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

:root {
  --primary-color: #2c3e50;
  --secondary-color: #3498db;
  --accent-color: #e74c3c;
  --success-color: #27ae60;
  --warning-color: #f39c12;
  --bg-color: #f5f6fa;
  --card-bg: #ffffff;
  --text-color: #2c3e50;
  --text-light: #7f8c8d;
  --border-color: #dcdde1;
  --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  --addition-color: #27ae60;
  --subtraction-color: #e74c3c;
}

body {
  font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  min-height: 100vh;
}

/* 헤더 */
.header {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
  padding: 1.5rem;
  text-align: center;
  box-shadow: var(--shadow);
}

.header h1 {
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
}

.header p {
  opacity: 0.9;
  font-size: 0.95rem;
}

/* 네비게이션 */
.nav {
  display: flex;
  justify-content: center;
  gap: 1rem;
  padding: 1rem;
  background: var(--card-bg);
  border-bottom: 1px solid var(--border-color);
}

.nav a {
  text-decoration: none;
  color: var(--text-color);
  padding: 0.5rem 1.5rem;
  border-radius: 25px;
  transition: all 0.3s ease;
  font-weight: 500;
  cursor: pointer;
}

.nav a:hover,
.nav a.active {
  background: var(--secondary-color);
  color: white;
}

/* 컨테이너 */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* 단계 선택 그리드 */
.level-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

@media (max-width: 600px) {
  .level-grid {
    grid-template-columns: 1fr;
  }
}

.level-column {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  background: var(--card-bg);
  border-radius: 16px;
  padding: 1rem;
  box-shadow: var(--shadow);
}

.level-column.addition-block {
  border: 3px solid #27ae60;
}

.level-column.subtraction-block {
  border: 3px solid #e74c3c;
}

.column-title {
  font-size: 1.3rem;
  font-weight: 700;
  padding: 0.75rem;
  border-radius: 10px;
  text-align: center;
  color: white;
  margin-bottom: 0.5rem;
}

.column-title.addition {
  background: linear-gradient(135deg, #27ae60, #2ecc71);
}

.column-title.subtraction {
  background: linear-gradient(135deg, #e74c3c, #c0392b);
}

.level-card {
  background: var(--bg-color);
  border-radius: 10px;
  padding: 1rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  cursor: pointer;
  transition: all 0.3s ease;
  border: 2px solid var(--border-color);
}

.level-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.addition-block .level-card:hover {
  border-color: #27ae60;
  background: #f0fff4;
}

.subtraction-block .level-card:hover {
  border-color: #e74c3c;
  background: #fff5f5;
}

.level-icon {
  width: 50px;
  height: 50px;
  background: linear-gradient(135deg, var(--secondary-color), #2980b9);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
  font-weight: 700;
  flex-shrink: 0;
}

.level-info {
  flex: 1;
}

.level-info h3 {
  font-size: 1.1rem;
  margin-bottom: 0.25rem;
  color: var(--primary-color);
}

.level-info p {
  font-size: 0.9rem;
  color: var(--text-light);
}

.level-best {
  background: var(--bg-color);
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--warning-color);
  text-align: center;
  min-width: 50px;
}

/* 게임 화면 */
.game-container {
  max-width: 600px;
}

.game-header {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 1rem 1.5rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.game-info,
.game-stats {
  display: flex;
  gap: 1.5rem;
}

.game-info span,
.game-stats span {
  font-weight: 500;
}

#timer {
  font-family: 'Courier New', monospace;
  font-size: 1.1rem;
  color: var(--secondary-color);
  font-weight: 700;
}

#correctCount {
  color: var(--success-color);
}

/* 문제 영역 */
.question-area {
  background: var(--card-bg);
  border-radius: 16px;
  padding: 2.5rem;
  box-shadow: var(--shadow);
  text-align: center;
  margin-bottom: 1.5rem;
}

.question {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: 2rem;
  font-family: 'Courier New', monospace;
}

