/* style.css - Modern styles for PhongThuyQuaQua */

/* ========== CSS Custom Properties ========== */
:root {
  --color-gold: #D4A843;
  --color-gold-light: #f0dca0;
  --color-red: #C41E3A;
  --color-dark: #0f0f1a;
  --color-dark-secondary: #1a1a2e;
  --color-surface: #16162a;
  --color-text-light: #F5F5F5;
  --color-text-muted: #a0a0b8;
  --color-text-dark: #333333;

  --font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', sans-serif;
  --transition-speed: 0.3s;
  --border-radius: 8px;
  --border-radius-lg: 16px;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 4rem;
  --spacing-2xl: 6rem;
}

/* ========== Global Reset ========== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  color: var(--color-text-dark);
  background-color: var(--color-dark);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  padding-top: 64px;
}

/* ========== Typography ========== */
h1, h2, h3 { line-height: 1.3; font-weight: 700; }
h1 { font-size: 3rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.25rem; }
p { margin-bottom: var(--spacing-md); }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

a {
  color: var(--color-gold);
  text-decoration: none;
  transition: color var(--transition-speed) ease;
}
a:hover, a:focus { color: var(--color-red); }

/* ========== Buttons ========== */
.btn {
  display: inline-block;
  padding: 0.85rem 2rem;
  font-family: var(--font-family);
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  transition: all var(--transition-speed) ease;
  text-align: center;
}
.btn:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); }
.btn:active { transform: translateY(0); }
.btn-primary { background-color: var(--color-gold); color: var(--color-dark); }
.btn-primary:hover { background-color: #c49a38; color: var(--color-dark); }
.btn-outline {
  background: transparent;
  color: var(--color-text-light);
  border: 2px solid rgba(255,255,255,0.3);
}
.btn-outline:hover { border-color: var(--color-gold); color: var(--color-gold); }

/* ========== Utility ========== */
section { padding: var(--spacing-2xl) var(--spacing-lg); background-color: #ffffff; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 var(--spacing-md); }
.section-title {
  text-align: center;
  margin-bottom: var(--spacing-sm);
  color: var(--color-dark);
  font-size: 2.2rem;
}
.section-subtitle {
  text-align: center;
  color: #666;
  max-width: 700px;
  margin: 0 auto var(--spacing-xl);
  font-size: 1.05rem;
}

/* ========== Navigation ========== */
header {
  position: fixed;
  top: 0; left: 0; width: 100%;
  z-index: 1000;
  background: rgba(15, 15, 26, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(212, 168, 67, 0.1);
}
header nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.85rem var(--spacing-md);
}
header .logo {
  color: var(--color-gold);
  font-size: 1.3rem;
  font-weight: 700;
  letter-spacing: 0.5px;
}
.nav-links { display: flex; gap: var(--spacing-lg); list-style: none; }
.nav-links a {
  color: var(--color-text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 0.5rem 0;
  transition: color var(--transition-speed) ease;
}
.nav-links a:hover, .nav-links a:focus { color: var(--color-gold); }
.hamburger {
  display: none;
  background: none; border: none;
  color: var(--color-text-light);
  font-size: 1.5rem; cursor: pointer; padding: 0.25rem;
}
.hamburger:hover { transform: none; box-shadow: none; color: var(--color-gold); }

/* ========== Mobile Nav ========== */
@media (max-width: 767px) {
  .hamburger { display: block; }
  .nav-links {
    display: none; flex-direction: column;
    position: absolute; top: 100%; left: 0; width: 100%;
    background: rgba(15, 15, 26, 0.98);
    padding: var(--spacing-md); gap: 0;
    border-bottom: 1px solid rgba(212, 168, 67, 0.1);
  }
  .nav-links.active { display: flex; }
  .nav-links li { border-bottom: 1px solid rgba(255,255,255,0.06); }
  .nav-links a { display: block; padding: 0.85rem 0; }
}

