@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+KR:wght@300;400;500;700&family=Outfit:wght@400;500;600;700&display=swap');

:root {
  --bg-gradient-start: #0f0a1c;
  --bg-gradient-mid: #180e2b;
  --bg-gradient-end: #090512;
  
  --card-bg: rgba(25, 17, 43, 0.65);
  --card-bg-hover: rgba(38, 26, 64, 0.85);
  --card-border: rgba(255, 255, 255, 0.08);
  --card-border-hover: rgba(236, 72, 153, 0.4);
  
  --primary-glow: #ec4899;
  --secondary-glow: #8b5cf6;
  --accent-cyan: #06b6d4;
  
  --text-main: #f3f4f6;
  --text-muted: #9ca3af;
  --text-dim: #6b7280;
  
  --badge-bg: rgba(236, 72, 153, 0.18);
  --badge-text: #f472b6;
  --badge-border: rgba(236, 72, 153, 0.3);
  
  --glass-blur: blur(16px);
  --radius-lg: 16px;
  --radius-md: 10px;
  --radius-sm: 6px;
  
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: 'Noto Sans KR', 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
  background: radial-gradient(circle at 50% 0%, var(--bg-gradient-mid) 0%, var(--bg-gradient-start) 50%, var(--bg-gradient-end) 100%);
  background-attachment: fixed;
  color: var(--text-main);
  min-height: 100vh;
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
}

/* Background Ambient Lighting Effect */
body::before {
  content: '';
  position: fixed;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 800px;
  height: 500px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.15) 0%, rgba(236, 72, 153, 0.08) 40%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
::-webkit-scrollbar-track {
  background: rgba(15, 10, 28, 0.9);
}
::-webkit-scrollbar-thumb {
  background: rgba(139, 92, 246, 0.3);
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(236, 72, 153, 0.5);
}

/* Layout Container */
.app-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 20px 80px 20px;
  position: relative;
  z-index: 1;
}

/* Header & Navbar */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 10, 28, 0.9);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-bottom: 1px solid var(--card-border);
  margin-bottom: 24px;
}

.header-inner {
  max-width: 1440px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: #fff;
  flex-shrink: 0;
}

.logo-icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-family: 'Outfit', sans-serif;
  font-size: 1.15rem;
  box-shadow: 0 0 16px rgba(236, 72, 153, 0.4);
}

.logo-text-group h1 {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  background: linear-gradient(135deg, #ffffff 0%, #d1d5db 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  white-space: nowrap;
}

.logo-text-group p {
  font-size: 0.72rem;
  color: var(--text-muted);
  white-space: nowrap;
}

/* Header Action Tools & Search Box */
.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-grow: 1;
  justify-content: flex-end;
}

.search-box {
  position: relative;
  width: 260px;
  max-width: 100%;
}

.search-box input {
  width: 100%;
  padding: 10px 16px 10px 38px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--card-border);
  border-radius: 20px;
  color: #fff;
  font-size: 0.85rem;
  outline: none;
  transition: var(--transition-fast);
}

.search-box input:focus {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--secondary-glow);
  box-shadow: 0 0 15px rgba(139, 92, 246, 0.25);
}

.search-icon {
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

/* Touch Scrollable Category Filter Bar for Mobile */
.filter-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-bottom: 28px;
  overflow-x: auto;
  padding: 4px 0 8px 0;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none; /* Firefox */
}

.filter-bar::-webkit-scrollbar {
  display: none; /* Chrome, Safari */
}

.filter-btn {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--card-border);
  padding: 8px 18px;
  border-radius: 20px;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
  flex-shrink: 0;
  transition: var(--transition-fast);
  touch-action: manipulation;
}

.filter-btn:hover, .filter-btn:active {
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-main);
  border-color: rgba(255, 255, 255, 0.2);
}

.filter-btn.active {
  background: linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));
  color: #fff;
  border-color: transparent;
  box-shadow: 0 4px 15px rgba(236, 72, 153, 0.35);
}

