/* ============================================================
   VERTEX CBT — studyroom.css
   Study Room component — uses tokens from main.css
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Lora:ital,wght@0,400;0,500;0,600;0,700;1,400;1,500&family=Source+Serif+4:ital,opsz,wght@0,8..60,300;0,8..60,400;0,8..60,500;0,8..60,600;1,8..60,400&family=Inconsolata:wght@400;500&display=swap');

.sr-shell {
  height: 100dvh;
  display: flex;
  flex-direction: column;
  background: var(--bg-page);
  overflow: hidden;
}

.sr-topbar {
  position: sticky;
  top: 0;
  flex-shrink: 0;
  z-index: 50;
  background: var(--bg-base);
  border-bottom: 1px solid var(--border);
  padding: 0 1rem;
  padding-left:  max(1rem, env(safe-area-inset-left));
  padding-right: max(1rem, env(safe-area-inset-right));
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: nowrap;
  min-height: 3rem;
  overflow: hidden;
  min-width: 0;
}

.sr-topbar__back {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--text-2);
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  padding: 0.3rem 0.625rem;
  cursor: pointer;
  transition: background var(--t-fast), color var(--t-fast), border-color var(--t-fast);
  white-space: nowrap;
  font-family: var(--font);
  flex-shrink: 0;
  max-width: 180px;
  overflow: hidden;
  text-overflow: ellipsis;
}
.sr-topbar__back:hover {
  background: var(--bg-muted);
  color: var(--text-1);
  border-color: var(--border-strong);
}

.sr-topbar__title {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--text-1);
  flex: 1 1 0;
  min-width: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.sr-topbar__actions {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  flex-shrink: 0;
  flex-wrap: nowrap;
}

.sr-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  flex: 1 1 0;
  min-height: 0;
  overflow: hidden;
  min-width: 0;
}

.sr-layout--no-sidebar { grid-template-columns: 1fr; }

.sr-sidebar {
  background: var(--bg-subtle);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--sp-4) var(--sp-3);
  min-width: 0;
}

.sr-sidebar__heading {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-4);
  margin-bottom: var(--sp-3);
  padding-bottom: var(--sp-2);
  border-bottom: 1px solid var(--border);
}

.sr-sidebar__item {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-2);
  padding: 0.5rem 0.625rem;
  border-radius: var(--r-md);
  cursor: pointer;
  transition: background var(--t-fast), color var(--t-fast);
  margin-bottom: 0.125rem;
  min-width: 0;
  overflow: hidden;
}
.sr-sidebar__item:hover { background: var(--bg-muted); }
.sr-sidebar__item.is-active { background: var(--accent-subtle); }

.sr-sidebar__num {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-4);
  min-width: 1.25rem;
  margin-top: 1px;
  flex-shrink: 0;
  font-family: var(--font-mono);
}
.sr-sidebar__item.is-active .sr-sidebar__num { color: var(--accent); }

.sr-sidebar__name {
  font-size: var(--text-sm);
  font-weight: 400;
  line-height: 1.4;
  color: var(--text-2);
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  white-space: normal;
}
.sr-sidebar__item.is-active .sr-sidebar__name {
  font-weight: 600;
  color: var(--accent-text);
}

.sr-scroll-reader {
  min-height: 0;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--sp-6) var(--sp-4);
  padding-bottom: max(var(--sp-8), calc(env(safe-area-inset-bottom) + 4rem));
  transition: background var(--t-base);
  min-width: 0;
}

.sr-scroll-content {
  margin: 0 auto;
  transition: max-width var(--t-base);
  width: 100%;
  min-width: 0;
  box-sizing: border-box;
  overflow-x: hidden;
}

.sr-lesson-header {
  margin-bottom: var(--sp-6);
  padding-bottom: var(--sp-5);
  border-bottom: 1px solid var(--border);
  min-width: 0;
  overflow: hidden;
}

.sr-lesson-header__breadcrumb {
  font-size: var(--text-xs);
  color: var(--text-4);
  margin-bottom: var(--sp-2);
  display: flex;
  align-items: center;
  gap: 0.375rem;
  flex-wrap: wrap;
  min-width: 0;
  overflow: hidden;
}

.sr-lesson-header__title {
  font-family: 'Lora', 'Source Serif 4', Georgia, serif;
  font-size: 1.875rem;
  font-weight: 600;
  line-height: 1.2;
  color: var(--text-1);
  letter-spacing: -0.02em;
  margin-bottom: var(--sp-2);
  word-break: break-word;
  overflow-wrap: break-word;
  hyphens: auto;
}

