/* ============================================
   Learn JavaScript — Design System
   Warm educational aesthetic, amber/orange accents
   ============================================ */

:root {
  /* Amber / Orange palette */
  --amber-50: #fffbeb;
  --amber-100: #fef3c7;
  --amber-200: #fde68a;
  --amber-300: #fcd34d;
  --amber-400: #fbbf24;
  --amber-500: #f59e0b;
  --amber-600: #d97706;
  --amber-700: #b45309;
  --amber-800: #92400e;
  --amber-900: #78350f;
  --orange-500: #f97316;
  --orange-600: #ea580c;

  /* Neutrals */
  --bg: #fefcf8;
  --bg-section: #fffbf5;
  --text: #1f2937;
  --text-muted: #6b7280;
  --border: #e5e7eb;
  --white: #ffffff;

  /* Code block (dark) */
  --code-bg: #1e1e2e;
  --code-text: #cdd6f4;
  --code-accent: #fbbf24;
  --code-keyword: #cba6f7;
  --code-string: #a6e3a1;
  --code-comment: #6c7086;

  /* UI */
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 14px rgba(217, 119, 6, 0.12);
  --shadow-lg: 0 10px 40px rgba(217, 119, 6, 0.15);
  --transition: 0.2s ease;

  /* Fonts */
  --font-body: 'Nunito', sans-serif;
  --font-code: 'Fira Code', monospace;
}

/* Base */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1.05rem;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  min-height: 100vh;
}

/* Typography */
h1, h2, h3 { font-weight: 800; margin: 0 0 0.5em; }
h1 { font-size: clamp(2rem, 5vw, 3rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); color: var(--amber-800); }
a { color: var(--amber-600); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ========== Language Selector ========== */
.language-selector {
  position: fixed;
  top: 1rem;
  right: 1rem;
  z-index: 100;
  display: flex;
  gap: 0;
  background: var(--white);
  border-radius: var(--radius-sm);
  padding: 4px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.lang-btn {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.9rem;
  padding: 0.4rem 0.75rem;
  border: none;
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: 6px;
  transition: var(--transition);
}
.lang-btn:hover { color: var(--amber-600); background: var(--amber-50); }
.lang-btn.active { background: var(--amber-500); color: white; }

/* ========== Floating Navigation ========== */
.floating-nav {
  position: fixed;
  left: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 90;
  background: var(--white);
  border-radius: var(--radius);
  padding: 0.75rem 0.5rem;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.nav-link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border-radius: var(--radius-sm);
  color: var(--text-muted);
  font-weight: 700;
  font-size: 0.85rem;
  transition: var(--transition);
}
.nav-link:hover { background: var(--amber-100); color: var(--amber-700); }
.nav-link.active { background: var(--amber-500); color: white; }
.nav-progress {
  height: 4px;
  width: 100%;
  margin-top: 0.5rem;
  background: var(--border);
  border-radius: 2px;
  overflow: hidden;
}
.floating-nav .nav-progress::after {
  content: '';
  display: block;
  height: 100%;
  width: var(--progress-width, 0%);
  background: var(--amber-500);
  border-radius: 2px;
  transition: width 0.3s ease;
}

