/* ==========================================================================
   SSB COURSE PLAYER - CLEAN, SPACIOUS & RESPONSIVE LMS STYLES
   ========================================================================== */

.player-body {
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: var(--bg-app);
  color: var(--text-main);
  height: 100vh;
  display: flex;
  flex-direction: column;
  font-family: var(--font-family);
}

.player-wrapper {
  display: flex;
  flex-direction: column;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
}

/* --- Top Navigation Header --- */
.player-header {
  height: 64px;
  background-color: var(--bg-header);
  border-bottom: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  flex-shrink: 0;
  z-index: 100;
  gap: 16px;
}

.player-header-left {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

/* Brand Logo */
.player-brand-logo {
  display: flex;
  align-items: center;
  flex-shrink: 0;
}

.player-brand-logo .brand-logo-img {
  width: 135px;
  height: auto;
}

.player-brand-logo .logo-light {
  display: block;
}

.player-brand-logo .logo-dark {
  display: none;
}

[data-theme="dark"] .player-brand-logo .logo-light {
  display: none !important;
}

[data-theme="dark"] .player-brand-logo .logo-dark {
  display: block !important;
}

.player-back-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--text-main);
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.player-back-btn:hover {
  background-color: var(--nav-hover-bg);
  border-color: var(--brand-blue);
  color: var(--brand-blue);
}

.player-divider {
  width: 1px;
  height: 22px;
  background-color: var(--border-light);
  flex-shrink: 0;
}

.player-course-meta-header {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
}

.player-course-badge {
  font-size: 11px;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background-color: var(--bg-card-subtle);
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-card);
  flex-shrink: 0;
}

.player-course-title {
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.player-header-right {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-shrink: 0;
}

.player-progress-widget {
  display: flex;
  flex-direction: column;
  gap: 3px;
  width: 130px;
}

.progress-labels {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 11px;
  font-weight: 600;
  color: var(--text-muted);
}

.progress-percent {
  color: var(--text-main);
  font-weight: 700;
}

.progress-track {
  width: 100%;
  height: 4px;
  background-color: var(--border-light);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background-color: var(--brand-blue);
  border-radius: 4px;
  transition: width 0.25s ease;
}

.player-icon-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  color: var(--text-main);
  transition: all var(--transition-fast);
}

.player-icon-btn:hover {
  background-color: var(--nav-hover-bg);
  color: var(--brand-blue);
}

.player-icon-btn svg {
  width: 18px;
  height: 18px;
}

/* Header thin progress bar */
.player-top-line {
  height: 2px;
  width: 100%;
  background-color: transparent;
  flex-shrink: 0;
}

.player-top-line-fill {
  height: 100%;
  background-color: var(--brand-blue);
  transition: width 0.25s ease;
}

/* --- Layout Grid (Spacious Area Distribution) --- */
.player-main-layout {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

/* --- Sidebar Syllabus (20-25% Width) --- */
.player-sidebar {
  width: 300px;
  background-color: var(--bg-sidebar);
  border-right: 1px solid var(--border-light);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  overflow-y: auto;
  z-index: 80;
  transition: transform 0.2s ease;
}

.sidebar-course-card {
  padding: 16px 18px;
  border-bottom: 1px solid var(--border-light);
  display: flex;
  gap: 12px;
  align-items: center;
  background-color: var(--bg-card-subtle);
}

.sidebar-thumb-wrap {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  overflow: hidden;
  flex-shrink: 0;
  border: 1px solid var(--border-light);
}

.sidebar-thumb-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.sidebar-course-details {
  flex: 1;
  min-width: 0;
}

.sidebar-course-name {
  font-size: var(--font-size-xs);
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.3;
}

.sidebar-course-desc {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 2px;
}

.syllabus-header {
  padding: 14px 18px 8px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.syllabus-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.syllabus-count {
  font-size: 11px;
  color: var(--text-muted);
}

.syllabus-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 0 10px 16px;
  flex: 1;
}

.syllabus-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  text-align: left;
  background-color: transparent;
  border: 1px solid transparent;
  transition: all var(--transition-fast);
  width: 100%;
}

.syllabus-item:hover {
  background-color: var(--nav-hover-bg);
}

.syllabus-item.active {
  background-color: var(--nav-active-bg);
  border-color: var(--border-card);
}

.syllabus-status-icon {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
  color: var(--text-subtle);
  position: relative;
}