.sr-lesson-header__topic {
  font-size: var(--text-base);
  color: var(--text-3);
  font-style: italic;
  word-break: break-word;
  overflow-wrap: break-word;
}

.sr-lesson-footer {
  margin-top: var(--sp-8);
  padding-top: var(--sp-5);
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--sp-3);
  min-width: 0;
  overflow: hidden;
  box-sizing: border-box;
  width: 100%;
}

.sr-lesson-nav-btn {
  max-width: 260px;
  flex-shrink: 1;
  min-width: 0;
  overflow: hidden;
}

.sr-lesson-nav-btn__label {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  min-width: 0;
}

.sr-content {
  color: var(--text-1);
  min-width: 0;
  overflow-x: hidden;
  max-width: 100%;
}

.sr-content h1, .sr-content h2, .sr-content h3,
.sr-content h4, .sr-content h5, .sr-content h6 {
  font-family: 'Lora', Georgia, serif;
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.015em;
  margin-top: 1.75em;
  margin-bottom: 0.6em;
  color: var(--text-1);
  word-break: break-word;
  overflow-wrap: break-word;
}

.sr-content h1 { font-size: 1.75em; }
.sr-content h2 { font-size: 1.45em; border-bottom: 1px solid var(--border); padding-bottom: 0.375em; }
.sr-content h3 { font-size: 1.2em; }
.sr-content h4 { font-size: 1.05em; }

.sr-content p { margin-bottom: 1.15em; orphans: 3; widows: 3; }

.sr-content ul, .sr-content ol { margin-bottom: 1.15em; padding-left: 1.75em; }
.sr-content li          { margin-bottom: 0.4em; }
.sr-content li > ul,
.sr-content li > ol     { margin-top: 0.4em; margin-bottom: 0.4em; }

.sr-content blockquote {
  border-left: 2px solid var(--accent);
  padding: 0.75em 1.25em;
  margin: 1.5em 0;
  background: var(--accent-subtle);
  border-radius: 0 var(--r-md) var(--r-md) 0;
  color: var(--text-2);
  font-style: italic;
}

.sr-content code {
  font-family: 'Inconsolata', var(--font-mono);
  font-size: 0.875em;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  padding: 0.1em 0.4em;
  color: var(--accent-text);
  word-break: break-all;
}

.sr-content pre {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 1em 1.25em;
  overflow-x: auto;
  margin-bottom: 1.15em;
  max-width: 100%;
  box-sizing: border-box;
}

.sr-content pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--text-1);
  font-size: 0.875em;
  word-break: normal;
}

.sr-content table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 1.25em;
  font-size: 0.9em;
  display: block;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  max-width: 100%;
  color: var(--text-1);
}

.sr-content thead tr {
  background: var(--accent-subtle);
}

.sr-content thead th {
  color: var(--accent-text);
  font-weight: 600;
}

.sr-content th, .sr-content td {
  border: 1px solid var(--border);
  padding: 0.5em 0.875em;
  text-align: left;
  color: var(--text-1);
}

.sr-content tbody tr:nth-child(even) {
  background: var(--bg-subtle);
}

.sr-content tbody tr:nth-child(odd) {
  background: var(--bg-base);
}

.sr-content img {
  max-width: 100%;
  height: auto;
  border-radius: var(--r-lg);
  margin: 1em 0;
  box-shadow: var(--shadow-sm);
  display: block;
}

.sr-content hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }
.sr-content strong { font-weight: 600; color: var(--text-1); }
.sr-content em     { font-style: italic; }

/* KaTeX display math overflow fix */
.sr-content .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  max-width: 100%;
  padding: 0.25em 0;
}

.sr-bg--white { background: var(--bg-page) !important; }
.sr-bg--sepia { background: #f4ead5 !important; }
.sr-bg--warm  { background: #fdf5ec !important; }

.sr-bg--sepia .sr-content,
.sr-bg--warm  .sr-content { color: #3b2f1e; }

.sr-bg--sepia .sr-content h1, .sr-bg--sepia .sr-content h2,
.sr-bg--sepia .sr-content h3, .sr-bg--sepia .sr-content h4,
.sr-bg--warm  .sr-content h1, .sr-bg--warm  .sr-content h2,
.sr-bg--warm  .sr-content h3, .sr-bg--warm  .sr-content h4 { color: #1e160a; }

.sr-bg--sepia .sr-content strong,
.sr-bg--warm  .sr-content strong { color: #1e160a; }

.sr-bg--sepia .sr-content code,
.sr-bg--warm  .sr-content code {
  background: rgba(0,0,0,.05);
  border-color: rgba(0,0,0,.1);
  color: #5a3200;
}

