:root {
  --bg: #f4ead4;
  --panel: #fffaf0;
  --text: #1f2a2e;
  --muted: #786c5a;
  --line: #ded0b4;
  --primary: #173f66;
  --primary-dark: #102d49;
  --accent: #b97817;
  --warn: #b45309;
  --soft: #f7eedc;
  --paper: #fbf4e4;
  --brand-font: "STKaiti", "KaiTi", "Kaiti SC", "DFKai-SB", "STSong", serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Microsoft YaHei", "PingFang SC", "Segoe UI", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
}

button,
input,
select {
  font: inherit;
}

button,
.primary-link {
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fffaf0;
  color: var(--text);
  padding: 7px 12px;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

button:hover,
.primary-link:hover {
  border-color: var(--primary);
}

.primary,
.primary-link {
  color: #fff;
  background: var(--primary);
  border-color: var(--primary);
}

.primary:hover,
.primary-link:hover {
  background: var(--primary-dark);
}

.ghost {
  background: transparent;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 250, 240, 0.95);
  border-bottom: 1px solid #eadbc0;
  box-shadow: 0 10px 30px rgba(77, 54, 20, 0.06);
  backdrop-filter: blur(10px);
}

.site-header-inner {
  min-height: 72px;
  width: 100%;
  max-width: 1380px;
  margin: 0 auto;
  padding: 0 40px;
  display: grid;
  grid-template-columns: minmax(220px, 260px) minmax(360px, 1fr) minmax(220px, 260px);
  align-items: center;
  gap: 18px;
}

.brand {
  display: flex;
  gap: 10px;
  align-items: center;
  min-width: 0;
  color: var(--primary);
  font-family: var(--brand-font);
}

.brand-button {
  min-height: auto;
  padding: 0;
  border: 0;
  border-radius: 0;
  justify-content: flex-start;
  background: transparent;
  box-shadow: none;
}

.brand-button:hover {
  border-color: transparent;
  background: transparent;
}

.brand-button:focus-visible {
  outline: 2px solid rgba(185, 120, 23, 0.45);
  outline-offset: 6px;
}

.brand-mark {
  position: relative;
  width: 42px;
  height: 42px;
  border-radius: 0;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  color: #fff;
  background: linear-gradient(145deg, #214d79 0%, #173f66 65%, #123654 100%);
  border: 2px solid var(--accent);
  box-shadow: 0 8px 18px rgba(23, 63, 102, 0.18);
  transform: rotate(45deg);
}

.brand-mark::before {
  position: absolute;
  inset: 3.5px;
  border: 1.25px solid rgba(255, 248, 232, 0.92);
  border-radius: 0;
  content: "";
}

.brand-mark > span {
  position: relative;
  z-index: 1;
  color: #fff;
  font-weight: 400;
  font-size: 21px;
  line-height: 1;
  transform: translateY(-1px) rotate(-45deg);
}

.brand-copy {
  min-width: 0;
  display: grid;
  gap: 3px;
  justify-items: start;
}

.brand-copy strong,
.brand-copy span {
  display: block;
}

.brand-copy strong {
  color: var(--primary);
  font-family: var(--brand-font);
  font-size: 24px;
  line-height: 1.1;
  letter-spacing: 0.5px;
}

.brand-copy span {
  color: #c3912b;
  font-family: var(--brand-font);
  font-size: 13px;
  line-height: 1;
  letter-spacing: 0;
  width: max-content;
  padding-left: 0;
  margin-left: 1px;
}

.main-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-width: 0;
}

.nav-button {
  position: relative;
  min-height: 52px;
  justify-content: center;
  color: #5f584b;
  border-color: transparent;
  background: transparent;
  padding: 0 11px;
  white-space: nowrap;
}

.nav-button.active,
.nav-button:hover {
  color: var(--primary);
  background: transparent;
  border-color: transparent;
}

.nav-button.active::after,
.nav-button:hover::after {
  position: absolute;
  right: 14px;
  bottom: 5px;
  left: 14px;
  height: 3px;
  border-radius: 999px;
  background: var(--accent);
  content: "";
}

.login-panel {
  position: relative;
  justify-self: end;
  padding-bottom: 10px;
  margin-bottom: -10px;
}

.login-card {
  min-height: auto;
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  color: var(--text);
  padding: 8px 10px;
  border-color: transparent;
  background: transparent;
  box-shadow: none;
}

