/* Lecture viewer styles (from Lessons) */
.culture-panel.hidden {
  display: none;
}

.lecture-card {
  padding: 0.25rem 0;
}

.lecture-title {
  margin: 0 0 0.2rem;
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--navy);
}

.lecture-subtitle {
  margin: 0 0 0.35rem;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.lecture-grammar {
  margin: 0 0 0.5rem;
  font-size: 0.82rem;
  color: var(--navy);
}

.lecture-guide {
  margin: 0 0 0.85rem;
  font-size: 0.88rem;
  line-height: 1.5;
  color: var(--text);
}

.lecture-sections {
  margin: 0 0 0.85rem;
}

.lecture-sections ul {
  margin: 0.35rem 0 0;
  padding-left: 1.1rem;
  font-size: 0.82rem;
  color: var(--text-muted);
  line-height: 1.45;
}

.lecture-card-header {
  margin-bottom: 0.75rem;
}

.lecture-viewer-wrap {
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: #f0eeea;
}

.lecture-slide-viewer {
  display: flex;
  flex-direction: column;
}

.lecture-slide-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  flex-wrap: wrap;
  padding: 0.55rem 0.75rem;
  background: var(--surface);
  border-bottom: 1.5px solid var(--border);
}

.lecture-slide-expand {
  margin-left: auto;
  padding: 0.4rem 0.75rem;
  font-size: 0.78rem;
  font-weight: 700;
  color: #fff;
  background: var(--red);
  border: 0;
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.lecture-slide-expand:hover {
  opacity: 0.92;
}

.lecture-slide-img-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: zoom-in;
}

.lecture-slide-nav {
  display: inline-flex;
  align-items: center;
  gap: 0.2rem;
  padding: 0.4rem 0.75rem;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--navy);
  background: var(--cream, #f7f5f0);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}

.lecture-slide-nav:hover:not(:disabled) {
  border-color: var(--red);
  color: var(--red);
}

.lecture-slide-nav:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.lecture-slide-count {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--navy);
  min-width: 4.5rem;
  text-align: center;
}

.lecture-slide-stage {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: min(68vh, 520px);
  padding: 0.75rem;
  background: #e8e6e2;
  overflow: hidden;
}

.lecture-slide-frame {
  display: block;
  width: 100%;
  height: min(68vh, 560px);
  border: 0;
  background: #fff;
  border-radius: 4px;
  box-shadow: 0 4px 24px rgba(26, 35, 50, 0.12);
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.lecture-slide-frame--from-right {
  opacity: 0.35;
  transform: translateX(18px);
}

.lecture-slide-frame--from-left {
  opacity: 0.35;
  transform: translateX(-18px);
}

.lecture-slide-frame--settled {
  opacity: 1;
  transform: translateX(0);
}

.lecture-slide-img {
  display: block;
  max-width: 100%;
  max-height: min(68vh, 560px);
  width: auto;
  height: auto;
  margin: 0 auto;
  background: #fff;
  border-radius: 4px;
  box-shadow: 0 4px 24px rgba(26, 35, 50, 0.12);
  transition: opacity 0.25s ease, transform 0.25s ease;
}

.lecture-slide-img--from-right {
  opacity: 0.35;
  transform: translateX(18px);
}

.lecture-slide-img--from-left {
  opacity: 0.35;
  transform: translateX(-18px);
}

.lecture-slide-img--settled {
  opacity: 1;
  transform: translateX(0);
}

.lecture-slide-hint {
  margin: 0;
  padding: 0.5rem 0.75rem 0.65rem;
  font-size: 0.72rem;
  color: var(--text-muted);
  text-align: center;
  background: var(--surface);
  border-top: 1px solid var(--border);
}

/* PPT lightbox */
body.lecture-lightbox-open {
  overflow: hidden;
}

.lecture-lightbox {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.lecture-lightbox.hidden {
  display: none;
}

.lecture-lightbox-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(15, 22, 35, 0.82);
}

.lecture-lightbox-panel {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  width: min(96vw, 1100px);
  max-height: 96vh;
  background: #fff;
  border-radius: var(--radius-sm);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
  overflow: hidden;
}

.lecture-lightbox-close {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  z-index: 2;
  width: 2rem;
  height: 2rem;
  font-size: 1rem;
  line-height: 1;
  color: var(--navy);
  background: rgba(255, 255, 255, 0.9);
  border: 1.5px solid var(--border);
  border-radius: 50%;
  cursor: pointer;
}

.lecture-lightbox-close:hover {
  border-color: var(--red);
  color: var(--red);
}

.lecture-lightbox-toolbar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  padding: 0.65rem 2.5rem 0.55rem;
  background: var(--surface);
  border-bottom: 1.5px solid var(--border);
}

.lecture-lightbox-stage {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 1;
  min-height: 0;
  padding: 0.75rem;
  background: #e8e6e2;
  overflow: auto;
}

.lecture-lightbox-zoom-controls {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin-left: 0.5rem;
}

.lecture-zoom-btn,
.lecture-zoom-reset {
  min-width: 2.25rem;
  min-height: 2.25rem;
  padding: 0.25rem 0.5rem;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--navy);
  background: var(--cream, #f7f5f0);
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
}

.lecture-zoom-reset {
  font-size: 0.72rem;
  min-width: auto;
  padding: 0.35rem 0.55rem;
}

.lecture-zoom-btn:hover,
.lecture-zoom-reset:hover {
  border-color: var(--red);
  color: var(--red);
}

.lecture-zoom-label {
  min-width: 3rem;
  font-size: 0.75rem;
  font-weight: 700;
  text-align: center;
  color: var(--navy);
}

.lecture-lightbox-zoom-viewport {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  min-height: min(70vh, 560px);
  overflow: hidden;
  touch-action: none;
}

.lecture-lightbox-zoom-inner {
  transform-origin: center center;
  will-change: transform;
}

.lecture-lightbox-zoom-inner--animated {
  transition: transform 0.12s ease-out;
}

.lecture-lightbox-img {
  display: block;
  max-width: min(96vw, 1100px);
  max-height: calc(96vh - 140px);
  width: auto;
  height: auto;
  object-fit: contain;
  border-radius: 4px;
  box-shadow: 0 8px 32px rgba(26, 35, 50, 0.18);
  user-select: none;
  -webkit-user-drag: none;
}

/* Admin PPT upload */
.lecture-admin-panel {
  margin-bottom: 0.85rem;
  padding: 0.75rem 0.9rem;
  background: #fff8e8;
  border: 1.5px solid #e8c96a;
  border-radius: var(--radius-sm);
}

.lecture-admin-summary {
  font-size: 0.85rem;
  font-weight: 700;
  color: #8a5a00;
  cursor: pointer;
}