.sr-bg--sepia .sr-content table,
.sr-bg--warm  .sr-content table { color: #3b2f1e; }

.sr-bg--sepia .sr-content thead tr,
.sr-bg--warm  .sr-content thead tr { background: rgba(0,0,0,.08); }

.sr-bg--sepia .sr-content thead th,
.sr-bg--warm  .sr-content thead th { color: #1e160a; }

.sr-bg--sepia .sr-content th,
.sr-bg--sepia .sr-content td,
.sr-bg--warm  .sr-content th,
.sr-bg--warm  .sr-content td { border-color: rgba(0,0,0,.12); color: #3b2f1e; }

.sr-bg--sepia .sr-content tbody tr:nth-child(even),
.sr-bg--warm  .sr-content tbody tr:nth-child(even) { background: rgba(0,0,0,.04); }

.sr-bg--sepia .sr-content tbody tr:nth-child(odd),
.sr-bg--warm  .sr-content tbody tr:nth-child(odd)  { background: transparent; }

.sr-bg--sepia .sr-lesson-header__title,
.sr-bg--warm  .sr-lesson-header__title { color: #1e160a; }

.sr-bg--dark  { background: #111113 !important; color-scheme: dark; }
.sr-bg--night { background: #0d0d0f !important; color-scheme: dark; }

.sr-bg--dark,
.sr-bg--night { color: #d0d0d8; }

.sr-bg--dark  .sr-content,
.sr-bg--night .sr-content { color: #d0d0d8; }

.sr-bg--dark  .sr-content h1, .sr-bg--dark  .sr-content h2,
.sr-bg--dark  .sr-content h3, .sr-bg--dark  .sr-content h4,
.sr-bg--night .sr-content h1, .sr-bg--night .sr-content h2,
.sr-bg--night .sr-content h3, .sr-bg--night .sr-content h4 { color: #f0f0f4; }

.sr-bg--dark  .sr-content strong,
.sr-bg--night .sr-content strong { color: #f0f0f4; }

.sr-bg--dark  .sr-content a,
.sr-bg--night .sr-content a { color: #8da2fa; }

.sr-bg--dark  .sr-content code,
.sr-bg--night .sr-content code {
  background: rgba(255,255,255,.08);
  border-color: rgba(255,255,255,.12);
  color: #8da2fa;
}

.sr-bg--dark  .sr-content pre,
.sr-bg--night .sr-content pre {
  background: rgba(255,255,255,.05);
  border-color: rgba(255,255,255,.08);
}

.sr-bg--dark  .sr-content pre code,
.sr-bg--night .sr-content pre code { color: #e2e2f0; }

.sr-bg--dark  .sr-content blockquote,
.sr-bg--night .sr-content blockquote {
  background: rgba(107,135,248,.1);
  border-color: #6b87f8;
  color: #b4b4c0;
}

.sr-bg--dark  .sr-content table,
.sr-bg--night .sr-content table { color: #d0d0d8; }

.sr-bg--dark  .sr-content thead tr,
.sr-bg--night .sr-content thead tr { background: rgba(107,135,248,.15); }

.sr-bg--dark  .sr-content thead th,
.sr-bg--night .sr-content thead th { color: #c0ccff; }

.sr-bg--dark  .sr-content th,
.sr-bg--dark  .sr-content td,
.sr-bg--night .sr-content th,
.sr-bg--night .sr-content td { border-color: rgba(255,255,255,.1); color: #d0d0d8; }

.sr-bg--dark  .sr-content tbody tr:nth-child(even),
.sr-bg--night .sr-content tbody tr:nth-child(even) { background: rgba(255,255,255,.04); }

.sr-bg--dark  .sr-content tbody tr:nth-child(odd),
.sr-bg--night .sr-content tbody tr:nth-child(odd)  { background: transparent; }

.sr-bg--dark  .sr-lesson-header__title,
.sr-bg--night .sr-lesson-header__title { color: #f0f0f4; }

.sr-bg--dark  .sr-lesson-header__breadcrumb,
.sr-bg--night .sr-lesson-header__breadcrumb { color: rgba(180,180,200,.5); }

.sr-bg--dark  .sr-content hr,
.sr-bg--night .sr-content hr { border-color: rgba(255,255,255,.1); }

.sr-progress-bar {
  height: 2px;
  background: var(--border);
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  pointer-events: none;
}

.sr-progress-bar__fill {
  height: 100%;
  background: var(--accent);
  transition: width 0.2s var(--ease);
}

