  font-weight: 600;
  margin-bottom: 6px;
}

.hw-self-check {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.hw-self-check button {
  padding: 5px 14px;
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
}

.hw-self-check .hw-correct-btn {
  background: var(--success-bg);
  color: var(--success);
}

.hw-self-check .hw-wrong-btn {
  background: var(--danger-bg);
  color: var(--danger);
}