@media (max-width: 480px) {
  .question {
    font-size: 1.8rem;
  }
}

/* 4지선다 선택지 */
.choices {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
  max-width: 400px;
  margin: 0 auto;
}

.choice-btn {
  padding: 1.25rem 1rem;
  font-size: 1.4rem;
  font-weight: 600;
  font-family: 'Courier New', monospace;
  background: white;
  border: 3px solid var(--border-color);
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.choice-btn:hover:not(:disabled) {
  border-color: var(--secondary-color);
  background: #f0f8ff;
  transform: translateY(-2px);
}

.choice-btn:active:not(:disabled) {
  transform: translateY(0);
}

.choice-btn:disabled {
  cursor: not-allowed;
}

.choice-btn.correct {
  border-color: var(--success-color);
  background: #d4edda;
  color: var(--success-color);
}

.choice-btn.wrong {
  border-color: var(--accent-color);
  background: #f8d7da;
  color: var(--accent-color);
}

@media (max-width: 480px) {
  .choices {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
  }

  .choice-btn {
    padding: 1rem 0.75rem;
    font-size: 1.2rem;
  }
}

.feedback {
  margin-top: 1rem;
  font-size: 1.2rem;
  font-weight: 600;
  min-height: 2rem;
}

.feedback.correct {
  color: var(--success-color);
}

.feedback.wrong {
  color: var(--accent-color);
}

/* 게임 버튼 */
.game-buttons {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.btn-submit,
.btn-quit {
  padding: 0.875rem 2rem;
  font-size: 1.1rem;
  font-weight: 600;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s;
}

.btn-submit {
  background: linear-gradient(135deg, var(--secondary-color), #2980b9);
  color: white;
}

.btn-submit:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(52, 152, 219, 0.4);
}

.btn-quit {
  background: var(--border-color);
  color: var(--text-color);
}

.btn-quit:hover {
  background: #bdc3c7;
}

/* 결과 화면 */
.result-container {
  max-width: 500px;
}

.result-card {
  background: var(--card-bg);
  border-radius: 20px;
  padding: 2.5rem;
  box-shadow: var(--shadow);
  text-align: center;
}

.result-card h2 {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.result-level {
  color: var(--text-light);
  font-size: 1.1rem;
  margin-bottom: 2rem;
}

.result-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1.5rem;
}

.stat-item {
  text-align: center;
}

.stat-label {
  display: block;
  color: var(--text-light);
  font-size: 0.9rem;
  margin-bottom: 0.25rem;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

.stat-value.score {
  color: var(--warning-color);
}

/* 이름 입력 영역 */
.name-input-area {
  margin-bottom: 1.5rem;
  text-align: center;
}

.name-input-area label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--text-color);
}

.name-input-area input {
  width: 100%;
  max-width: 200px;
  padding: 0.75rem 1rem;
  font-size: 1.1rem;
  border: 2px solid var(--border-color);
  border-radius: 8px;
  text-align: center;
  margin-bottom: 0.75rem;
}

.name-input-area input:focus {
  outline: none;
  border-color: var(--secondary-color);
}

.btn-save-name {
  padding: 0.75rem 2rem;
  font-size: 1rem;
  font-weight: 600;
  background: linear-gradient(135deg, var(--secondary-color), #2980b9);
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.3s;
}

.btn-save-name:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(52, 152, 219, 0.4);
}

.result-rank {
  background: linear-gradient(135deg, #fff3cd, #ffeaa7);
  padding: 1rem 1.5rem;
  border-radius: 12px;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.rank-badge {
  font-size: 1.5rem;
}

.rank-text {
  font-weight: 600;
  color: #856404;
}

.result-buttons {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

.btn-retry,
.btn-home {
  padding: 0.875rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s;
}

.btn-retry {
  background: linear-gradient(135deg, var(--success-color), #219653);
  color: white;
}

.btn-retry:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(39, 174, 96, 0.4);
}