/* ========== Hero ========== */
#hero {
  min-height: 90vh;
  display: flex; align-items: center; justify-content: center;
  text-align: center;
  background: linear-gradient(160deg, #0f0f1a 0%, #1a1a2e 30%, #2a1a3e 60%, #0f0f1a 100%);
  position: relative; overflow: hidden;
}
#hero::before {
  content: '';
  position: absolute; top: 0; left: 0; width: 100%; height: 100%;
  background:
    radial-gradient(ellipse at 20% 50%, rgba(212,168,67,0.12) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 30%, rgba(196,30,58,0.08) 0%, transparent 50%),
    radial-gradient(circle at 50% 80%, rgba(212,168,67,0.06) 0%, transparent 40%);
  pointer-events: none;
}
#hero::after {
  content: '';
  position: absolute; bottom: 0; left: 0; width: 100%; height: 120px;
  background: linear-gradient(to top, #ffffff, transparent);
  pointer-events: none;
}
.hero-content {
  position: relative; z-index: 1;
  max-width: 800px; padding: var(--spacing-lg);
}
.hero-tag {
  display: inline-block;
  color: var(--color-gold);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: var(--spacing-md);
  opacity: 0.9;
}
#hero h1 {
  color: var(--color-text-light);
  font-size: 3.5rem;
  margin-bottom: var(--spacing-md);
  letter-spacing: -0.5px;
}
#hero h1::after {
  content: '';
  display: block;
  width: 60px; height: 3px;
  background: var(--color-gold);
  margin: var(--spacing-md) auto 0;
  border-radius: 2px;
}
.hero-subtitle {
  color: var(--color-text-muted);
  font-size: 1.15rem;
  line-height: 1.8;
  margin-bottom: var(--spacing-lg);
}
.hero-actions { display: flex; gap: var(--spacing-md); justify-content: center; flex-wrap: wrap; }

/* ========== Features ========== */
#features { background: #fafafa; }
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
}
.feature-card {
  background: #ffffff;
  padding: var(--spacing-lg);
  border-radius: var(--border-radius-lg);
  text-align: center;
  transition: all var(--transition-speed) ease;
  border: 1px solid #f0f0f0;
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 40px rgba(0,0,0,0.08);
  border-color: var(--color-gold-light);
}
.feature-icon { font-size: 2.5rem; margin-bottom: var(--spacing-md); }
.feature-card h3 { margin-bottom: var(--spacing-sm); color: var(--color-dark); font-size: 1.1rem; }
.feature-card p { color: #666; font-size: 0.95rem; line-height: 1.7; margin-bottom: 0; }

/* ========== Course Sections ========== */
.course-badge {
  display: inline-block;
  background: linear-gradient(135deg, var(--color-gold), #e8c060);
  color: var(--color-dark);
  padding: 0.3rem 1rem;
  border-radius: 50px;
  font-weight: 700;
  font-size: 0.85rem;
  margin-bottom: var(--spacing-md);
  letter-spacing: 0.5px;
}
.course-title { color: var(--color-dark); margin-bottom: var(--spacing-sm); }
.course-scene-count {
  display: inline-block;
  background-color: rgba(212,168,67,0.15);
  color: var(--color-dark);
  padding: 0.25rem 0.75rem;
  border-radius: 50px;
  font-weight: 600;
  font-size: 0.85rem;
  margin-bottom: var(--spacing-md);
}
.course-description {
  color: #555;
  max-width: 800px;
  margin-bottom: var(--spacing-lg);
  line-height: 1.8;
}
.course-outline {
  list-style: none;
  padding-left: 0;
  margin-bottom: var(--spacing-lg);
}
.course-outline li {
  padding: 0.5rem 0 0.5rem 1.5rem;
  color: #555;
  position: relative;
}
.course-outline li::before {
  content: '✦';
  position: absolute;
  left: 0;
  color: var(--color-gold);
  font-size: 0.75rem;
  top: 0.65rem;
}
.course-layout { display: flex; flex-direction: column; gap: var(--spacing-lg); }
.course-content { flex: 1; }
.course-media { flex: 1; }
.course-media .video-container { max-width: 100%; }

.video-container { position: relative; width: 100%; max-width: 800px; }
.video-container video {
  display: block; width: 100%; height: auto;
  aspect-ratio: 16 / 9;
  object-fit: contain;
  background-color: #000;
  border-radius: var(--border-radius-lg);
}
.video-error {
  background-color: var(--color-red);
  color: var(--color-text-light);
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  text-align: center;
  margin-top: var(--spacing-sm);
}

#course-2 { background: #fafafa; }

/* ========== Stats ========== */
#stats {
  background: linear-gradient(160deg, var(--color-dark) 0%, var(--color-dark-secondary) 100%);
  padding: var(--spacing-xl) var(--spacing-lg);
}
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
  text-align: center;
}
.stat-number {
  display: block;
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-gold);
  margin-bottom: var(--spacing-sm);
}
.stat-label {
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