.login-card:hover,
.login-card:focus-visible,
.login-panel.open .login-card {
  border-color: #e0c99f;
  background: rgba(255, 248, 232, 0.95);
}

.login-avatar {
  width: 38px;
  height: 38px;
  border: 2px solid var(--accent);
  border-radius: 50%;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  color: #fff8e8;
  background: var(--primary);
  font-weight: 700;
}

.login-summary {
  min-width: 0;
  text-align: left;
}

.login-card strong,
.login-card span {
  display: block;
  white-space: nowrap;
}

.login-card span {
  margin-top: 2px;
  color: var(--muted);
  font-size: 12px;
}

.teacher-popover {
  position: absolute;
  top: 100%;
  right: 0;
  width: 260px;
  padding: 16px;
  border: 1px solid #e2cfab;
  border-radius: 12px;
  background: rgba(255, 250, 240, 0.98);
  box-shadow: 0 18px 38px rgba(77, 54, 20, 0.14);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px);
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
  z-index: 30;
}

.login-panel:hover .teacher-popover,
.login-panel.open .teacher-popover {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
  pointer-events: auto;
}

.teacher-popover-head {
  display: grid;
  gap: 6px;
}

.teacher-popover-label {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
}

.teacher-profile-name {
  margin: 0;
  color: var(--primary);
  font-size: 24px;
  line-height: 1.2;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.teacher-profile-lines {
  display: grid;
  gap: 8px;
  margin-top: 14px;
}

.teacher-profile-lines span {
  color: var(--muted);
  font-size: 13px;
}

.logout-button {
  width: 100%;
  margin-top: 18px;
  color: #fff;
  background: var(--primary);
  border-color: var(--primary);
}

.logout-button:hover {
  background: var(--primary-dark);
}

.app-shell {
  min-width: 0;
  max-width: 1380px;
  margin: 0 auto;
  padding: 28px 40px 48px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 22px;
  padding: 22px 24px;
  background: linear-gradient(90deg, rgba(255, 250, 240, 0.92), rgba(247, 238, 220, 0.72));
  border: 1px solid #eadbc0;
  border-radius: 8px;
  box-shadow: 0 14px 36px rgba(77, 54, 20, 0.07);
}

.topbar h1 {
  margin: 0;
  color: var(--primary);
  font-size: 28px;
}

.topbar p {
  margin: 6px 0 0;
  color: var(--muted);
}

.top-actions,
.toolbar {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.toolbar {
  margin-bottom: 16px;
}

.toolbar input,
.toolbar select,
.form-grid input,
.form-grid select {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 7px 10px;
  background: #fffdf8;
}

.toolbar input {
  min-width: 260px;
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.metric-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(140px, 1fr));
  gap: 14px;
  margin-bottom: 16px;
}

.metric {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  box-shadow: 0 10px 24px rgba(77, 54, 20, 0.04);
}

.metric span {
  color: var(--muted);
  font-size: 13px;
}

.metric strong {
  display: block;
  margin-top: 8px;
  font-size: 28px;
}

.content-grid {
  display: grid;
  gap: 16px;
}

.content-grid.two {
  grid-template-columns: minmax(0, 1fr) minmax(360px, 0.85fr);
}

.panel {
  min-width: 0;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 18px;
  box-shadow: 0 10px 24px rgba(77, 54, 20, 0.04);
}

.panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.panel-head h2 {
  margin: 0;
  color: var(--primary);
  font-size: 18px;
}

.panel-head span,
.panel-head a {
  color: var(--muted);
  font-size: 13px;
}

.table-wrap {
  overflow: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  text-align: left;
  border-bottom: 1px solid var(--line);
  padding: 11px 8px;
  white-space: nowrap;
}

th {
  color: var(--muted);
  font-weight: 600;
}

.suggestion-list {
  margin: 0;
  padding-left: 18px;
}

.suggestion-list li {
  margin: 10px 0;
  line-height: 1.55;
}

.problem-list,
.task-list,
.class-list,
.resource-list {
  display: grid;
  gap: 10px;
}

.list-card {
  width: 100%;
  text-align: left;
  display: block;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdf8;
  padding: 12px;
}

.list-card.active {
  border-color: var(--primary);
  background: var(--soft);
}

.list-card h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.list-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.5;
}

.chip-row,
.tag-cloud {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.chip,
.tag-cloud span {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  border: 1px solid #d8c8aa;
  border-radius: 999px;
  padding: 4px 9px;
  color: #42545e;
  background: #fff8e8;
  font-size: 13px;
}