.sr-prefs-panel {
  position: fixed;
  top: 0; right: 0; bottom: 0;
  width: 280px;
  background: var(--bg-base);
  border-left: 1px solid var(--border);
  box-shadow: var(--shadow-lg);
  z-index: 200;
  padding: var(--sp-5);
  overflow-y: auto;
  transform: translateX(100%);
  transition: transform var(--t-slow) var(--ease);
  color: var(--text-1);
}
.sr-prefs-panel.is-open { transform: translateX(0); }

.sr-prefs-panel__title {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-1);
  margin-bottom: var(--sp-4);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.sr-prefs-section { margin-bottom: var(--sp-4); }

.sr-prefs-section__label {
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-4);
  margin-bottom: var(--sp-2);
  display: block;
}

.sr-prefs-row { display: flex; gap: var(--sp-2); flex-wrap: wrap; }

.sr-pref-btn {
  flex: 1;
  min-width: 60px;
  padding: 0.375rem 0.5rem;
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  background: var(--bg-subtle);
  color: var(--text-2);
  font-size: var(--text-xs);
  font-weight: 500;
  cursor: pointer;
  text-align: center;
  transition: all var(--t-fast);
  font-family: var(--font);
}
.sr-pref-btn:hover     { border-color: var(--accent-border); background: var(--accent-subtle); color: var(--accent-text); }
.sr-pref-btn.is-active { border-color: var(--accent); background: var(--accent); color: #fff; }

.sr-pref-slider {
  width: 100%;
  accent-color: var(--accent);
  cursor: pointer;
  margin-top: var(--sp-1);
}

.sr-bg-swatch-row { display: flex; gap: var(--sp-2); align-items: center; }

.sr-bg-btn {
  width: 2.25rem; height: 2.25rem;
  border-radius: var(--r-md);
  border: 1.5px solid var(--border);
  cursor: pointer;
  transition: border-color var(--t-fast), transform var(--t-fast);
}
.sr-bg-btn:hover     { transform: scale(1.08); }
.sr-bg-btn.is-active { border-color: var(--accent); box-shadow: 0 0 0 2px var(--accent-subtle); }
.sr-bg-btn--white    { background: #f7f7f8; }
.sr-bg-btn--sepia    { background: #f4ead5; }
.sr-bg-btn--warm     { background: #fdf5ec; }
.sr-bg-btn--dark     { background: #111113; }
.sr-bg-btn--night    { background: #0d0d0f; }

.sr-shell > .sr-browser {
  flex: 1 1 0;
  min-height: 0;
  overflow-y: auto;
  overflow-x: hidden;
}

.sr-browser {
  max-width: 860px;
  margin: 0 auto;
  padding: var(--sp-5) var(--sp-4);
  width: 100%;
  box-sizing: border-box;
  min-width: 0;
}

.sr-browser__header { margin-bottom: var(--sp-5); }

.sr-browser__filters {
  display: flex;
  gap: var(--sp-3);
  flex-wrap: wrap;
  margin-bottom: var(--sp-4);
  align-items: center;
}

.sr-browser__filters select { flex: 1; min-width: 140px; max-width: 220px; width: auto !important; }

.sr-subject-group { margin-bottom: var(--sp-5); }

.sr-subject-group__header {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  margin-bottom: var(--sp-3);
  padding-bottom: var(--sp-2);
  border-bottom: 2px solid var(--accent);
  min-width: 0;
  overflow: hidden;
}

.sr-subject-group__name {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--accent-text);
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.sr-subject-group__term {
  font-weight: 400;
  opacity: 0.6;
  font-size: .9em;
  white-space: nowrap;
  flex-shrink: 0;
}

.sr-subject-group__count {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--accent-text);
  background: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  border-radius: 3px;
  padding: 1px 7px;
  flex-shrink: 0;
  white-space: nowrap;
}

.sr-lesson-card {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-3);
  background: var(--bg-base);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: var(--sp-4);
  cursor: pointer;
  transition: border-color var(--t-base), box-shadow var(--t-base), transform var(--t-base);
  margin-bottom: var(--sp-2);
  position: relative;
  overflow: hidden;
  min-width: 0;
  box-sizing: border-box;
  width: 100%;
}

.sr-lesson-card::before {
  content: '';
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 2px;
  background: transparent;
  transition: background var(--t-fast);
}

.sr-lesson-card:hover {
  border-color: var(--accent-border);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}
.sr-lesson-card:hover::before { background: var(--accent); }

