/* ================================================================
   Course View Layout — Sidebar + Content (Agentic AI format)
   ================================================================ */

.course-app {
  display: flex;
  min-height: 100vh;
  background: var(--bg);
}

/* ── Sidebar ── */
.course-sidebar {
  width: 320px;
  min-width: 280px;
  max-width: 360px;
  background: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 100;
  overflow: hidden;
  transition: width .25s cubic-bezier(.4,0,.2,1), min-width .25s cubic-bezier(.4,0,.2,1);
}

/* Collapse arrow button — lives outside sidebar to avoid overflow clipping */
.sidebar-collapse-btn {
  position: fixed;
  top: 14px;
  left: 306px;
  z-index: 110;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  font-size: 1rem;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all .25s cubic-bezier(.4,0,.2,1);
  box-shadow: 0 1px 4px rgba(0,0,0,.1);
}
.sidebar-collapse-btn:hover {
  background: var(--surface2);
  color: var(--primary);
}

/* Collapsed sidebar state */
.course-sidebar.collapsed-sidebar {
  width: 0;
  min-width: 0;
  border-right: none;
}

/* Expand button when sidebar is collapsed — uses direct class from JS */
.sidebar-collapse-btn.is-collapsed {
  left: 12px;
  top: 50%;
  transform: translateY(-50%) rotate(180deg);
  width: 40px;
  height: 40px;
  font-size: 1.3rem;
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
  box-shadow: 0 2px 12px rgba(0,0,0,.2);
}
.sidebar-collapse-btn.is-collapsed:hover {
  background: color-mix(in srgb, var(--primary) 85%, black);
  color: #fff;
  transform: translateY(-50%) rotate(180deg) scale(1.1);
}
.course-sidebar.collapsed-sidebar .course-sidebar-header,
.course-sidebar.collapsed-sidebar .course-search-wrap,
.course-sidebar.collapsed-sidebar .course-parts {
  opacity: 0;
  pointer-events: none;
  transition: opacity .15s;
}

.course-sidebar-header {
  padding: 20px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.course-sidebar-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 6px;
  font-family: 'Source Sans 3', system-ui, sans-serif;
}

.course-progress-text {
  font-size: .78rem;
  color: var(--muted);
  font-weight: 600;
}

.course-progress-bar {
  height: 6px;
  background: var(--surface2);
  border-radius: 3px;
  margin-top: 10px;
  overflow: hidden;
}

.course-progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 3px;
  transition: width .6s cubic-bezier(.4,0,.2,1);
}

.course-search-wrap {
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
  position: relative;
}

.course-search-input {
  width: 100%;
  padding: 10px 14px 10px 36px;
  font-size: .85rem;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface2);
  color: var(--text);
  font-family: inherit;
  transition: border-color .2s, box-shadow .2s;
}

.course-search-input::placeholder {
  color: var(--muted);
}

.course-search-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 15%, transparent);
}

.course-search-icon {
  position: absolute;
  left: 26px;
  top: 50%;
  transform: translateY(-50%);
  font-size: .9rem;
  color: var(--muted);
  pointer-events: none;
}

.course-search-count {
  position: absolute;
  right: 26px;
  top: 50%;
  transform: translateY(-50%);
  font-size: .7rem;
  color: var(--muted);
  font-weight: 600;
  pointer-events: none;
}

.course-parts {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0 24px;
  scroll-behavior: smooth;
}

/* Custom scrollbar */
.course-parts::-webkit-scrollbar {
  width: 5px;
}
.course-parts::-webkit-scrollbar-track {
  background: transparent;
}
.course-parts::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}
.course-parts::-webkit-scrollbar-thumb:hover {
  background: var(--muted);
}

.course-part {
  margin-bottom: 4px;
}

.course-part.hidden {
  display: none;
}

.course-part-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
  transition: background .2s, color .2s;
}

.course-part-header:hover {
  background: var(--surface2);
}

.course-part-header.active {
  color: var(--primary);
}

.course-part-title {
  display: flex;
  align-items: center;
  gap: 6px;
  min-width: 0;
}

/* Chevron indicator for collapse/expand */
.course-part-chevron {
  display: inline-block;
  width: 0;
  height: 0;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 5px solid currentColor;
  transition: transform .2s ease;
  flex-shrink: 0;
}

.course-part.collapsed .course-part-chevron {
  transform: rotate(-90deg);
}

.course-part-progress {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.course-part-count {
  font-size: .7rem;
  color: var(--muted);
  font-weight: 600;
}

