@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --secondary: #f59e0b;
  --success: #10b981;
  --danger: #ef4444;
  --bg: #0f172a;
  --bg-card: #1e293b;
  --text: #f1f5f9;
  --text-dim: #94a3b8;
  --border: #334155;
  --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
  --radius: 12px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: linear-gradient(135deg, var(--bg) 0%, #1a243a 100%);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 0;
}

/* === LANDING PAGE STYLES === */
body.landing-page {
  padding: 0;
}

.hero {
  min-height: 100vh;
  position: relative;
  overflow: hidden;
}

.nav-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem 3rem;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(10px);
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.5rem;
  font-weight: 700;
}

.nav-links {
  display: flex;
  gap: 2rem;
}

.nav-links a {
  color: var(--text-dim);
  text-decoration: none;
  transition: color 0.3s;
}

.nav-links a:hover {
  color: var(--primary);
}

.hero-content {
  max-width: 900px;
  margin: 15rem auto 5rem;
  text-align: center;
  padding: 0 2rem;
}

.hero-content h1 {
  font-size: 3.5rem;
  margin-bottom: 1.5rem;
  line-height: 1.1;
}

.hero-content p {
  font-size: 1.2rem;
  color: var(--text-dim);
  margin-bottom: 2rem;
}

.cta-button {
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  color: white;
  padding: 1rem 3rem;
  border: none;
  border-radius: var(--radius);
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.3s;
}

.cta-button:hover {
  transform: translateY(-2px);
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 3rem;
  margin-top: 4rem;
}

.stat {
  text-align: center;
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--primary);
}

.stat-label {
  color: var(--text-dim);
}

.features-section,
.how-section {
  padding: 5rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.features-section h2,
.how-section h2 {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: 3rem;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--bg-card);
  padding: 2rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  text-align: center;
  transition: transform 0.3s;
}

.feature-card:hover {
  transform: translateY(-5px);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.steps-container {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.step {
  text-align: center;
  max-width: 200px;
}

.step-number {
  width: 60px;
  height: 60px;
  background: var(--primary);
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0 auto 1rem;
}

.step-arrow {
  font-size: 2rem;
  color: var(--text-dim);
}

.auth-section {
  /*background: var(--bg-card);*/
  padding: 3rem 0;
  margin-top: 3rem;
  display: flex;
  align-items: center;
  flex-direction: column;
}

/* === AUTH FORMS (Landing & Game) === */
.auth-container {
  max-width: 450px;
  width: 100%;
  background: var(--bg-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 2rem;
  border: 1px solid var(--border);
}

.auth-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.tab-btn {
  flex: 1;
  padding: 0.75rem;
  border: none;
  background: var(--bg);
  color: var(--text-dim);
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
}

.tab-btn.active {
  background: var(--primary);
  color: white;
}

.auth-form {
  display: none;
}

.auth-form.active {
  display: block;
}

.auth-form h2 {
  margin-bottom: 1.5rem;
  font-size: 1.5rem;
}

.auth-form input[type="text"],
.auth-form input[type="password"],
.auth-form input[type="number"] {
  width: 100%;
  padding: 0.75rem 1rem;
  margin-bottom: 1rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  color: var(--text);
  font-size: 1rem;
}

.toeic-toggle {
  margin: 1.5rem 0;
}

.checkbox-wrapper {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  padding: 1rem;
  border-radius: var(--radius);
  background: rgba(99, 102, 241, 0.05);
  border: 1px solid var(--border);
  transition: var(--transition);
}

.checkbox-wrapper:hover {
  background: rgba(99, 102, 241, 0.1);
  border-color: var(--primary);
}

input[type="checkbox"] {
  width: 20px;
  height: 20px;
  cursor: pointer;
}

.toeic-inputs {
  margin-top: 1rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: var(--transition);
}

.toeic-inputs.visible {
  opacity: 1;
  max-height: 200px;
}

.input-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.input-group label {
  font-size: 0.9rem;
  color: var(--text-dim);
}