/* Hero Info Banner */
.hero-banner {
  text-align: center;
  padding: 16px 12px 28px 12px;
  max-width: 800px;
  margin: 0 auto;
}

.hero-banner h2 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 10px;
  letter-spacing: -0.5px;
  background: linear-gradient(135deg, #ffffff 30%, #f472b6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-banner p {
  font-size: 0.92rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.stats-pills {
  display: inline-flex;
  gap: 10px;
  margin-top: 14px;
  flex-wrap: wrap;
  justify-content: center;
}

.stat-pill {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--card-border);
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.78rem;
  color: var(--badge-text);
}

/* Video Grid Feed */
.video-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-top: 16px;
}

@media (max-width: 1200px) {
  .video-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 840px) {
  .video-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }
}

@media (max-width: 540px) {
  .video-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }
}

/* Lecture Card Component */
.lecture-card {
  background: var(--card-bg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--card-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  cursor: pointer;
  transition: var(--transition-smooth);
  display: flex;
  flex-direction: column;
  position: relative;
  transform: translateY(0);
  touch-action: manipulation;
}

.lecture-card:hover, .lecture-card:active {
  transform: translateY(-4px);
  background: var(--card-bg-hover);
  border-color: var(--card-border-hover);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.5), 0 0 16px rgba(236, 72, 153, 0.15);
}

/* Thumbnail Section */
.card-thumbnail-wrapper {
  position: relative;
  width: 100%;
  padding-top: 56.25%; /* 16:9 Aspect Ratio */
  background: #000;
  overflow: hidden;
}

.card-thumbnail-img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.lecture-card:hover .card-thumbnail-img {
  transform: scale(1.05);
}

/* Thumbnail Badges & Overlays */
.badge-number {
  position: absolute;
  top: 10px;
  left: 10px;
  background: rgba(15, 10, 28, 0.85);
  border: 1px solid var(--badge-border);
  color: var(--badge-text);
  font-family: 'Outfit', sans-serif;
  font-weight: 700;
  font-size: 0.78rem;
  padding: 3px 9px;
  border-radius: 8px;
  backdrop-filter: blur(8px);
  box-shadow: 0 2px 8px rgba(0,0,0,0.4);
}

.badge-duration {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: rgba(0, 0, 0, 0.82);
  color: #fff;
  font-size: 0.72rem;
  font-weight: 500;
  padding: 3px 7px;
  border-radius: 4px;
}

.play-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.35);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.lecture-card:hover .play-overlay, .lecture-card:active .play-overlay {
  opacity: 1;
}

.play-icon-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-glow), var(--secondary-glow));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  box-shadow: 0 0 16px rgba(236, 72, 153, 0.6);
  transform: scale(0.9);
  transition: transform var(--transition-fast);
}

.lecture-card:hover .play-icon-btn {
  transform: scale(1);
}

/* Card Content Area */
.card-content {
  padding: 16px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.card-title {
  font-size: 0.98rem;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: 4px;
  color: #ffffff;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-title-jp {
  font-size: 0.76rem;
  color: var(--text-dim);
  margin-bottom: 10px;
}

.card-summary {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 12px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.5;
}

.card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: auto;
}

.tag-pill {
  font-size: 0.7rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.06);
  color: var(--text-muted);
  padding: 2px 7px;
  border-radius: 10px;
}

/* Mobile Optimized Modal Popup Player */
.modal-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(6, 3, 14, 0.88);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-smooth);
  padding: 16px;
}

.modal-backdrop.active {
  opacity: 1;
  pointer-events: auto;
}

.modal-window {
  width: 100%;
  max-width: 1100px;
  max-height: 92vh;
  background: rgba(21, 14, 35, 0.96);
  border: 1px solid rgba(236, 72, 153, 0.3);
  border-radius: 20px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.9), 0 0 30px rgba(139, 92, 246, 0.2);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transform: scale(0.95);
  transition: transform var(--transition-smooth);
}