.problem-detail {
  line-height: 1.65;
}

.problem-detail h3 {
  margin: 0 0 10px;
  font-size: 20px;
}

.detail-block {
  border-top: 1px solid var(--line);
  padding-top: 12px;
  margin-top: 12px;
}

.detail-block h4 {
  margin: 0 0 8px;
}

.switch,
.checkbox-row {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.form-grid {
  display: grid;
  gap: 12px;
}

.form-grid label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 13px;
}

.form-grid label input,
.form-grid label select {
  color: var(--text);
  font-size: 14px;
}

.form-actions,
.row-actions,
.import-row,
.class-summary {
  display: flex;
  align-items: center;
  gap: 8px;
}

.form-actions > * {
  flex: 1;
}

.class-picker {
  display: grid;
  gap: 6px;
  margin-bottom: 12px;
  color: var(--muted);
  font-size: 13px;
}

.class-picker select,
.import-row input {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 7px 10px;
  background: #fffdf8;
}

.compact-form {
  grid-template-columns: minmax(100px, 0.7fr) minmax(140px, 1fr) auto;
  align-items: end;
  padding: 12px 0;
  border-top: 1px solid var(--line);
}

.compact-form .form-actions {
  min-width: 170px;
}

.import-row {
  flex-wrap: wrap;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line);
}

.import-row input {
  min-width: 220px;
  flex: 1;
}

.class-summary {
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
}

.class-summary h3 {
  margin: 0 0 6px;
}

.class-summary p {
  margin: 0;
  color: var(--muted);
  line-height: 1.55;
}

.row-actions {
  flex: 0 0 auto;
  flex-wrap: wrap;
}

.row-actions button,
.button-link {
  min-height: 32px;
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fffaf0;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
}

.danger-text {
  color: #9b2626 !important;
  border-color: #dfbcbc !important;
}

.resource-missing {
  min-height: 32px;
  display: inline-flex;
  align-items: center;
  padding: 5px 9px;
  border: 1px solid #dec998;
  border-radius: 6px;
  color: #7c5a12;
  background: #fff4d5;
  white-space: nowrap;
}

.table-scroll {
  overflow-x: auto;
  margin-top: 12px;
}

.student-table th:last-child,
.student-table td:last-child {
  width: 1%;
}

.empty-state {
  padding: 18px 8px;
  color: var(--muted);
  text-align: center;
}

.checkbox-row {
  grid-template-columns: auto 1fr;
  color: var(--text);
}

.chart-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.chart-row span {
  color: var(--muted);
}

.chart-row strong {
  display: block;
  margin: 8px 0;
  font-size: 30px;
}

.bar {
  height: 10px;
  border-radius: 999px;
  background: #e6d8bd;
  overflow: hidden;
}

.bar i {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
}

.modeling-rates {
  display: grid;
  gap: 12px;
}

.rate-line {
  display: grid;
  grid-template-columns: 92px 1fr 54px;
  gap: 10px;
  align-items: center;
}

.analytics-extra {
  margin-top: 16px;
}

.type-summary {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-bottom: 14px;
}

.type-card {
  display: grid;
  gap: 6px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdf8;
}

.type-card span {
  color: var(--muted);
  font-size: 13px;
}

.type-card strong {
  color: var(--primary);
  font-size: 24px;
}

.type-card small {
  color: var(--muted);
}

.type-detail {
  display: grid;
  gap: 10px;
}

.type-detail details {
  border-top: 1px solid var(--line);
  padding-top: 10px;
}

.type-detail summary {
  cursor: pointer;
  color: var(--primary);
  font-weight: 700;
}

.type-question-list {
  display: grid;
  gap: 10px;
  margin-top: 10px;
}

.student-diagnosis-toolbar {
  margin-bottom: 12px;
}

.student-diagnosis-toolbar select {
  width: 100%;
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 7px 10px;
  background: #fffdf8;
}

.student-chart-wrap {
  margin-bottom: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fffdf8;
  overflow: hidden;
}

#student-diagnosis-chart {
  display: block;
  width: 100%;
  height: auto;
  min-height: 220px;
}

#student-diagnosis-chart .axis {
  stroke: #d8c8aa;
  stroke-width: 1;
}

#student-diagnosis-chart .chart-bars rect {
  fill: rgba(185, 120, 23, 0.28);
}

#student-diagnosis-chart .chart-line {
  fill: none;
  stroke: var(--primary);
  stroke-width: 3;
}

