:root {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #182234;
  --bg-elevated: #334155;
  --border-color: #334155;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --accent-color: #38bdf8;
  --accent-hover: #0284c7;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --zalo-color: #0068ff;
  --tele-color: #24A1DE;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* HEADER */
.app-header {
  background-color: rgba(30, 41, 59, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.brand-logo {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, #d97706, #d946ef);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: bold;
}

.brand-title {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand-subtitle {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

/* SOCIAL PILLS */
.btn-social {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.45rem 0.9rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  color: #fff;
  transition: transform 0.15s ease, opacity 0.15s ease;
}

.btn-social:hover {
  transform: translateY(-1px);
  opacity: 0.95;
}

.btn-zalo {
  background-color: var(--zalo-color);
}

.btn-telegram {
  background-color: var(--tele-color);
}

.btn-api {
  background: linear-gradient(135deg, #ec4899, #8b5cf6);
  color: #fff;
  box-shadow: 0 2px 10px rgba(236, 72, 153, 0.35);
  animation: pulse-api 2.5s infinite;
}

@keyframes pulse-api {
  0%, 100% {
    box-shadow: 0 2px 10px rgba(236, 72, 153, 0.35);
  }
  50% {
    box-shadow: 0 4px 18px rgba(139, 92, 246, 0.6);
  }
}

.btn-social svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

/* USER AUTH BAR */
.auth-container {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-google {
  background-color: #ffffff;
  color: #1f2937;
  border: none;
  border-radius: 8px;
  padding: 0.5rem 1rem;
  font-size: 0.85rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  transition: background-color 0.15s ease;
}

.btn-google:hover {
  background-color: #f1f5f9;
}

.user-profile {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  padding: 0.3rem 0.75rem;
  border-radius: 30px;
}

.user-avatar {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
  color: #0f172a;
  overflow: hidden;
}

.user-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.user-info {
  display: flex;
  flex-direction: column;
}

.user-name {
  font-size: 0.85rem;
  font-weight: 600;
  line-height: 1.2;
}

.user-badge {
  font-size: 0.7rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.badge-approved {
  color: var(--success-color);
}

.badge-unapproved {
  color: var(--warning-color);
}

.btn-logout {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  font-size: 0.75rem;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

.btn-logout:hover {
  color: var(--danger-color);
}

/* MAIN LAYOUT */
.main-wrapper {
  display: grid;
  grid-template-columns: 1fr 360px;
  gap: 1.5rem;
  padding: 1.5rem;
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
  flex: 1;
}

@media (max-width: 1024px) {
  .main-wrapper {
    grid-template-columns: 1fr;
  }
}

/* VIDEO STAGE */
.stage-container {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.player-wrapper {
  background-color: #000;
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
  aspect-ratio: 16 / 9;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
  border: 1px solid var(--border-color);
  user-select: none;
  -webkit-user-select: none;
}

/* CHỐNG TẢI VIDEO TRIỆT ĐỂ */
video::-internal-media-controls-download-button {
  display: none !important;
}

video::-webkit-media-controls-download-button {
  display: none !important;
}

.player-wrapper video {
  width: 100%;
  height: 100%;
  object-fit: contain;
  background-color: #000;
}

/* LOCK OVERLAY */
.lock-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(15, 23, 42, 0.95), rgba(30, 41, 59, 0.95));
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  text-align: center;
  z-index: 10;
}

.lock-icon-circle {
  width: 64px;
  height: 64px;
  background-color: rgba(239, 68, 68, 0.15);
  border: 2px solid var(--danger-color);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1rem;
  color: var(--danger-color);
  font-size: 1.75rem;
}

.lock-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.lock-desc {
  color: var(--text-muted);
  max-width: 520px;
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
}

.lock-cta-group {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
  justify-content: center;
}

.btn-cta {
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  cursor: pointer;
  border: none;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-cta-primary {
  background-color: var(--accent-color);
  color: #0f172a;
}

.btn-cta-primary:hover {
  background-color: var(--accent-hover);
}

/* LESSON INFO */
.lesson-meta-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
}

.lesson-meta-top {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.badge-tag {
  background-color: var(--accent-color);
  color: #0f172a;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
}

.badge-free {
  background-color: var(--success-color);
  color: #fff;
}

.lesson-duration {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.lesson-active-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.lesson-active-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
}

/* TABS CONTAINER */
.tabs-container {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.tabs-nav {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  background-color: var(--bg-card);
}