.modal-backdrop.active .modal-window {
  transform: scale(1);
}

.modal-header {
  padding: 14px 20px;
  border-bottom: 1px solid var(--card-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(15, 10, 28, 0.95);
  flex-shrink: 0;
}

.modal-title-group h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: #fff;
  line-height: 1.3;
}

.modal-close-btn {
  background: rgba(255, 255, 255, 0.08);
  border: none;
  color: #fff;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  transition: var(--transition-fast);
  flex-shrink: 0;
  touch-action: manipulation;
}

.modal-close-btn:hover, .modal-close-btn:active {
  background: rgba(236, 72, 153, 0.3);
}

.modal-body {
  display: grid;
  grid-template-columns: 1.5fr 1fr;
  flex-grow: 1;
  overflow: hidden;
}

.modal-player-section {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  background: rgba(10, 6, 18, 0.6);
  border-right: 1px solid var(--card-border);
  overflow-y: auto;
}

.iframe-container {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #000;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.6);
  flex-shrink: 0;
}

.iframe-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

.modal-transcript-section {
  padding: 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 18px;
  background: rgba(18, 12, 30, 0.4);
  -webkit-overflow-scrolling: touch;
}

.section-label {
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--badge-text);
  margin-bottom: 8px;
}

.timestamp-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.timestamp-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--card-border);
  border-radius: 8px;
  cursor: pointer;
  transition: var(--transition-fast);
  touch-action: manipulation;
  min-height: 44px;
}

.timestamp-item:hover, .timestamp-item:active {
  background: rgba(139, 92, 246, 0.18);
  border-color: var(--secondary-glow);
}

.timestamp-time {
  font-family: 'Outfit', sans-serif;
  font-weight: 600;
  color: var(--accent-cyan);
  font-size: 0.82rem;
  background: rgba(6, 182, 212, 0.12);
  padding: 3px 8px;
  border-radius: 6px;
  flex-shrink: 0;
}

.timestamp-desc {
  font-size: 0.83rem;
  color: var(--text-main);
  line-height: 1.4;
}

.transcript-text {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.75;
  white-space: pre-line;
  background: rgba(255, 255, 255, 0.02);
  padding: 14px;
  border-radius: 10px;
  border: 1px solid var(--card-border);
}

/* Mobile Layout Media Queries */
@media (max-width: 900px) {
  .header-inner {
    flex-wrap: wrap;
  }
  
  .search-box {
    width: 100%;
  }

  .modal-backdrop {
    padding: 10px;
  }

  .modal-window {
    max-height: 95vh;
    border-radius: 16px;
  }

  .modal-body {
    grid-template-columns: 1fr;
    overflow-y: auto;
  }

  .modal-player-section {
    border-right: none;
    border-bottom: 1px solid var(--card-border);
    padding: 16px;
  }

  .modal-transcript-section {
    padding: 16px;
  }
}

@media (max-width: 480px) {
  .logo-text-group h1 {
    font-size: 1rem;
  }
  .hero-banner h2 {
    font-size: 1.45rem;
  }
  .hero-banner p {
    font-size: 0.85rem;
  }
  .app-container {
    padding: 0 12px 60px 12px;
  }
}

/* Loading & Empty State */
.loading-trigger {
  text-align: center;
  padding: 36px 0;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.pulse-dots {
  display: inline-flex;
  gap: 6px;
}

.pulse-dot {
  width: 8px;
  height: 8px;
  background: var(--primary-glow);
  border-radius: 50%;
  animation: pulse 1.4s infinite ease-in-out both;
}

.pulse-dot:nth-child(1) { animation-delay: -0.32s; }
.pulse-dot:nth-child(2) { animation-delay: -0.16s; }

@keyframes pulse {
  0%, 80%, 100% { transform: scale(0); opacity: 0.3; }
  40% { transform: scale(1); opacity: 1; }
}

/* Footer */
.site-footer {
  text-align: center;
  padding: 30px 16px;
  color: var(--text-dim);
  font-size: 0.8rem;
  border-top: 1px solid var(--card-border);
  margin-top: 40px;
}