#student-diagnosis-chart .chart-dots circle {
  fill: var(--primary);
  stroke: #fffaf0;
  stroke-width: 2;
}

#student-diagnosis-chart .chart-labels text,
#student-diagnosis-chart text {
  fill: var(--muted);
  font-size: 12px;
}

#toast {
  position: fixed;
  right: 22px;
  bottom: 22px;
  min-width: 180px;
  max-width: 360px;
  padding: 12px 14px;
  border-radius: 8px;
  color: #fff;
  background: var(--primary-dark);
  opacity: 0;
  pointer-events: none;
  transform: translateY(12px);
  transition: 0.2s ease;
}

#toast.show {
  opacity: 1;
  transform: translateY(0);
}

@media (max-width: 980px) {
  .site-header {
    position: static;
  }

  .site-header-inner {
    grid-template-columns: 1fr;
    gap: 12px;
    padding: 16px 20px;
  }

  .main-nav {
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 4px;
  }

  .login-panel {
    justify-self: start;
  }

  .teacher-popover {
    left: 0;
    right: auto;
  }

  .content-grid.two,
  .metric-grid,
  .type-summary {
    grid-template-columns: 1fr;
  }

  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .app-shell {
    padding: 20px;
  }

  .brand-copy strong {
    font-size: 22px;
  }
}

.video-layout {
  grid-template-columns: minmax(300px, 0.78fr) minmax(0, 1.22fr);
  align-items: stretch;
}

.video-link-layout {
  margin-top: 24px;
}

.video-upload-panel,
.video-library-panel {
  height: 100%;
}

.video-form {
  gap: 18px;
}

.video-file-field {
  gap: 8px;
}

.video-file-picker {
  min-height: 54px;
  display: flex;
  align-items: center;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  background: #fffdf8;
}

.video-file-picker button {
  flex: 0 0 auto;
}

#video-file-name {
  color: var(--muted);
  font-size: 14px;
  word-break: break-all;
}

#video-file-name.is-error {
  color: #d14343;
}

.video-field-hint {
  margin: -8px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.video-library-panel {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.video-search-wrap {
  display: grid;
  gap: 8px;
}

.video-search-box {
  display: flex;
  align-items: center;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #fffdf8;
  overflow: hidden;
}

.video-search-box input {
  width: 100%;
  min-height: 48px;
  border: 0;
  padding: 0 18px;
  background: transparent;
  outline: none;
}

.video-search-button {
  min-width: 52px;
  border: 0;
  border-left: 1px solid #eadbc0;
  border-radius: 0;
  background: transparent;
}

.video-search-button img {
  width: 20px;
  height: 20px;
}

.video-keyword-list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-bottom: 2px;
}

.video-keyword {
  min-height: 34px;
  padding: 6px 14px;
  border-radius: 8px;
  background: #f7eedc;
  color: var(--text);
}

.video-keyword:hover {
  background: #efe2c5;
}

.video-empty {
  display: none;
  place-items: center;
  min-height: 120px;
  color: var(--muted);
  font-size: 18px;
}

.video-empty.is-visible {
  display: grid;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(var(--video-grid-columns, 3), minmax(0, 1fr));
  gap: 18px;
  align-items: start;
  margin-top: 0;
}

.video-card {
  position: relative;
  min-height: 0;
  width: 100%;
  display: grid;
  gap: 10px;
  padding: 0;
  border: 1px solid #e0d1b5;
  border-radius: 14px;
  background: transparent;
  box-shadow: none;
  overflow: hidden;
}

.video-card-main {
  display: grid;
  gap: 10px;
  width: 100%;
  padding: 0;
  border: 0;
  border-radius: inherit;
  background: transparent;
  overflow: hidden;
}

.video-delete-button {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 4;
  min-height: 32px;
  padding: 6px 10px;
  border: 1px solid rgba(255, 255, 255, 0.72);
  border-radius: 6px;
  background: rgba(139, 38, 38, 0.92);
  color: #fff;
  font-size: 12px;
  font-weight: 700;
  box-shadow: 0 4px 12px rgba(55, 20, 20, 0.2);
}

.video-delete-button:hover,
.video-delete-button:focus-visible {
  background: #a32626;
}

.video-card:hover {
  border-color: #c7ad79;
}

.video-card-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: #193654;
}

.video-card-media {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transform-origin: center center;
  transition: transform 0.24s ease;
  pointer-events: none;
}