.syllabus-status-icon .icon-circle {
  display: block;
}

.syllabus-status-icon .icon-check {
  display: none;
  color: #10b981;
}

.syllabus-item.completed .syllabus-status-icon .icon-circle {
  display: none;
}

.syllabus-item.completed .syllabus-status-icon .icon-check {
  display: block;
}

.syllabus-item.active .syllabus-status-icon .icon-circle {
  color: var(--brand-blue);
}

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

.syllabus-meta-row {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 2px;
}

.unit-type-pill {
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-muted);
}

.unit-duration {
  font-size: 11px;
  color: var(--text-subtle);
}

.syllabus-item-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-main);
  line-height: 1.35;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.syllabus-item.active .syllabus-item-title {
  color: var(--brand-blue);
  font-weight: 700;
}

.sidebar-footer-box {
  padding: 12px 16px;
  border-top: 1px solid var(--border-light);
  background-color: var(--bg-card-subtle);
}

.btn-reset-course {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  padding: 8px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-card);
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 600;
  transition: all var(--transition-fast);
}

.btn-reset-course:hover {
  background-color: var(--nav-hover-bg);
  color: #ef4444;
}

.btn-reset-course svg {
  width: 14px;
  height: 14px;
}
/* --- Viewport & Stage (Expansive 65-80% Page Area) --- */
.player-viewport {
  flex: 1;
  overflow-y: auto;
  position: relative;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-app);
  scroll-behavior: smooth;
  width: 100%;
}

.viewport-inner {
  flex: 1;
  max-width: 1140px;
  width: 92%;
  margin: 0 auto;
  padding: 36px 32px 110px;
}

/* Lesson Stage Smooth Transitions */
.lesson-stage {
  display: none;
  opacity: 0;
  transition: opacity 0.18s ease;
  width: 100%;
}

.lesson-stage.active {
  display: block;
  opacity: 1;
}

/* --- Clean Reader Typography --- */
.lesson-header-card {
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-light);
}

.lesson-meta-bar {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: var(--font-size-xs);
  color: var(--text-muted);
  margin-bottom: 8px;
}

.lesson-meta-bar .meta-dot {
  color: var(--text-subtle);
}

.lesson-main-title {
  font-size: 1.75rem;
  font-weight: 800;
  line-height: 1.3;
  color: var(--text-main);
  margin-bottom: 6px;
}

.lesson-lead-summary {
  font-size: 1.05rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.lesson-content-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 36px 40px 44px;
  width: 100%;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.02);
}

.content-body {
  font-size: var(--font-size-base);
  line-height: 1.8;
  color: var(--text-main);
}

.paragraph-text {
  margin-bottom: 20px;
  font-size: 1rem;
  line-height: 1.8;
}

.content-h2 {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-main);
  margin: 32px 0 16px;
}

.content-h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 22px 0 12px;
}

.content-list {
  margin: 14px 0 20px 24px;
  line-height: 1.8;
}

.content-list li {
  margin-bottom: 10px;
}

/* Simple Clean Callout */
.simple-callout {
  padding: 16px 20px;
  border-left: 3px solid var(--brand-blue);
  background-color: var(--bg-card-subtle);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 22px 0;
  font-size: var(--font-size-sm);
  line-height: 1.65;
}

.simple-callout.warning {
  border-left-color: #f59e0b;
}

.simple-callout.alert {
  border-left-color: #ef4444;
}

/* Simple 3 Dimensions Box (Responsive Grid) */
.dim-simple-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  margin: 22px 0;
}

.dim-simple-item {
  padding: 18px 20px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  display: flex;
  flex-direction: column;
}

.dim-simple-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.dim-simple-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-main);
}

.dim-simple-subtitle {
  font-size: 12px;
  color: var(--text-muted);
}

.dim-simple-body {
  font-size: var(--font-size-sm);
  line-height: 1.65;
  color: var(--text-main);
  flex: 1;
}

/* Simple Image Box */
.simple-image-box {
  margin: 24px 0;
  text-align: center;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  padding: 20px;
}

.simple-image-box img {
  max-height: 380px;
  margin: 0 auto 10px;
  object-fit: contain;
}

.simple-image-caption {
  font-size: var(--font-size-xs);
  color: var(--text-muted);
}

/* Case Study Clean Box */
.case-study-simple-box {
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  padding: 26px 28px;
  margin: 24px 0;
}

.case-study-heading {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-light);
}

.case-inventory-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0;
}

.case-tag {
  font-size: 12px;
  padding: 4px 12px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  color: var(--text-main);
}