/* Beta Key Input Styling */
.beta-key-group {
  margin: 1.5rem 0;
  padding: 1.25rem;
  background: rgba(99, 102, 241, 0.05);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.beta-key-group label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 0.75rem;
}

.required-indicator {
  color: var(--danger);
  font-weight: 700;
}

.beta-key-group input {
  width: 100%;
  padding: 0.875rem 1rem;
  font-family: 'Monaco', 'Courier New', monospace;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  border: 2px solid var(--border);
  border-radius: calc(var(--radius) - 2px);
  background: var(--bg);
  color: var(--text);
  transition: var(--transition);
}

.beta-key-group input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.beta-key-group input:valid {
  border-color: var(--success);
}

.beta-key-group input:invalid:not(:placeholder-shown) {
  border-color: var(--danger);
}

.input-hint {
  display: block;
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
  font-style: italic;
}

.btn-primary {
  width: 100%;
  padding: 1rem;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius);
  font-weight: 600;
  cursor: pointer;
  transition: background 0.3s;
}

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

.btn-secondary {
  width: 100%;
  padding: 1rem;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: background 0.3s;
}

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

.error-message {
  color: var(--danger);
  margin-top: 0.5rem;
  font-size: 0.9rem;
}

.success-message {
  color: var(--success);
  margin-top: 0.5rem;
  font-size: 0.9rem;
}

.guest-option {
  margin-top: 1.5rem;
  text-align: center;
}

/* === GAME SCREEN === */
#game-screen {
  max-width: 1400px;
  margin: 0 auto;
  padding: 2rem;
}

.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding: 1.5rem;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.player-info {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.level-badge {
  width: 50px;
  height: 50px;
  background: var(--primary);
  border-radius: 50%;
  display: grid;
  place-items: center;
  font-weight: 700;
  font-size: 1.2rem;
}

.xp-bar-container {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.xp-bar {
  width: 200px;
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
}

.xp-progress {
  height: 100%;
  background: linear-gradient(90deg, var(--secondary), var(--primary));
  transition: width 0.3s;
}

.xp-text {
  font-size: 0.8rem;
  color: var(--text-dim);
}

.user-menu {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.btn-dashboard {
  padding: 0.5rem 1rem;
  background: var(--danger);
  color: white;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
}

/* Game main layout */
.game-main {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
}

.dashboard-panel,
.stats-panel {
  background: var(--bg-card);
  padding: 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.dashboard-panel h2,
.stats-panel h2 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
}

.skills-container {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.skill-bar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.skill-name {
  font-size: 0.9rem;
  width: 80px;
}

.skill-progress {
  flex: 1;
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
}

.skill-fill {
  height: 100%;
  background: var(--success);
  transition: width 0.3s;
}

.skill-value {
  font-size: 0.8rem;
  color: var(--text-dim);
  width: 40px;
  text-align: right;
}

.uncertainty-meter {
  margin-top: 1.5rem;
}

.meter {
  width: 100%;
  height: 8px;
  background: var(--border);
  border-radius: 4px;
  overflow: hidden;
}

.meter-fill {
  height: 100%;
  background: var(--primary);
  transition: width 0.3s;
}

/* Question panel */
.question-panel {
  background: var(--bg-card);
  padding: 2rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.zpd-indicator {
  margin-bottom: 1.5rem;
}

.zpd-bar {
  position: relative;
  height: 20px;
  background: var(--border);
  border-radius: 10px;
  overflow: hidden;
}

.zpd-zone {
  position: absolute;
  height: 100%;
  background: rgba(16, 185, 129, 0.3);
  border: 2px solid var(--success);
  border-radius: 10px;
}

.difficulty-marker {
  position: absolute;
  width: 4px;
  height: 100%;
  background: var(--secondary);
  transition: left 0.3s;
}

