:root {
  color-scheme: light;
  --bg: #fdfaf5;
  --panel: #ffffff;
  --ink: #1e293b;
  --muted: #64748b;
  --line: #e2e8f0;
  --accent: #147d64;
  --accent-2: #7fb8d6;
  --accent-dark: #0f6350;
  --highlight: #bfe3f4;
  --good: #147d64;
  --bad: #ef4444;
  --warn: #f59e0b;
  --soft: #f1f5f9;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
  font-family: "Inter", ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.5;
}

button,
input,
select,
textarea {
  font: inherit;
}

button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 48px;
  border: 1.5px solid var(--ink);
  border-radius: 8px;
  padding: 0 24px;
  background: var(--highlight);
  color: var(--ink);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 2px 2px 0 var(--ink);
  transition: background 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease;
}

button:hover {
  background: var(--highlight);
  box-shadow: 3px 3px 0 var(--ink);
  transform: translate(-1px, -1px);
}

button:active {
  box-shadow: 0 0 0 var(--ink);
  transform: translate(1px, 1px);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

button.ghost {
  background: #fff;
  color: var(--ink);
}

button.success {
  background: var(--good);
  color: #fff;
}

button.danger {
  background: var(--bad);
  color: #fff;
}

button.danger:hover {
  background: var(--bad);
}

.topbar {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  padding: 28px clamp(16px, 4vw, 48px) 20px;
  background: var(--panel);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 6px;
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0.5rem;
  color: var(--ink);
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 700;
  line-height: 1.05;
}

h2 {
  margin-bottom: 1rem;
  color: var(--ink);
  font-size: 1.5rem;
  font-weight: 700;
}

h3 {
  margin-bottom: 16px;
  color: var(--ink);
  font-size: 1.05rem;
  font-weight: 700;
}

h4 {
  color: var(--ink);
  font-weight: 700;
}

main {
  padding: 28px clamp(16px, 4vw, 48px) 48px;
}

.tabs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.tab {
  border-radius: 999px;
  background: #fff;
  border-color: var(--line);
  color: var(--muted);
  font-weight: 600;
  box-shadow: none;
  white-space: nowrap;
}

.tab.is-active,
.tab.active {
  background: var(--highlight);
  border-color: var(--ink);
  color: var(--ink);
}

.view {
  display: none;
}

.view.is-active {
  display: block;
}

.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
}

.section-heading p,
.hint {
  color: var(--muted);
}

.section-heading.compact {
  margin-bottom: 12px;
}

.grid {
  display: grid;
  gap: 18px;
}

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

.grid.sidebar {
  grid-template-columns: minmax(260px, 340px) minmax(0, 1fr);
}

.grid.sidebar.session-fullscreen {
  display: block;
}

.grid.sidebar.session-fullscreen .setup {
  display: none;
}

.panel {
  margin-bottom: 18px;
  padding: 24px;
  background: var(--panel);
  border: 1.5px solid var(--line);
  border-radius: 12px;
  box-shadow: var(--shadow);
}

label,
fieldset {
  display: grid;
  gap: 8px;
  margin: 0 0 14px;
  color: #344054;
  font-weight: 700;
}

fieldset {
  padding: 0;
  border: 0;
}

legend {
  margin-bottom: 8px;
  font-weight: 800;
}

input,
select,
textarea {
  width: 100%;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  background: #f8fafc;
  color: var(--ink);
  font-size: 1rem;
}

input,
select {
  height: 48px;
}

input:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--accent);
  background: #fff;
}

textarea {
  min-height: 210px;
  resize: vertical;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: 0.9rem;
}

.button-row {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.add-student-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  margin: -4px 0 6px;
}

.add-student-row button {
  min-width: 72px;
}

.progress-wrap {
  display: grid;
  gap: 8px;
  margin: 14px 0;
}

.progress-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: #344054;
  font-size: 0.9rem;
  font-weight: 750;
}

.progress-track {
  position: relative;
  height: 12px;
  overflow: hidden;
  border-radius: 999px;
  background: var(--soft);
}