/* Mini progress ring per module */
.course-part-ring {
  --ring-size: 18px;
  --ring-width: 2.5px;
  --ring-pct: 0;
  --ring-color: var(--primary);
  width: var(--ring-size);
  height: var(--ring-size);
  border-radius: 50%;
  background: conic-gradient(
    var(--ring-color) calc(var(--ring-pct) * 3.6deg),
    var(--surface2) calc(var(--ring-pct) * 3.6deg)
  );
  position: relative;
  flex-shrink: 0;
}
.course-part-ring::after {
  content: '';
  position: absolute;
  inset: var(--ring-width);
  border-radius: 50%;
  background: var(--surface);
}

.course-lessons {
  padding-left: 8px;
  overflow: hidden;
  transition: max-height .25s ease;
}

.course-part.collapsed .course-lessons {
  display: none;
}

.course-lesson {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 16px 10px 12px;
  font-size: .85rem;
  color: var(--text);
  text-decoration: none;
  cursor: pointer;
  transition: background .15s, color .15s, border-color .15s;
  border-left: 3px solid transparent;
}

.course-lesson:hover {
  background: var(--surface2);
}

.course-lesson.current {
  background: color-mix(in srgb, var(--primary) 12%, transparent);
  border-left-color: var(--primary);
  color: var(--primary);
  font-weight: 600;
}

.course-lesson.completed .lesson-title {
  color: var(--muted);
}

.course-lesson.completed.current .lesson-title {
  color: var(--primary);
}

.lesson-icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .75rem;
  border-radius: 50%;
  border: 2px solid var(--border);
  color: var(--muted);
  transition: all .2s;
  margin-top: 1px;
}

.course-lesson.completed .lesson-icon {
  border-color: var(--primary);
  color: var(--primary);
  background: color-mix(in srgb, var(--primary) 15%, transparent);
}

.course-lesson.completed .lesson-icon::before {
  content: '\2713';
  font-weight: 700;
}

.course-lesson.current:not(.completed) .lesson-icon {
  border-color: var(--primary);
  color: var(--primary);
  background: transparent;
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 15%, transparent);
}

.lesson-content {
  flex: 1;
  min-width: 0;
}

.lesson-title {
  display: block;
  line-height: 1.4;
  word-break: break-word;
}

.lesson-meta {
  font-size: .7rem;
  color: var(--muted);
  margin-top: 2px;
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
}

/* Difficulty badges */
.lesson-diff {
  display: inline-block;
  padding: 1px 6px;
  border-radius: 3px;
  font-size: .62rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .03em;
}
.lesson-diff[class] { /* foundational default */
  background: color-mix(in srgb, #2e7d32 15%, transparent);
  color: #2e7d32;
}
[data-theme="dark"] .lesson-diff[class] {
  background: color-mix(in srgb, #66bb6a 20%, transparent);
  color: #66bb6a;
}

.course-lesson.diff-intermediate .lesson-diff {
  background: color-mix(in srgb, #b8860b 15%, transparent);
  color: #b8860b;
}
[data-theme="dark"] .course-lesson.diff-intermediate .lesson-diff {
  background: color-mix(in srgb, #e6b800 20%, transparent);
  color: #e6b800;
}

.course-lesson.diff-advanced .lesson-diff {
  background: color-mix(in srgb, #c62828 12%, transparent);
  color: #c62828;
}
[data-theme="dark"] .course-lesson.diff-advanced .lesson-diff {
  background: color-mix(in srgb, #ef5350 20%, transparent);
  color: #ef5350;
}

.course-lesson.hidden {
  display: none;
}

/* ── Main Content ── */
.course-main {
  flex: 1;
  margin-left: 320px;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  transition: margin-left .25s cubic-bezier(.4,0,.2,1);
}

.course-sidebar.collapsed-sidebar ~ .course-main {
  margin-left: 0;
}

.course-content-frame {
  flex: 1;
  width: 100%;
  border: none;
  background: var(--surface);
  opacity: 1;
  transition: opacity .2s ease;
}

/* Loading state: fade iframe while loading */
.course-content-frame.loading {
  opacity: 0.3;
}

.course-content-placeholder {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 60px 40px;
  background: var(--surface);
  color: var(--muted);
  text-align: center;
}

.course-content-placeholder h2 {
  font-size: 1.6rem;
  color: var(--text);
  margin-bottom: 12px;
  font-family: 'Source Sans 3', system-ui, sans-serif;
}