/* ========== Hero Section ========== */
.hero-section {
  min-height: 85vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 4rem 2rem;
  background: linear-gradient(135deg, var(--amber-50) 0%, var(--bg) 50%);
  position: relative;
  overflow: hidden;
}
.hero-section::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 60%;
  height: 120%;
  background: radial-gradient(circle, rgba(251, 191, 36, 0.15) 0%, transparent 70%);
  pointer-events: none;
}
.hero-content { position: relative; z-index: 1; max-width: 600px; }
.hero-title {
  animation: slideDown 0.8s ease-out;
  letter-spacing: -0.02em;
}
.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  animation: slideUp 0.8s ease-out 0.2s both;
}
.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 2rem;
  animation: slideUp 0.8s ease-out 0.4s both;
}
.stat {
  font-size: 1rem;
  color: var(--text-muted);
}
.stat strong { color: var(--amber-700); margin-right: 0.25rem; }
.cta-button {
  display: inline-block;
  padding: 0.9rem 2rem;
  background: var(--amber-500);
  color: white;
  font-weight: 700;
  font-size: 1.1rem;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  transition: var(--transition);
  animation: bounceIn 0.8s ease-out 0.6s both;
  box-shadow: var(--shadow);
}
.cta-button:hover {
  background: var(--amber-600);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  margin-top: 1.5rem;
}
.cta-button-pdf {
  background: var(--white);
  color: var(--amber-700);
  border: 2px solid var(--amber-400);
}
.cta-button-pdf:hover {
  background: var(--amber-50);
  border-color: var(--amber-500);
  color: var(--amber-800);
}
.pdf-btn-icon { margin-right: 0.35rem; }

/* ========== Learning Sections ========== */
.learning-section {
  padding: 4rem 2rem;
  max-width: 900px;
  margin: 0 auto;
  background: var(--bg-section);
  border-top: 1px solid var(--border);
}
.learning-section:nth-child(odd) { background: var(--bg); }
.section-title { margin-bottom: 0.5rem; }
.section-desc {
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  font-size: 1.05rem;
}

/* ========== Code Block ========== */
.code-block {
  background: var(--code-bg);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-bottom: 1rem;
  font-family: var(--font-code);
  font-size: 0.9rem;
  line-height: 1.6;
  overflow-x: auto;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
  position: relative;
}
.code-block pre { margin: 0; }
.code-block code {
  color: var(--code-text);
  background: none;
  padding: 0;
}
/* Simple syntax highlighting via spans — JS will add classes */
.code-block .keyword { color: var(--code-keyword); }
.code-block .string { color: var(--code-string); }
.code-block .comment { color: var(--code-comment); }
.code-block .number { color: var(--code-accent); }
.run-btn {
  margin-top: 1rem;
  padding: 0.5rem 1.25rem;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 0.95rem;
  background: var(--amber-500);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}
.run-btn:hover { background: var(--amber-600); transform: scale(1.02); }
.run-btn:active { transform: scale(0.98); }
.run-btn.ran { animation: pulse 0.5s ease; }

/* Input demo row */
.input-demo-row {
  display: flex;
  gap: 0.75rem;
  margin-top: 1rem;
  flex-wrap: wrap;
}
.input-demo-row #input-demo {
  flex: 1;
  min-width: 180px;
  padding: 0.5rem 0.75rem;
  font-family: var(--font-body);
  font-size: 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--white);
}
.input-demo-row #input-demo:focus {
  outline: none;
  border-color: var(--amber-500);
}

/* Demo output areas */
.demo-output {
  background: var(--white);
  border: 2px dashed var(--border);
  border-radius: var(--radius-sm);
  padding: 1rem 1.25rem;
  margin-bottom: 2rem;
  min-height: 3rem;
}
.demo-output p { margin: 0 0 0.5rem; color: var(--text-muted); font-size: 0.9rem; }
.input-result { font-family: var(--font-code); color: var(--amber-700); font-weight: 600; }
.dom-demo-box {
  padding: 1rem;
  background: var(--amber-100);
  color: var(--amber-900);
  border-radius: var(--radius-sm);
  font-weight: 600;
  transition: transform 0.3s ease;
}