.progress-bar {
  width: 0%;
  height: 100%;
  border-radius: inherit;
  background: var(--accent);
  transition: width 420ms ease;
}

.upload-list {
  display: grid;
  gap: 8px;
  margin-top: 16px;
}

.upload-item,
.shared-session-item,
.validation div,
.stat,
.difficulty-stat {
  border: 1.5px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  background: #fbfcfe;
}

.upload-zone {
  border: 2px dashed var(--line);
  border-radius: 8px;
  padding: 40px 20px;
  text-align: center;
  background: #fafafa;
  margin-bottom: 16px;
}

.shared-session-list {
  display: grid;
  gap: 10px;
  margin-top: 16px;
}

.shared-session-list h4 {
  margin: 0;
}

.shared-session-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
}

.shared-session-item span,
.shared-session-item small {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

.shared-session-item button {
  width: auto;
}

.validation {
  display: grid;
  gap: 8px;
  margin-top: 14px;
}

.validation .ok {
  border-color: rgba(20, 125, 100, 0.35);
  color: var(--good);
}

.validation .error {
  border-color: rgba(188, 47, 58, 0.35);
  color: var(--bad);
}

.hint.ok {
  color: var(--good);
}

.hint.error {
  color: var(--bad);
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  min-width: 760px;
}

th,
td {
  padding: 12px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

th {
  color: #475467;
  font-size: 0.82rem;
  text-transform: uppercase;
}

.check-list {
  display: grid;
  gap: 8px;
}

.check-list.inline {
  display: flex;
  flex-wrap: wrap;
}

.check-list label {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 8px 10px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  font-weight: 650;
}

.check-list.inline label {
  min-width: 92px;
  justify-content: flex-start;
  white-space: nowrap;
}

.check-list input {
  width: auto;
}

.trainer {
  min-height: 520px;
}

.session-fullscreen .trainer {
  min-height: calc(100vh - 190px);
}

.session-start-gate {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 18px;
  padding: 18px;
  border: 1.5px solid rgba(20, 125, 100, 0.24);
  border-radius: 12px;
  background: #f8fafc;
}

.session-start-gate h3,
.session-start-gate p {
  margin: 0;
}

.session-start-gate button {
  width: auto;
  min-width: 120px;
}

#active-session.is-waiting .question-topline,
#active-session.is-waiting .question-text,
#active-session.is-waiting .question-images,
#active-session.is-waiting .answer-choices-image-wrap,
#active-session.is-waiting #answer-zone,
#active-session.is-waiting .question-actions {
  opacity: 0.42;
  pointer-events: none;
}

.empty-state {
  display: grid;
  min-height: 300px;
  place-content: center;
  text-align: center;
  color: var(--muted);
}

.question-topline {
  display: flex;
  justify-content: space-between;
  gap: 18px;
}

.timer {
  min-width: 110px;
  padding: 10px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: var(--soft);
  text-align: center;
}

.timer span {
  display: block;
  color: var(--muted);
  font-size: 0.78rem;
}

.timer strong {
  display: block;
  margin-top: 4px;
  font-size: 1.2rem;
}

.question-text {
  margin: 18px 0;
  font-size: 1.15rem;
  line-height: 1.55;
}

.question-images,
.report-images {
  display: grid;
  gap: 10px;
  margin: 12px 0 18px;
}

.question-images.is-diagram {
  justify-items: start;
  margin-bottom: 16px;
}

.question-images.is-inline-set {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  padding: 10px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
}

.question-images img,
.report-images img {
  display: block;
  max-width: 100%;
  max-height: 420px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
}

.question-images.is-diagram img {
  width: min(100%, 760px);
  max-height: 560px;
}

.question-images.is-inline-set img {
  width: auto;
  max-width: min(100%, 260px);
  max-height: 84px;
  padding: 6px;
}

.question-inline-image {
  display: inline-block;
  max-width: 170px;
  max-height: 34px;
  margin: 0 4px;
  padding: 3px 5px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: #fff;
  object-fit: contain;
  vertical-align: -0.35em;
}

.choice-inline-image {
  display: inline-block;
  max-width: 220px;
  max-height: 78px;
  margin: 0 4px;
  padding: 5px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  object-fit: contain;
  vertical-align: middle;
}