.tab-btn {
  padding: 1rem 1.5rem;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  border-bottom: 2px solid transparent;
  transition: all 0.2s ease;
}

.tab-btn:hover {
  color: var(--text-main);
}

.tab-btn.active {
  color: var(--accent-color);
  border-bottom-color: var(--accent-color);
  background-color: rgba(56, 189, 248, 0.05);
}

.tab-pane {
  display: none;
  padding: 1.75rem;
}

.tab-pane.active {
  display: block;
}

/* SIDEBAR CURRICULUM */
.sidebar-container {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.curriculum-card {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.curriculum-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1rem;
  font-weight: 700;
}

.progress-bar-container {
  background-color: var(--bg-elevated);
  height: 6px;
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar-fill {
  background-color: var(--success-color);
  height: 100%;
  width: 25%;
  transition: width 0.3s ease;
}

.lesson-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.lesson-item {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 0.85rem 1rem;
  cursor: pointer;
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  transition: all 0.15s ease;
}

.lesson-item:hover {
  border-color: var(--accent-color);
  background-color: rgba(56, 189, 248, 0.05);
}

.lesson-item.active {
  border-color: var(--accent-color);
  background-color: rgba(56, 189, 248, 0.12);
}

.lesson-item-icon {
  font-size: 1.1rem;
  margin-top: 2px;
}

.lesson-item-body {
  flex: 1;
}

.lesson-item-title {
  font-size: 0.9rem;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 0.25rem;
}

.lesson-item-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* SIDEBAR SUPPORT BOX */
.sidebar-support {
  background: linear-gradient(135deg, rgba(30, 41, 59, 0.9), rgba(15, 23, 42, 0.9));
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  text-align: center;
}

.sidebar-support h4 {
  font-size: 1rem;
  margin-bottom: 0.5rem;
}

.sidebar-support p {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.sidebar-support .social-stack {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

/* DOCS STYLING */
.doc-content h2, .doc-content h3, .doc-content h4 {
  margin: 1.25rem 0 0.75rem;
  color: var(--text-main);
}

.doc-content h2 {
  font-size: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.5rem;
}

.doc-content p {
  margin-bottom: 0.85rem;
  color: #cbd5e1;
}

.styled-list {
  padding-left: 1.25rem;
  margin-bottom: 1rem;
  color: #cbd5e1;
}

.styled-list li {
  margin-bottom: 0.4rem;
}

.callout {
  padding: 1rem 1.25rem;
  border-radius: var(--radius-sm);
  margin: 1rem 0;
  border-left: 4px solid;
}

.callout-info {
  background-color: rgba(56, 189, 248, 0.1);
  border-left-color: var(--accent-color);
}

.callout-success {
  background-color: rgba(16, 185, 129, 0.1);
  border-left-color: var(--success-color);
}

.grid-2, .grid-3 {
  display: grid;
  gap: 1rem;
  margin: 1rem 0;
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); }

.card-feature, .sub-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 1rem;
}

.custom-table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}

.custom-table th, .custom-table td {
  border: 1px solid var(--border-color);
  padding: 0.75rem 1rem;
  text-align: left;
}

.custom-table th {
  background-color: var(--bg-elevated);
}

.prompt-comparison {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 1rem 0;
}

@media (max-width: 600px) {
  .prompt-comparison {
    grid-template-columns: 1fr;
  }
}

.prompt-bad {
  background-color: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.3);
  padding: 1rem;
  border-radius: var(--radius-sm);
}

.prompt-good {
  background-color: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.3);
  padding: 1rem;
  border-radius: var(--radius-sm);
}

.prompt-bad .label { color: var(--danger-color); font-weight: bold; }
.prompt-good .label { color: var(--success-color); font-weight: bold; }

.quote-box {
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.1), rgba(217, 70, 239, 0.1));
  border: 1px solid var(--accent-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-top: 1.5rem;
}

.pill {
  background-color: var(--accent-color);
  color: #0f172a;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 700;
}

/* MODAL */
.modal-backdrop {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}

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

.modal-dialog {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 90%;
  max-width: 440px;
  padding: 2rem;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5);
  position: relative;
}

.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 1.25rem;
  cursor: pointer;
}

.modal-title {
  font-size: 1.2rem;
  margin-bottom: 0.5rem;
}

.modal-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

.form-group {
  margin-bottom: 1rem;
}

.form-input {
  width: 100%;
  padding: 0.75rem 1rem;
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  font-size: 0.9rem;
}

.form-input:focus {
  outline: none;
  border-color: var(--accent-color);
}