.sr-lesson-card__num {
  width: 1.875rem; height: 1.875rem; min-width: 1.875rem;
  border-radius: var(--r-sm);
  background: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-xs);
  font-weight: 700;
  color: var(--accent-text);
  flex-shrink: 0;
  font-family: var(--font-mono);
}

.sr-lesson-card__body { flex: 1; min-width: 0; overflow: hidden; }

.sr-lesson-card__title {
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--text-1);
  line-height: 1.3;
  margin-bottom: .25rem;
  word-break: break-word;
  overflow-wrap: break-word;
}

.sr-lesson-card__meta { font-size: var(--text-xs); color: var(--text-4); word-break: break-word; }

.sr-lesson-card__arrow {
  color: var(--text-4);
  font-size: 1.125rem;
  line-height: 1;
  flex-shrink: 0;
  align-self: center;
  transition: color var(--t-fast), transform var(--t-fast);
}
.sr-lesson-card:hover .sr-lesson-card__arrow { color: var(--accent); transform: translateX(2px); }

.sr-empty { text-align: center; padding: var(--sp-10) var(--sp-4); color: var(--text-4); }
.sr-empty__text { font-size: var(--text-base); font-weight: 400; }

.sr-teacher-panel {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  min-width: 0;
  overflow: hidden;
}

.sr-form-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: 1.25rem;
  min-width: 0;
  overflow: hidden;
  box-sizing: border-box;
  color: var(--text-1);
}

.sr-form-card__title {
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--text-1);
  margin-bottom: 1rem;
  padding-bottom: .75rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: .5rem;
  min-width: 0;
  overflow: hidden;
}

.sr-form-card__dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

.sr-content-editor {
  font-family: 'Inconsolata', var(--font-mono) !important;
  font-size: .875rem !important;
  line-height: 1.7 !important;
  min-height: 260px !important;
  resize: vertical;
}

.sr-markdown-hint {
  font-size: .6875rem;
  color: var(--text-4);
  margin-top: .375rem;
  line-height: 1.7;
}

.sr-markdown-hint code {
  font-family: 'Inconsolata', var(--font-mono);
  background: var(--bg-muted);
  border: 1px solid var(--border);
  border-radius: 2px;
  padding: 0 3px;
  font-size: .875em;
  color: var(--text-2);
}

.sr-teacher-lessons {
  max-height: 390px;
  overflow-y: auto;
  overflow-x: hidden;
}

.sr-teacher-lesson-row {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .5625rem .875rem;
  background: var(--bg-base);
  border: 1px solid var(--border);
  border-radius: var(--r-md);
  margin-bottom: .375rem;
  transition: border-color var(--t-fast);
  min-width: 0;
  overflow: hidden;
  box-sizing: border-box;
  width: 100%;
}
.sr-teacher-lesson-row:hover { border-color: var(--accent-border); }

.sr-teacher-lesson-row__num {
  font-size: .6875rem;
  font-weight: 600;
  color: var(--accent-text);
  background: var(--accent-subtle);
  border: 1px solid var(--accent-border);
  border-radius: 3px;
  padding: 1px 6px;
  flex-shrink: 0;
  white-space: nowrap;
  font-family: var(--font-mono);
}

.sr-teacher-lesson-row__info { flex: 1; min-width: 0; overflow: hidden; }

.sr-teacher-lesson-row__title {
  font-size: .875rem;
  font-weight: 500;
  color: var(--text-1);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  display: block;
  max-width: 100%;
}

.sr-teacher-lesson-row__meta {
  font-size: .6875rem;
  color: var(--text-4);
  margin-top: 1px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  display: block;
  max-width: 100%;
}

.sr-teacher-lesson-row__actions {
  display: flex;
  gap: .25rem;
  flex-shrink: 0;
  align-items: center;
}

@media (max-width: 900px) {
  .sr-teacher-panel { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .sr-layout { grid-template-columns: 1fr; }
  .sr-sidebar { display: none; }
  .sr-lesson-header__title { font-size: 1.5rem; }
  .sr-lesson-nav-btn { max-width: 160px; }
}

@media (max-width: 640px) {
  .sr-prefs-panel {
    width: 100%;
    border-left: none;
    border-top: 1px solid var(--border);
    top: auto; bottom: 0;
    height: 72vh;
    transform: translateY(100%);
  }
  .sr-prefs-panel.is-open { transform: translateY(0); }
  .sr-topbar  { gap: .375rem; }
  .sr-browser { padding: var(--sp-3); }
  .sr-topbar__back { max-width: 120px; }
}

@keyframes sr-page-in {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.sr-animate-in { animation: sr-page-in 0.22s var(--ease) both; }