.course-content-placeholder p {
  font-size: .95rem;
  max-width: 400px;
}

.placeholder-welcome {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.course-resume-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  margin-top: 16px;
  font-size: 1rem;
  font-weight: 700;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-family: 'Source Sans 3', system-ui, sans-serif;
  transition: background .2s, transform .1s, box-shadow .2s;
  box-shadow: 0 2px 8px color-mix(in srgb, var(--primary) 30%, transparent);
}

.course-resume-btn:hover {
  background: color-mix(in srgb, var(--primary) 85%, black);
  box-shadow: 0 4px 16px color-mix(in srgb, var(--primary) 40%, transparent);
  transform: translateY(-1px);
}

.course-resume-btn:active {
  transform: translateY(0) scale(0.98);
}

.placeholder-hint {
  font-size: .8rem !important;
  color: var(--muted) !important;
  margin-top: 8px !important;
}

/* ── Bottom Bar (Complete & Continue) ── */
.course-bottom-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
  background: var(--surface);
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}

.course-bottom-bar.hidden {
  display: none;
}

.course-complete-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  font-size: .9rem;
  font-weight: 700;
  color: #fff;
  background: var(--primary);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-family: inherit;
  transition: background .2s, transform .1s, box-shadow .2s;
  box-shadow: 0 2px 6px color-mix(in srgb, var(--primary) 25%, transparent);
}

.course-complete-btn:hover {
  background: color-mix(in srgb, var(--primary) 85%, black);
  box-shadow: 0 3px 10px color-mix(in srgb, var(--primary) 35%, transparent);
}

.course-complete-btn:active {
  transform: scale(0.98);
}

.course-complete-btn:disabled {
  opacity: .6;
  cursor: not-allowed;
}

.course-nav-links {
  display: flex;
  gap: 8px;
  align-items: center;
}

.course-nav-links a {
  font-size: .82rem;
  font-weight: 600;
  color: var(--muted);
  text-decoration: none;
  padding: 6px 14px;
  border-radius: 6px;
  border: 1px solid var(--border);
  transition: all .2s;
}

.course-nav-links a:hover {
  color: var(--primary);
  border-color: var(--primary);
  background: color-mix(in srgb, var(--primary) 8%, transparent);
}

/* Keyboard hint in bottom bar */
.course-kbd-hint {
  font-size: .7rem;
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 4px;
}
.course-kbd-hint kbd {
  display: inline-block;
  padding: 1px 5px;
  font-size: .65rem;
  font-family: inherit;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 3px;
}

/* ── Top Bar (for course view) ── */
.course-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 24px;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.course-top-bar a {
  font-size: .82rem;
  font-weight: 600;
  color: var(--primary);
  text-decoration: none;
  transition: opacity .2s;
}

.course-top-bar a:hover {
  opacity: .8;
}

.course-current-title {
  flex: 1;
  text-align: center;
  font-size: .82rem;
  font-weight: 600;
  color: var(--text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  padding: 0 16px;
  font-family: 'Source Sans 3', system-ui, sans-serif;
}

.course-top-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

/* ── Responsive ── */
@media (max-width: 900px) {
  .course-sidebar {
    width: 280px;
  }

  .course-main {
    margin-left: 280px;
  }

  .sidebar-collapse-btn {
    left: 266px;
  }

  .course-sidebar.collapsed-sidebar ~ .course-main {
    margin-left: 0;
  }

  .sidebar-collapse-btn.is-collapsed {
    left: 4px;
  }
}

.sidebar-toggle {
  display: none;
  position: fixed;
  bottom: 80px;
  left: 12px;
  z-index: 101;
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: var(--primary);
  color: #fff;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0,0,0,.2);
  transition: transform .2s;
}

.sidebar-toggle:active {
  transform: scale(0.92);
}

/* Mobile overlay backdrop */
@media (max-width: 768px) {
  .sidebar-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .course-sidebar {
    transform: translateX(-100%);
    transition: transform .3s cubic-bezier(.4,0,.2,1);
    box-shadow: none;
  }

  .course-sidebar.open {
    transform: translateX(0);
    box-shadow: 4px 0 24px rgba(0,0,0,.15);
  }

  .course-main {
    margin-left: 0;
  }

  .course-bottom-bar {
    flex-direction: column;
    gap: 10px;
    align-items: stretch;
  }

  .course-nav-links {
    justify-content: space-between;
  }

  .course-kbd-hint {
    display: none;
  }

  .course-top-actions {
    display: none;
  }

  .sidebar-collapse-btn {
    display: none;
  }
}