/* ========== Quiz Component ========== */
.quiz-container {
  margin-top: 2rem;
  padding: 1.5rem;
  background: var(--white);
  border-radius: var(--radius);
  border: 2px solid var(--amber-200);
}
.quiz-container h4 {
  margin: 0 0 1rem;
  font-size: 1.1rem;
  color: var(--amber-800);
}
.quiz-options {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.quiz-option {
  padding: 0.75rem 1rem;
  background: var(--bg);
  border: 2px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
  font-family: var(--font-body);
  font-size: 1rem;
  text-align: left;
}
.quiz-option:hover:not(.disabled) { border-color: var(--amber-400); background: var(--amber-50); }
.quiz-option.disabled { opacity: 0.6; cursor: not-allowed; }
.quiz-option.correct { border-color: #10b981; background: #d1fae5; }
.quiz-option.incorrect { border-color: #ef4444; background: #fee2e2; }
.quiz-feedback {
  margin-top: 0.75rem;
  padding: 0.75rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  display: none;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.correct { background: #d1fae5; color: #065f46; }
.quiz-feedback.incorrect { background: #fee2e2; color: #991b1b; }
.quiz-score-bar {
  margin-top: 1rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.95rem;
  color: var(--text-muted);
}
.quiz-retry {
  margin-top: 0.75rem;
  padding: 0.5rem 1rem;
  font-family: var(--font-body);
  font-weight: 600;
  background: var(--amber-100);
  color: var(--amber-800);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}
.quiz-retry:hover { background: var(--amber-200); }

/* ========== Mini-game ========== */
.minigame-section { padding-bottom: 4rem; }
.minigame-area {
  background: var(--white);
  border-radius: var(--radius);
  padding: 2rem;
  border: 2px solid var(--amber-200);
  margin-bottom: 2rem;
}
.minigame-ui {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
  font-size: 1.1rem;
}
.minigame-board {
  position: relative;
  height: 280px;
  background: linear-gradient(180deg, var(--amber-50) 0%, var(--amber-100) 100%);
  border-radius: var(--radius-sm);
  margin-bottom: 1rem;
}
.minigame-target {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  padding: 1rem 1.5rem;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 1rem;
  background: var(--amber-500);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: transform 0.1s ease;
  box-shadow: var(--shadow);
}
.minigame-target:hover { transform: scale(1.05); }
.minigame-target:active { transform: scale(0.95); }
.minigame-start {
  display: block;
  width: 100%;
  padding: 0.75rem;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 1rem;
  background: var(--amber-500);
  color: white;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition);
}
.minigame-start:hover { background: var(--amber-600); }

/* ========== Footer ========== */
.site-footer {
  background: var(--amber-900);
  color: var(--amber-100);
  padding: 3rem 2rem;
  text-align: center;
}
.footer-content { max-width: 600px; margin: 0 auto; }
.site-footer h3 { color: white; margin-bottom: 1rem; }
.footer-links {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}
.footer-links a { color: var(--amber-200); }
.footer-links a:hover { color: white; text-decoration: none; }
.footer-credit { margin: 0; font-size: 0.9rem; opacity: 0.9; }

/* ========== Animations ========== */
@keyframes slideDown {
  from { opacity: 0; transform: translateY(-20px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes bounceIn {
  from { opacity: 0; transform: scale(0.9); }
  50% { transform: scale(1.05); }
  to { opacity: 1; transform: scale(1); }
}
@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}
.pulse { animation: pulse 0.6s ease 2; }
.slide-in { animation: slideUp 0.5s ease-out; }

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .floating-nav {
    left: 50%;
    top: auto;
    bottom: 1rem;
    transform: translateX(-50%);
    flex-direction: row;
    padding: 0.5rem 0.75rem;
  }
  .nav-list {
    flex-direction: row;
    gap: 0.35rem;
  }
  .nav-progress {
    display: none;
  }
  .language-selector { top: 0.5rem; right: 0.5rem; }
  .hero-section { min-height: 75vh; padding: 3rem 1rem; }
  .hero-stats { flex-direction: column; gap: 0.5rem; }
  .learning-section { padding: 3rem 1rem; }
  .code-block { font-size: 0.85rem; padding: 1rem; }
}

@media (max-width: 480px) {
  .nav-link { width: 2rem; height: 2rem; font-size: 0.8rem; }
  .floating-nav { padding: 0.4rem; }
}