/* ========== Instructor ========== */
#instructor { background-color: #ffffff; }
.instructor-container {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
}
.instructor-image {
  flex: 0 0 250px;
  width: 250px; height: 250px;
  border-radius: 50%;
  overflow: hidden;
  background-color: transparent;
  box-shadow: 0 8px 32px rgba(212,168,67,0.2);
}
.instructor-image img {
  width: 100%; height: 100%;
  object-fit: cover;
  border-radius: 50%;
}
.instructor-info { flex: 1; }
.instructor-info h2 {
  color: var(--color-dark);
  font-size: 2.2rem;
  margin-bottom: var(--spacing-md);
}
.instructor-intro {
  color: #555;
  margin-bottom: var(--spacing-lg);
  line-height: 1.8;
}
.instructor-feature, .instructor-philosophy { margin-bottom: var(--spacing-lg); }
.instructor-feature h3, .instructor-philosophy h3 {
  color: var(--color-gold);
  margin-bottom: var(--spacing-sm);
  font-size: 1.1rem;
}
.instructor-feature p, .instructor-philosophy p {
  color: #555;
  line-height: 1.8;
}

/* ========== FAQ Section ========== */
#faq { background: #fafafa; }
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  background: #ffffff;
  border: 1px solid #f0f0f0;
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-lg);
  margin-bottom: var(--spacing-md);
  transition: all var(--transition-speed) ease;
}
.faq-item:hover {
  border-color: var(--color-gold-light);
  box-shadow: 0 4px 16px rgba(0,0,0,0.05);
}
.faq-item h3 {
  color: var(--color-dark);
  font-size: 1.1rem;
  margin-bottom: var(--spacing-sm);
}
.faq-item p {
  color: #555;
  line-height: 1.8;
  margin-bottom: 0;
}

/* ========== Footer ========== */
footer {
  background-color: var(--color-dark);
  color: var(--color-text-light);
  padding: var(--spacing-xl) var(--spacing-lg);
  text-align: center;
}
.footer-content {
  display: flex; flex-direction: column;
  align-items: center; gap: var(--spacing-lg);
}
.footer-copyright { font-size: 0.9rem; opacity: 0.6; margin-bottom: var(--spacing-sm); }
.footer-domain { color: var(--color-gold); font-weight: 600; font-size: 1rem; }
.footer-social { display: flex; gap: var(--spacing-md); }
.social-link {
  color: var(--color-text-muted);
  font-weight: 500;
  padding: 0.5rem 1.25rem;
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 50px;
  font-size: 0.9rem;
  transition: all var(--transition-speed) ease;
}
.social-link:hover {
  background-color: var(--color-gold);
  color: var(--color-dark);
  border-color: var(--color-gold);
}
.footer-top a {
  color: var(--color-text-muted);
  font-size: 0.85rem;
}
.footer-top a:hover { color: var(--color-gold); }

/* ========== Desktop (>= 1024px) ========== */
@media (min-width: 1024px) {
  .course-layout {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--spacing-xl);
  }
  .course-content { flex: 1 1 50%; }
  .course-media { flex: 1 1 45%; position: sticky; top: 80px; }
}

/* ========== Tablet (768-1023px) ========== */
@media (min-width: 768px) and (max-width: 1023px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: var(--spacing-xl); }
  .course-media .video-container { max-width: 600px; }
  .instructor-image { flex: 0 0 200px; width: 200px; height: 200px; }
  section { padding: var(--spacing-xl) var(--spacing-md); }
}

/* ========== Mobile (< 768px) ========== */
@media (max-width: 767px) {
  section { padding: var(--spacing-xl) var(--spacing-md); }
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }
  #hero { min-height: 80vh; }
  #hero h1 { font-size: 2.2rem; }
  .hero-subtitle { font-size: 1rem; }
  .hero-actions { flex-direction: column; align-items: center; }
  .features-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: var(--spacing-lg); }
  .stat-number { font-size: 2rem; }
  .instructor-container { flex-direction: column; align-items: center; text-align: center; }
  .instructor-image { flex: none; width: 180px; height: 180px; }
  .footer-social { flex-direction: column; gap: var(--spacing-sm); }
}