.btn-home {
  background: var(--border-color);
  color: var(--text-color);
}

.btn-home:hover {
  background: #bdc3c7;
}

/* 통합 랭킹 섹션 */
.ranking-section {
  margin-top: 2rem;
  background: var(--card-bg);
  border-radius: 16px;
  padding: 1.5rem;
  box-shadow: var(--shadow);
}

.ranking-title {
  font-size: 1.3rem;
  color: var(--primary-color);
  margin-bottom: 1rem;
  text-align: center;
}

.ranking-inline .ranking-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.95rem;
}

.ranking-inline .ranking-table th,
.ranking-inline .ranking-table td {
  padding: 0.75rem 0.5rem;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
}

.ranking-inline .ranking-table th {
  background: var(--bg-color);
  color: var(--text-light);
  font-weight: 600;
}

.ranking-inline .ranking-table tbody tr:hover {
  background: #f8f9fa;
}

.ranking-inline .ranking-table tbody tr:first-child td {
  font-weight: 600;
  color: var(--warning-color);
}

.no-ranking {
  text-align: center;
  color: var(--text-light);
  padding: 2rem;
  font-size: 1rem;
}

@media (max-width: 480px) {
  .ranking-inline .ranking-table {
    font-size: 0.85rem;
  }

  .ranking-inline .ranking-table th,
  .ranking-inline .ranking-table td {
    padding: 0.6rem 0.3rem;
  }
}

/* 랭킹 모달 */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  padding: 1rem;
}

.modal-content {
  background: var(--card-bg);
  border-radius: 20px;
  width: 100%;
  max-width: 600px;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  background: var(--card-bg);
  border-radius: 20px 20px 0 0;
}

.modal-header h2 {
  font-size: 1.5rem;
}

.modal-close {
  width: 36px;
  height: 36px;
  border: none;
  background: var(--bg-color);
  border-radius: 50%;
  font-size: 1.5rem;
  cursor: pointer;
  transition: all 0.3s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modal-close:hover {
  background: var(--accent-color);
  color: white;
}

.ranking-tabs {
  display: flex;
  padding: 1rem;
  gap: 0.5rem;
  border-bottom: 1px solid var(--border-color);
}

.rank-tab {
  flex: 1;
  padding: 0.75rem;
  border: 2px solid var(--border-color);
  background: white;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
}

.rank-tab:hover {
  border-color: var(--secondary-color);
}

.rank-tab.active {
  background: var(--secondary-color);
  color: white;
  border-color: var(--secondary-color);
}

.ranking-list {
  padding: 1rem;
}

.ranking-level {
  margin-bottom: 1.5rem;
}

.ranking-level h3 {
  font-size: 1.1rem;
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--border-color);
}

.ranking-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.ranking-table th,
.ranking-table td {
  padding: 0.6rem 0.5rem;
  text-align: center;
}

.ranking-table th {
  background: var(--bg-color);
  color: var(--text-light);
  font-weight: 600;
}

.ranking-table tr:nth-child(even) {
  background: #f8f9fa;
}

.ranking-table tr:first-child td {
  font-weight: 600;
  color: var(--warning-color);
}

.no-data {
  color: var(--text-light);
  font-style: italic;
  padding: 1rem !important;
}

/* 반응형 */
@media (max-width: 480px) {
  .header h1 {
    font-size: 1.5rem;
  }

  .container {
    padding: 1rem;
  }

  .question-area {
    padding: 1.5rem;
  }

  .game-header {
    flex-direction: column;
    text-align: center;
  }

  .game-info,
  .game-stats {
    justify-content: center;
  }

  .result-stats {
    flex-direction: column;
    gap: 1rem;
  }

  .result-buttons,
  .game-buttons {
    flex-direction: column;
  }

  .ranking-table {
    font-size: 0.8rem;
  }

  .ranking-table th,
  .ranking-table td {
    padding: 0.5rem 0.3rem;
  }
}