.opinions-simple-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin: 16px 0;
}

.op-simple-item {
  padding: 14px 16px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  line-height: 1.55;
}

.op-simple-item strong {
  color: var(--text-main);
}

/* Clean Reflection Questions */
.questions-simple-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin: 20px 0;
}

.q-simple-item {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  font-size: var(--font-size-sm);
  line-height: 1.65;
}

.q-num {
  font-weight: 700;
  color: var(--brand-blue);
  flex-shrink: 0;
}

/* Scratchpad */
.scratchpad-simple {
  margin-top: 22px;
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  background-color: var(--bg-card-subtle);
  padding: 16px 18px;
}

.scratchpad-top {
  display: flex;
  justify-content: space-between;
  margin-bottom: 8px;
  font-size: var(--font-size-xs);
  color: var(--text-muted);
}

.scratchpad-textarea {
  width: 100%;
  min-height: 100px;
  padding: 12px 14px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: var(--font-size-sm);
  color: var(--text-main);
  resize: vertical;
  line-height: 1.6;
}

.scratchpad-textarea:focus {
  outline: none;
  border-color: var(--brand-blue);
}

/* Simple Responsive Video Frame */
.video-simple-frame {
  margin: 24px 0;
  border-radius: var(--radius-sm);
  overflow: hidden;
  border: 1px solid var(--border-card);
  background-color: #000000;
  width: 100%;
}

.video-box-ratio {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
}

.video-box-ratio iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.video-footer-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background-color: var(--bg-card-subtle);
  border-top: 1px solid var(--border-card);
  font-size: var(--font-size-xs);
  flex-wrap: wrap;
  gap: 8px;
}

.video-footer-text {
  color: var(--text-muted);
}

.video-external-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: #ff0000;
  font-weight: 600;
  font-size: var(--font-size-xs);
  text-decoration: none;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background-color: rgba(255, 0, 0, 0.08);
  border: 1px solid rgba(255, 0, 0, 0.15);
  transition: all var(--transition-fast);
}

.video-external-btn:hover {
  background-color: #ff0000;
  color: #ffffff;
  border-color: #ff0000;
}

/* Biases Simple List */
.biases-simple-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin: 20px 0;
}

.bias-simple-item {
  padding: 18px 20px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
}

.bias-simple-title {
  font-size: var(--font-size-base);
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 6px;
}

.bias-simple-desc {
  font-size: var(--font-size-sm);
  color: var(--text-main);
  line-height: 1.65;
}

.bias-simple-drive {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 6px;
  line-height: 1.6;
}

/* Clean Analysis Cards */
.analysis-simple-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin: 20px 0;
}

.analysis-simple-card {
  padding: 18px 20px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  line-height: 1.65;
}

.analysis-simple-card strong {
  color: var(--text-main);
}

/* Simple Triad */
.triad-simple-box {
  margin: 24px 0;
  padding: 20px 24px;
  border: 1px solid var(--border-card);
  background-color: var(--bg-card-subtle);
  border-radius: var(--radius-sm);
  text-align: center;
}

.triad-simple-title {
  font-size: var(--font-size-base);
  font-weight: 700;
  margin-bottom: 6px;
}

.triad-simple-pills {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 10px;
}

.triad-simple-pill {
  padding: 6px 16px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-full);
  font-size: 13px;
  font-weight: 700;
  color: var(--brand-blue);
}

/* 4 Factors Simple Grid */
.factors-simple-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin: 22px 0;
}

.factor-simple-card {
  padding: 18px 20px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
}

.factor-simple-title {
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--brand-blue);
  margin-bottom: 10px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.factor-simple-card ul {
  list-style: none;
  font-size: var(--font-size-sm);
  line-height: 1.8;
}

/* Simple Quiz */
.quiz-simple-container {
  margin: 22px 0;
  padding: 26px 28px;
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
}

.quiz-simple-q {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 20px;
  line-height: 1.45;
}

.quiz-simple-options {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 22px;
}

.quiz-simple-opt {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 18px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
  text-align: left;
  transition: all var(--transition-fast);
}

.quiz-simple-opt:hover {
  background-color: var(--nav-hover-bg);
  border-color: var(--brand-blue);
}

.quiz-simple-opt.selected {
  border-color: var(--brand-blue);
  background-color: var(--nav-active-bg);
}

.quiz-simple-opt.correct {
  border-color: #10b981 !important;
  background-color: rgba(16, 185, 129, 0.1) !important;
}