.video-card:hover .video-card-media {
  transform: scale(var(--video-preview-hover-scale, 1.2));
}

.video-link-card-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  transform-origin: center center;
  transition: transform 0.24s ease;
  pointer-events: none;
}

.video-link-card:hover .video-link-card-image {
  transform: scale(var(--video-link-preview-hover-scale, 1.5));
}

.video-card-overlay {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 12px;
  color: #fff;
  font-size: 12px;
  background: linear-gradient(180deg, transparent, rgba(0, 0, 0, 0.68));
}

.video-link-card-overlay {
  justify-content: flex-start;
  transition: opacity 0.18s ease;
}

.video-link-card:hover .video-link-card-overlay {
  opacity: 0;
}

.video-card-title-wrap {
  position: relative;
  padding: 0 12px 14px;
}

.video-card-title {
  margin: 0;
  color: #151515;
  font-size: 15px;
  line-height: 1.5;
  text-align: left;
  display: -webkit-box;
  overflow: hidden;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
}

.video-card-title-popup {
  position: absolute;
  right: 12px;
  left: 12px;
  bottom: calc(100% - 6px);
  padding: 10px 12px;
  border: 1px solid #dfcfb2;
  border-radius: 10px;
  background: rgba(255, 250, 240, 0.98);
  color: var(--text);
  text-align: left;
  line-height: 1.5;
  opacity: 0;
  pointer-events: none;
  transform: translateY(6px);
  transition: opacity 0.18s ease, transform 0.18s ease;
  box-shadow: 0 12px 24px rgba(77, 54, 20, 0.12);
  z-index: 3;
}

.video-card-title-wrap:hover .video-card-title-popup {
  opacity: 1;
  transform: translateY(0);
}

.video-card-placeholder {
  min-height: 236px;
  border-color: transparent;
  background: transparent;
  pointer-events: none;
}

.video-pagination {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 16px;
  margin-top: 4px;
}

.video-pagination.is-empty {
  grid-template-columns: 1fr;
}

.video-page-center {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  color: var(--text);
}

.video-page-center input {
  width: 72px;
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 10px;
  background: #fffdf8;
  text-align: center;
}

.video-page-button {
  min-width: 84px;
  min-height: 42px;
  border-radius: 12px;
  border-color: #d7c8ad;
  background: #ece5d8;
  color: var(--text);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 1px;
}

.video-page-button[hidden] {
  display: none;
}

.video-player-panel {
  display: grid;
  gap: 18px;
}

.video-player-back {
  justify-self: start;
}

.video-player-box {
  max-width: 1080px;
  margin: 0 auto;
  padding: 6px 0 0;
}

.video-player-header {
  display: grid;
  gap: 10px;
  margin-bottom: 16px;
}

#video-player-title {
  margin: 0;
  color: #1b1b1b;
  font-size: 28px;
  line-height: 1.25;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.video-player-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  color: #9d978d;
  font-size: 14px;
}

.video-player-divider {
  color: #b6afa4;
}

.video-player-shell {
  border-radius: 18px;
  overflow: hidden;
  box-shadow: 0 16px 34px rgba(23, 63, 102, 0.12);
  background: #000;
}

.video-player-shell video {
  width: 100%;
  max-height: 70vh;
  display: block;
  background: #000;
}

@media (max-width: 1100px) {
  .video-layout {
    grid-template-columns: 1fr;
  }

  .video-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.selection-grid { display:grid; grid-template-columns:repeat(2,minmax(0,1fr)); gap:8px; max-height:220px; overflow:auto; }
.artifact-preview { white-space:pre-wrap; overflow:auto; max-height:320px; padding:12px; background:#f5f7f8; border-radius:6px; }
.full-row { grid-column:1 / -1; }

@media (max-width: 640px) {
  .selection-grid { grid-template-columns:1fr; }
  .compact-form {
    grid-template-columns: 1fr;
  }

  .class-summary {
    align-items: stretch;
    flex-direction: column;
  }

  .class-summary .row-actions {
    width: 100%;
  }

  .class-summary .row-actions > * {
    flex: 1;
  }

  .video-grid {
    grid-template-columns: 1fr;
  }

  .video-pagination {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .video-page-center {
    flex-wrap: wrap;
  }

  .video-page-button {
    width: 100%;
  }

  #video-player-title {
    font-size: 22px;
  }
}