.zpd-labels {
  display: flex;
  justify-content: space-between;
  margin-top: 0.5rem;
  font-size: 0.9rem;
}

.zpd-hit {
  color: var(--success);
}

.zpd-miss {
  color: var(--danger);
}

.question-content {
  margin-bottom: 2rem;
}

.topic-badge {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  background: var(--primary);
  border-radius: var(--radius);
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.difficulty-label {
  display: inline-block;
  padding: 0.25rem 0.75rem;
  background: var(--border);
  border-radius: var(--radius);
  font-size: 0.8rem;
  margin-left: 0.5rem;
}

#question-text {
  margin: 1.5rem 0;
  font-size: 1.2rem;
  line-height: 1.5;
}

.options-container {
  margin-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option {
  padding: 1rem 1.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
}

.option:hover {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.05);
}

.option.selected {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.1);
}

#submit-btn {
  width: 100%;
  margin-top: 2rem;
}

#submit-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

#submit-btn:disabled:hover {
  transform: none;
  background: var(--primary);
  /* Keep the original background */
  opacity: 0.5;
  cursor: not-allowed;
}

.feedback {
  margin-top: 2rem;
  padding: 1.5rem;
  background: rgba(16, 185, 129, 0.1);
  border: 1px solid var(--success);
  border-radius: var(--radius);
}

.incorrect-feedback {
  background: rgba(239, 68, 68, 0.1);
  border-color: var(--danger);
}

.feedback-content {
  margin-bottom: 1rem;
}

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

.stat-value {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-dim);
}

/* === RESPONSIVE === */
@media (max-width: 768px) {
  .hero-content h1 {
    font-size: 2.5rem;
  }

  .nav-bar {
    padding: 1rem;
  }

  .nav-links {
    display: none;
  }

  .hero-stats {
    flex-direction: column;
    gap: 1.5rem;
  }

  .toeic-inputs {
    grid-template-columns: 1fr;
  }

  .game-main {
    grid-template-columns: 1fr;
  }

  .game-header {
    flex-direction: column;
    gap: 1rem;
  }
}

/* ==================== QUESTION FORMAT ADAPTATIONS ==================== */

/* Article Container */
.article-container {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(15, 23, 42, 0.8) 100%);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  max-height: 300px;
  overflow-y: auto;
  position: relative;
  box-shadow: var(--shadow);
}

.article-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--primary);
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.article-label::before {
  content: '📄';
}

.article-text {
  font-size: 1.1rem;
  line-height: 1.8;
  color: var(--text);
  white-space: pre-wrap;
}

/* Grammar Blanks */
.blank-marker {
  display: inline-block;
  padding: 0.2rem 0.6rem;
  margin: 0 0.2rem;
  border-radius: 6px;
  font-weight: bold;
  background: var(--bg);
  border: 2px solid var(--border);
  color: var(--text-dim);
  transition: all 0.3s ease;
  min-width: 2.5rem;
  text-align: center;
}

.blank-marker.current-blank {
  background: var(--secondary);
  border-color: var(--secondary);
  color: var(--bg);
  box-shadow: 0 0 15px rgba(245, 158, 11, 0.4);
  animation: pulse 2s infinite;
}

.blank-marker.answered-blank {
  background: var(--bg-card);
  border-color: var(--primary);
  color: var(--primary);
}

.blank-marker.correct-blank {
  background: var(--success);
  border-color: var(--success);
  color: white;
}

.blank-marker.incorrect-blank {
  background: var(--danger);
  border-color: var(--danger);
  color: white;
  text-decoration: line-through;
}

@keyframes pulse {

  0%,
  100% {
    transform: scale(1);
  }

  50% {
    transform: scale(1.05);
  }
}

/* Sub-question Navigation */
.sub-question-nav {
  text-align: center;
  padding: 0.5rem 1rem;
  background: var(--bg);
  border-radius: 20px;
  display: inline-block;
  margin: 0 auto 1rem auto;
  font-size: 0.9rem;
  color: var(--text-dim);
  border: 1px solid var(--border);
  font-weight: 600;
}

