/* ===== CSS Variables ===== */
:root {
  --color-primary: #4A90E2;
  --color-secondary: #7ED321;
  --color-success: #50E3C2;
  --color-error: #FF6B6B;
  --color-bg: #F9F9F9;
  --color-text: #333333;
  --color-card-bg: #FFFFFF;
  --color-border: #E5E7EB;
  
  --font-size-small: 16px;
  --font-size-medium: 18px;
  --font-size-large: 20px;
  --font-size-xlarge: 32px;
  --font-size-huge: 48px;
  
  --spacing-xs: 8px;
  --spacing-sm: 16px;
  --spacing-md: 24px;
  --spacing-lg: 32px;
  --spacing-xl: 48px;
  
  --border-radius: 12px;
  --border-radius-lg: 16px;
  
  --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
}

/* ===== Global Styles ===== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Noto Sans KR', 'Apple SD Gothic Neo', 'Malgun Gothic', sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  font-size: var(--font-size-medium);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: var(--spacing-md);
}

body.font-small { font-size: var(--font-size-small); }
body.font-medium { font-size: var(--font-size-medium); }
body.font-large { font-size: var(--font-size-large); }

#app {
  width: 100%;
  max-width: 800px;
  margin: 0 auto;
}

/* ===== Typography ===== */
h1 {
  font-size: var(--font-size-xlarge);
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--spacing-lg);
  color: var(--color-primary);
}

h2 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: var(--spacing-md);
  text-align: center;
}

/* ===== Card Component ===== */
.card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  box-shadow: var(--shadow);
  animation: fadeIn 0.3s ease-in;
}

/* ===== Button Styles ===== */
button {
  min-width: 60px;
  min-height: 60px;
  padding: 14px 24px;
  font-size: var(--font-size-medium);
  font-weight: 500;
  font-family: inherit;
  border: 2px solid var(--color-primary);
  border-radius: var(--border-radius);
  background: var(--color-primary);
  color: white;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: var(--shadow);
}

button:hover {
  transform: scale(1.05);
  box-shadow: var(--shadow-lg);
}

button:active {
  transform: scale(0.95);
}

button:focus {
  outline: 3px solid rgba(74, 144, 226, 0.3);
  outline-offset: 2px;
}

button.secondary {
  background: white;
  color: var(--color-primary);
}

button.secondary:hover {
  background: #f0f7ff;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* ===== Input Styles ===== */
input[type="text"] {
  width: 100%;
  padding: 16px 20px;
  font-size: 24px;
  font-family: inherit;
  border: 3px solid var(--color-border);
  border-radius: var(--border-radius);
  background: white;
  transition: all 0.2s ease;
  text-align: center;
}

input[type="text"]:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 4px rgba(74, 144, 226, 0.1);
}

input[type="text"].correct {
  border-color: var(--color-success);
  animation: successShake 0.5s ease;
}

input[type="text"].wrong {
  border-color: var(--color-error);
  animation: errorShake 0.5s ease;
}

/* ===== Layout Components ===== */
.container {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  min-height: 400px;
}

.level-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--spacing-md);
  margin: var(--spacing-lg) 0;
}

.level-card {
  background: white;
  border: 3px solid var(--color-border);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
  min-height: 200px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: var(--spacing-sm);
}

.level-card:hover {
  border-color: var(--color-primary);
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.level-card:active {
  transform: translateY(-2px);
}

.level-icon {
  font-size: 48px;
  margin-bottom: var(--spacing-sm);
}

.level-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--spacing-xs);
}

.level-description {
  font-size: var(--font-size-small);
  color: #666;
  margin-bottom: var(--spacing-sm);
}

.level-stats {
  font-size: 14px;
  color: #999;
}

/* ===== Game Screen ===== */
.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
  padding: var(--spacing-md);
  background: white;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
}

.progress-info {
  font-size: var(--font-size-medium);
  font-weight: 500;
}

.score-info {
  font-size: var(--font-size-medium);
  font-weight: 700;
  color: var(--color-primary);
}