.question-region-image,
.choice-region-image {
  display: block;
  width: 100%;
  max-width: 760px;
  max-height: 520px;
  margin: 10px 0;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
}

.choice-region-image {
  max-width: 640px;
  max-height: 180px;
  margin-top: 6px;
}

.answer-choices-image-wrap {
  margin: 14px 0;
}

.answer-choices-region-image {
  display: block;
  width: 100%;
  max-width: 760px;
  max-height: 460px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
}

.report-images img {
  max-width: 220px;
  max-height: 180px;
}

.report-header {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}

.report-header > div,
.report-history-item {
  border: 1.5px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fbfcfe;
}

.report-header span,
.report-history-item span,
.report-history-item small {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

.report-header strong,
.report-history-item strong {
  display: block;
  margin-top: 4px;
  color: var(--ink);
}

.report-history {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 10px;
}

.report-history-item {
  width: 100%;
  text-align: left;
  opacity: 1;
  cursor: pointer;
}

.report-history-item.is-current {
  border-color: rgba(45, 103, 246, 0.45);
  box-shadow: 0 0 0 2px rgba(45, 103, 246, 0.12);
}

.report-question {
  display: grid;
  gap: 10px;
  min-width: 300px;
  max-width: 780px;
  line-height: 1.45;
}

.report-question p {
  margin: 0;
}

.report-question .question-region-image,
.report-question .answer-choices-region-image {
  max-width: 720px;
  max-height: 360px;
}

.report-explanation {
  min-width: 280px;
  max-width: 680px;
}

.explanation-region-image {
  display: block;
  width: 100%;
  max-width: 680px;
  max-height: 420px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
}

.report-zoomable {
  cursor: zoom-in;
}

body.is-zooming {
  overflow: hidden;
}

.image-zoom {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: grid;
  place-items: center;
  padding: 72px 24px 24px;
  background: rgba(15, 23, 42, 0.82);
}

.image-zoom.hidden {
  display: none;
}

.image-zoom img {
  display: block;
  max-width: min(96vw, 1400px);
  max-height: calc(100vh - 112px);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
  cursor: zoom-out;
}

.image-zoom-close {
  position: fixed;
  top: 20px;
  right: 24px;
  width: auto;
  border-color: rgba(255, 255, 255, 0.4);
  background: #fff;
  color: var(--ink);
}

.answer-choice {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: 10px;
  padding: 12px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
}

.answer-choice input {
  width: auto;
  margin-top: 4px;
}

.choice-images {
  display: inline-flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-left: 8px;
  vertical-align: middle;
}

.choice-images img {
  max-width: min(100%, 220px);
  max-height: 78px;
  padding: 5px;
  border: 1.5px solid var(--line);
  border-radius: 8px;
  background: #fff;
  object-fit: contain;
  vertical-align: middle;
}

.question-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin-top: 20px;
}

.jump-list {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: center;
}

.jump-list button {
  width: 38px;
  min-height: 34px;
  padding: 0;
  background: #fff;
  color: var(--ink);
  box-shadow: none;
}

.jump-list button.is-current {
  background: var(--highlight);
  color: var(--ink);
}

.jump-list button.is-answered {
  border: 2px solid var(--good);
}

.jump-list button.has-images::after {
  content: "";
  display: block;
  width: 5px;
  height: 5px;
  margin: 2px auto 0;
  border-radius: 50%;
  background: var(--accent-2);
}

.jump-list button.is-current.has-images::after {
  background: #fff;
}

.hidden {
  display: none !important;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.stat span,
.difficulty-stat span {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

.stat strong,
.difficulty-stat strong {
  display: block;
  margin-top: 4px;
  font-size: 1.35rem;
}

.result-correct {
  color: var(--good);
  font-weight: 800;
}

.result-incorrect {
  color: var(--bad);
  font-weight: 800;
}

@media (max-width: 900px) {
  .topbar,
  .section-heading,
  .question-topline,
  .question-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .grid.two,
  .grid.sidebar,
  .stats-grid {
    grid-template-columns: 1fr;
  }
}