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

:root {
  --orange: #ff6b00;
  --orange-hover: #ff8a33;
  --orange-dim: #ff6b0020;
  --black: #0a0a0a;
  --dark: #111111;
  --dark-2: #1a1a1a;
  --dark-3: #222222;
  --dark-4: #2a2a2a;
  --gray: #888888;
  --light: #e0e0e0;
  --white: #f5f5f5;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--black);
  color: var(--white);
  line-height: 1.6;
}

/* ===== Gate Page ===== */
.gate-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}

.gate-container {
  text-align: center;
  background: var(--dark-2);
  padding: 3rem 2.5rem;
  border-radius: 16px;
  border: 1px solid var(--dark-3);
  width: 90%;
  max-width: 400px;
}

.gate-logo {
  font-size: 3rem;
  color: var(--orange);
  margin-bottom: 1rem;
}

.gate-container h1 {
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
}

.gate-container p {
  color: var(--gray);
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
}

.gate-container input {
  width: 100%;
  padding: 0.85rem 1rem;
  border: 1px solid var(--dark-4);
  border-radius: 10px;
  background: var(--dark);
  color: var(--white);
  font-size: 1rem;
  outline: none;
  margin-bottom: 1rem;
  transition: border-color 0.2s;
}

.gate-container input:focus {
  border-color: var(--orange);
}

.gate-container button {
  width: 100%;
  padding: 0.85rem;
  background: var(--orange);
  color: var(--black);
  border: none;
  border-radius: 10px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.gate-container button:hover {
  background: var(--orange-hover);
}

.error-msg {
  color: #ff4444;
  margin-top: 1rem;
  font-size: 0.9rem;
}

/* ===== Course Layout ===== */
.course-layout {
  display: flex;
  min-height: 100vh;
}

/* ===== Sidebar ===== */
.sidebar {
  width: 300px;
  background: var(--dark);
  border-right: 1px solid var(--dark-3);
  padding: 1.5rem 0;
  overflow-y: auto;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 10;
  transition: transform 0.3s ease;
}

.sidebar-header {
  padding: 0 1.5rem 1.5rem;
  border-bottom: 1px solid var(--dark-3);
  margin-bottom: 1rem;
}

.sidebar-logo {
  width: 100%;
  max-width: 200px;
  height: auto;
}

.sidebar-header .progress-text {
  font-size: 0.8rem;
  color: var(--gray);
  margin-top: 0.25rem;
}

.progress-bar {
  width: 100%;
  height: 4px;
  background: var(--dark-3);
  border-radius: 2px;
  margin-top: 0.75rem;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--orange);
  border-radius: 2px;
  transition: width 0.3s ease;
}

.module-list {
  list-style: none;
}

.section-header {
  padding: 1rem 1.5rem 0.4rem;
  font-size: 0.95rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--orange);
  border-top: 1px solid var(--dark-3);
  margin-top: 0.5rem;
}

.section-header:first-child {
  border-top: none;
  margin-top: 0;
}

.module-item {
  padding: 0.75rem 1.5rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.9rem;
  color: var(--gray);
  transition: all 0.15s;
  border-left: 3px solid transparent;
}

.module-item:hover {
  background: var(--dark-2);
  color: var(--light);
}

.module-item.active {
  background: var(--orange-dim);
  color: var(--orange);
  border-left-color: var(--orange);
}

.module-item.completed {
  color: var(--light);
}

.module-check {
  width: 20px;
  height: 20px;
  border: 2px solid var(--dark-4);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 0.7rem;
}

.module-item.completed .module-check {
  background: var(--orange);
  border-color: var(--orange);
  color: var(--black);
}

/* ===== Main Content ===== */
.main-content {
  flex: 1;
  margin-left: 300px;
  padding: 2rem 3rem;
  max-width: 900px;
}

.lesson-header {
  margin-bottom: 2rem;
}

.lesson-tag {
  display: inline-block;
  background: var(--orange-dim);
  color: var(--orange);
  padding: 0.3rem 0.75rem;
  border-radius: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.lesson-header h1 {
  font-size: 1.8rem;
  line-height: 1.3;
}

.video-container {
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--dark-2);
  border-radius: 12px;
  border: 1px solid var(--dark-3);
  overflow: hidden;
  margin-bottom: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.video-container iframe {
  width: 100%;
  height: 100%;
  border: none;
}

.video-placeholder {
  text-align: center;
  color: var(--gray);
}

.video-placeholder .play-icon {
  font-size: 3rem;
  color: var(--orange);
  margin-bottom: 0.5rem;
}

.video-placeholder p {
  font-size: 0.9rem;
}

.lesson-description {
  background: var(--dark-2);
  border-radius: 12px;
  padding: 1.5rem;
  border: 1px solid var(--dark-3);
  margin-bottom: 2rem;
  color: var(--light);
  font-size: 0.95rem;
}

.lesson-description h3 {
  color: var(--white);
  margin-bottom: 0.75rem;
}

.lesson-description a {
  color: var(--orange);
  text-decoration: none;
  font-weight: 600;
}

.lesson-description a:hover {
  text-decoration: underline;
  color: var(--orange-hover);
}

/* ===== Navigation Buttons ===== */
.lesson-nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--dark-3);
}

.nav-btn {
  padding: 0.75rem 1.5rem;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
}

.nav-btn.prev {
  background: var(--dark-2);
  color: var(--light);
  border: 1px solid var(--dark-4);
}

.nav-btn.prev:hover {
  background: var(--dark-3);
}

.nav-btn.next {
  background: var(--orange);
  color: var(--black);
}

.nav-btn.next:hover {
  background: var(--orange-hover);
}

.nav-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.mark-complete-btn {
  padding: 0.75rem 1.5rem;
  background: transparent;
  color: var(--orange);
  border: 2px solid var(--orange);
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.mark-complete-btn:hover {
  background: var(--orange);
  color: var(--black);
}

.mark-complete-btn.is-completed {
  background: var(--orange);
  color: var(--black);
}

/* ===== Mobile Menu Toggle ===== */
.menu-toggle {
  display: none;
  position: fixed;
  top: 1rem;
  left: 1rem;
  z-index: 20;
  background: var(--dark-2);
  border: 1px solid var(--dark-3);
  color: var(--orange);
  font-size: 1.5rem;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  cursor: pointer;
  line-height: 1;
}

/* ===== Mobile ===== */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
    width: 280px;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    padding: 1.5rem 1.25rem;
    padding-top: 4rem;
  }

  .menu-toggle {
    display: block;
  }

  .lesson-header h1 {
    font-size: 1.4rem;
  }

  .lesson-nav {
    flex-direction: column;
  }

  .nav-btn, .mark-complete-btn {
    width: 100%;
    text-align: center;
  }
}

/* Overlay for mobile sidebar */
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 5;
}

.sidebar-overlay.active {
  display: block;
}