.progress-bar {
  width: 100%;
  height: 12px;
  background: #E5E7EB;
  border-radius: 6px;
  overflow: hidden;
  margin-bottom: var(--spacing-lg);
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-secondary));
  transition: width 0.3s ease;
  border-radius: 6px;
}

.word-display {
  font-size: var(--font-size-huge);
  font-weight: 700;
  text-align: center;
  color: var(--color-primary);
  margin: var(--spacing-xl) 0;
  min-height: 80px;
  display: flex;
  align-items: center;
  justify-content: center;
  animation: wordAppear 0.3s ease;
}

.character-container {
  text-align: center;
  margin: var(--spacing-lg) 0;
}

.character {
  font-size: 120px;
  display: inline-block;
  transition: transform 0.3s ease;
}

.character.jump {
  animation: jump 0.5s ease;
}

.character.shake {
  animation: headShake 0.5s ease;
}

.game-form {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.button-group {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Result Screen ===== */
.result-container {
  text-align: center;
}

.result-emoji {
  font-size: 80px;
  margin: var(--spacing-lg) 0;
  animation: scaleIn 0.5s ease;
}

.result-grade {
  font-size: 72px;
  font-weight: 700;
  color: var(--color-primary);
  margin: var(--spacing-md) 0;
  animation: scaleIn 0.6s ease;
}

.result-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: var(--spacing-md);
  margin: var(--spacing-lg) 0;
}

.stat-item {
  background: #F0F7FF;
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
}

.stat-label {
  font-size: var(--font-size-small);
  color: #666;
  margin-bottom: var(--spacing-xs);
}

.stat-value {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-primary);
}

.result-message {
  font-size: 20px;
  color: #666;
  margin: var(--spacing-lg) 0;
  line-height: 1.8;
}

/* ===== Settings Screen ===== */
.settings-group {
  margin-bottom: var(--spacing-lg);
  padding-bottom: var(--spacing-lg);
  border-bottom: 1px solid var(--color-border);
}

.settings-group:last-child {
  border-bottom: none;
}

.settings-label {
  display: block;
  font-weight: 500;
  margin-bottom: var(--spacing-sm);
}

.toggle-switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 34px;
}

.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: #ccc;
  transition: .4s;
  border-radius: 34px;
}

.slider:before {
  position: absolute;
  content: "";
  height: 26px;
  width: 26px;
  left: 4px;
  bottom: 4px;
  background-color: white;
  transition: .4s;
  border-radius: 50%;
}

input:checked + .slider {
  background-color: var(--color-primary);
}

input:checked + .slider:before {
  transform: translateX(26px);
}

.button-options {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.option-button {
  min-width: auto;
  min-height: auto;
  padding: 10px 20px;
  background: white;
  color: var(--color-text);
  border: 2px solid var(--color-border);
}

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

/* ===== Animations ===== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes wordAppear {
  from {
    opacity: 0;
    transform: scale(0.8);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes jump {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  25% { transform: translateY(-30px) rotate(-5deg); }
  50% { transform: translateY(-40px) rotate(0deg); }
  75% { transform: translateY(-30px) rotate(5deg); }
}

@keyframes headShake {
  0%, 100% { transform: translateX(0) rotate(0deg); }
  25% { transform: translateX(-10px) rotate(-5deg); }
  50% { transform: translateX(10px) rotate(5deg); }
  75% { transform: translateX(-10px) rotate(-5deg); }
}

@keyframes successShake {
  0%, 100% { transform: scale(1); }
  25% { transform: scale(1.05); }
  50% { transform: scale(1.1); }
  75% { transform: scale(1.05); }
}

@keyframes errorShake {
  0%, 100% { transform: translateX(0); }
  10%, 30%, 50%, 70%, 90% { transform: translateX(-10px); }
  20%, 40%, 60%, 80% { transform: translateX(10px); }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: scale(0.5);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
  :root {
    --font-size-xlarge: 24px;
    --font-size-huge: 36px;
  }
  
  .level-grid {
    grid-template-columns: 1fr;
  }
  
  .game-header {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
  
  .result-grade {
    font-size: 48px;
  }
  
  .character {
    font-size: 80px;
  }
}

/* ===== Accessibility ===== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

*:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}