.question-meta {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
  flex-wrap: wrap;
}

.question-prompt {
  margin: 1rem 0;
  font-size: 1.2rem;
  line-height: 1.5;
  color: var(--text);
}

/* Option Styling Enhancements */
.option {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.25rem;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: var(--transition);
  margin-bottom: 0.75rem;
}

.option:hover {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.05);
  transform: translateX(5px);
}

.option.selected {
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.15);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.option-letter {
  font-weight: 800;
  color: var(--primary);
  font-size: 1.1rem;
  min-width: 1.5rem;
}

.option-text {
  flex: 1;
  color: var(--text);
}

/* Feedback Enhancements */
.zpd-bonus {
  display: inline-block;
  background: linear-gradient(135deg, var(--secondary), #fbbf24);
  color: #000;
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  font-size: 0.8rem;
  font-weight: 700;
  margin-left: 0.5rem;
  animation: bounce 0.5s;
}

@keyframes bounce {

  0%,
  100% {
    transform: translateY(0);
  }

  50% {
    transform: translateY(-5px);
  }
}

/* Streak Display */
.streak-display {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  background: rgba(245, 158, 11, 0.1);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  color: var(--secondary);
  font-weight: 700;
}

/* Scrollbar for Article */
.article-container::-webkit-scrollbar {
  width: 8px;
}

.article-container::-webkit-scrollbar-track {
  background: var(--bg);
  border-radius: 4px;
}

.article-container::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}

.article-container::-webkit-scrollbar-thumb:hover {
  background: var(--primary);
}

/* Responsive Adjustments for Articles */
@media (max-width: 768px) {
  .article-container {
    max-height: 200px;
    padding: 1rem;
  }

  .article-text {
    font-size: 1rem;
    line-height: 1.6;
  }

  .blank-marker {
    padding: 0.1rem 0.4rem;
    min-width: 2rem;
  }

  .option {
    padding: 0.875rem 1rem;
  }
}

.option.answered {
  pointer-events: none;
  cursor: default;
}

.option.answered:not(.selected) {
  opacity: 0.5;
}

.option.answered.selected {
  /* Keep selected styling */
  border-color: var(--primary);
  background: rgba(99, 102, 241, 0.1);
}

@keyframes floatUp {
  0% {
    opacity: 1;
    transform: translateX(-50%) translateY(0) scale(1);
  }

  100% {
    opacity: 0;
    transform: translateX(-50%) translateY(-50px) scale(0.8);
  }
}

.floating-xp {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

.level-up {
  animation: levelUpPulse 2s ease-out forwards !important;
}

@keyframes levelUpPulse {
  0% {
    opacity: 0;
    transform: translateX(-50%) translateY(20px) scale(0.5);
  }

  20% {
    opacity: 1;
    transform: translateX(-50%) translateY(0) scale(1.2);
  }

  40% {
    transform: translateX(-50%) translateY(-10px) scale(1);
  }

  100% {
    opacity: 0;
    transform: translateX(-50%) translateY(-60px) scale(0.9);
  }
}

/* XP Bar glow effect on increase */
.xp-progress {
  position: relative;
  overflow: hidden;
}

.xp-progress::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.4), transparent);
  animation: shimmer 2s infinite;
  opacity: 0;
}

.xp-progress.active::after {
  opacity: 1;
}

@keyframes shimmer {
  0% {
    transform: translateX(-100%);
  }

  100% {
    transform: translateX(100%);
  }
}

.lang-switch button {
  border: none;
  border-radius: 12px;
  color: whitesmoke;
  padding: 8px 10px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 16px;
  margin: 4px 2px;
  transition-duration: 0.4s;
  cursor: pointer;
  background-color: #6366f1;
  font-weight: 600;
}