.quiz-simple-opt.incorrect {
  border-color: #ef4444 !important;
  background-color: rgba(239, 68, 68, 0.1) !important;
}

.opt-prefix {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  border: 1px solid var(--border-card);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  color: var(--text-muted);
}

.quiz-simple-opt.selected .opt-prefix {
  background-color: var(--brand-blue);
  color: #ffffff;
  border-color: var(--brand-blue);
}

.quiz-simple-actions {
  display: flex;
  gap: 12px;
}

.btn-simple-primary {
  padding: 10px 22px;
  background-color: var(--brand-navy);
  color: #ffffff;
  font-size: var(--font-size-xs);
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

[data-theme="dark"] .btn-simple-primary {
  background-color: var(--brand-blue);
}

.btn-simple-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-simple-secondary {
  padding: 10px 20px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  color: var(--text-main);
  font-size: var(--font-size-xs);
  font-weight: 600;
  border-radius: var(--radius-sm);
}

.quiz-simple-feedback {
  margin-top: 20px;
  padding: 16px 18px;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  line-height: 1.65;
}

.quiz-simple-feedback.correct {
  background-color: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.25);
  color: #065f46;
}

.quiz-simple-feedback.incorrect {
  background-color: rgba(239, 68, 68, 0.1);
  border: 1px solid rgba(239, 68, 68, 0.25);
  color: #991b1b;
}

[data-theme="dark"] .quiz-simple-feedback.correct { color: #6ee7b7; }
[data-theme="dark"] .quiz-simple-feedback.incorrect { color: #fca5a5; }

/* Course Completion Simple Box */
.completion-simple-box {
  margin-top: 28px;
  padding: 28px;
  border: 1px solid var(--border-card);
  background-color: var(--bg-card-subtle);
  border-radius: var(--radius-sm);
  text-align: center;
}

.completion-simple-title {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 8px;
}

.completion-simple-desc {
  font-size: var(--font-size-sm);
  color: var(--text-muted);
  margin-bottom: 20px;
}

.completion-simple-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
}

/* --- Sticky Bottom Bar --- */
.player-bottom-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 64px;
  background-color: var(--bg-header);
  border-top: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  z-index: 90;
  padding: 0 24px;
}

.player-nav-container {
  max-width: 1140px;
  width: 92%;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.btn-nav-simple {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 18px;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 600;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.btn-nav-prev {
  background-color: var(--bg-card-subtle);
  border: 1px solid var(--border-card);
  color: var(--text-main);
}

.btn-nav-prev:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn-nav-prev:not(:disabled):hover {
  background-color: var(--nav-hover-bg);
  border-color: var(--brand-blue);
}

.btn-nav-next {
  background-color: var(--brand-navy);
  color: #ffffff;
  border: 1px solid transparent;
}

[data-theme="dark"] .btn-nav-next {
  background-color: var(--brand-blue);
}

.btn-nav-next:hover {
  opacity: 0.9;
}

.player-center-meta {
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--text-muted);
}

/* --- Mobile Responsiveness (Fully Optimized) --- */
@media (max-width: 992px) {
  .player-sidebar {
    position: fixed;
    top: 64px;
    bottom: 64px;
    left: 0;
    transform: translateX(-100%);
    box-shadow: var(--shadow-card-hover);
    width: 290px;
  }

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

  .player-sidebar-backdrop {
    display: none;
    position: fixed;
    top: 64px;
    bottom: 64px;
    left: 0;
    right: 0;
    background-color: rgba(15, 23, 42, 0.45);
    z-index: 75;
  }

  .player-sidebar-backdrop.active {
    display: block;
  }

  .viewport-inner {
    max-width: 100%;
    width: 100%;
    padding: 24px 20px 90px;
  }

  .dim-simple-list {
    grid-template-columns: 1fr;
  }

  .opinions-simple-list {
    grid-template-columns: 1fr;
  }

  .analysis-simple-grid, .factors-simple-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .player-header {
    padding: 0 14px;
  }

  .player-brand-logo .brand-logo-img {
    width: 110px;
  }

  .player-course-meta-header {
    display: none;
  }

  .player-progress-widget {
    display: none;
  }

  .viewport-inner {
    padding: 16px 12px 80px;
  }

  .lesson-content-card {
    padding: 20px 16px;
  }

  .lesson-main-title {
    font-size: 1.45rem;
  }

  .case-study-simple-box {
    padding: 18px 14px;
  }

  .btn-nav-simple {
    padding: 8px 14px;
  }
}