:root {
  --ink: #17212b;
  --muted: #66717d;
  --line: #d9e0e7;
  --surface: #ffffff;
  --soft: #f5f7fa;
  --mint: #2f9f8b;
  --mint-dark: #1f7567;
  --coral: #d95d4b;
  --amber: #e8a33e;
  --blue: #3d6fb6;
  --button-hover: #eef8f5;
  --button-focus: 0 0 0 3px rgba(47, 159, 139, 0.13);
  --shadow: 0 18px 44px rgba(37, 47, 57, 0.1);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: linear-gradient(180deg, #eef4f1 0%, #f7f8f5 42%, #eef2f6 100%);
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
  transition:
    border-color 160ms ease,
    background-color 160ms ease,
    color 160ms ease,
    box-shadow 160ms ease;
}

button:disabled {
  cursor: not-allowed;
}

.auth-screen {
  display: grid;
  min-height: 100vh;
  place-items: center;
  padding: 24px;
}

.auth-screen[hidden],
.app-shell[hidden] {
  display: none;
}

.auth-card {
  display: grid;
  gap: 20px;
  width: min(100%, 420px);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 24px;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.auth-card h1 {
  margin: 4px 0 8px;
  font-size: 30px;
}

.auth-card p {
  margin: 0;
  color: var(--muted);
}

.invite-notice {
  border: 1px solid rgba(47, 159, 139, 0.3);
  border-radius: 7px;
  padding: 10px;
  background: #eef8f5;
  color: var(--mint-dark);
  font-size: 13px;
  font-weight: 800;
}

.auth-form {
  display: grid;
  gap: 14px;
}

.auth-error {
  border: 1px solid rgba(217, 93, 75, 0.45);
  border-radius: 7px;
  padding: 10px;
  background: #fff0ed;
  color: var(--coral);
  font-size: 13px;
  font-weight: 800;
}

.auth-mode-button {
  width: 100%;
}

.app-shell {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  min-height: 100vh;
}

.sidebar {
  display: flex;
  flex-direction: column;
  gap: 24px;
  padding: 24px;
  background: #16242c;
  color: #f8fbfb;
}

.brand-mark {
  display: flex;
  align-items: center;
  min-height: 64px;
  color: #ffffff;
  font-size: 22px;
  font-weight: 900;
}

.account-control,
.nav-item,
.topbar,
.panel,
.timeline-card,
.study-stage,
.student-progress {
  border-radius: 8px;
}

.topbar {
  border-radius: 0;
}

.account-control {
  display: grid;
  grid-template-columns: 42px 1fr auto;
  align-items: center;
  gap: 12px;
  margin-top: auto;
  width: 100%;
  border: 1px solid rgba(255, 255, 255, 0.14);
  padding: 10px;
  background: rgba(255, 255, 255, 0.08);
  color: #f8fbfb;
  text-align: left;
}

.account-avatar {
  display: grid;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: 8px;
  background: var(--mint);
  color: #ffffff;
  font-weight: 800;
}

.account-control strong,
.account-control span {
  display: block;
}

.account-control span {
  color: #b9c7cd;
}

.account-control i {
  color: #b9c7cd;
  font-size: 12px;
}

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

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  border: 1px solid transparent;
  padding: 12px;
  background: transparent;
  color: #dce7eb;
  text-align: left;
}

.nav-item span {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.1);
  font-size: 13px;
  font-weight: 800;
}

.nav-item.active {
  border-color: rgba(255, 255, 255, 0.16);
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
}

main {
  min-width: 0;
  padding: 0 24px 24px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 16px;
  margin: 0 -24px 24px;
  min-height: 98px;
  padding: 24px 24px 32px;
  background: #16242c;
  color: #f8fbfb;
  box-shadow: var(--shadow);
}

.eyebrow {
  display: block;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h2,
p {
  margin-top: 0;
}

.lesson-title-field,
.page-title-field {
  align-items: center;
  flex: 1;
  min-width: 220px;
  gap: 10px;
  color: inherit;
  font-size: inherit;
  font-weight: inherit;
  text-transform: none;
}

.lesson-title-field {
  display: grid;
  grid-template-columns: minmax(220px, auto) 40px 40px;
}

.page-title-field {
  display: flex;
}

.lesson-title-field[hidden],
.page-title-field[hidden],
.top-actions[hidden] {
  display: none;
}

.lesson-title-field h1,
.page-title-field h1 {
  margin: 0;
  font-size: 28px;
  line-height: 1.15;
}

.lesson-title-field h1 {
  overflow-wrap: anywhere;
}

.lesson-title-field input {
  width: 100%;
  min-height: auto;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 4px 8px;
  background: #ffffff;
  color: var(--ink);
  font-size: 28px;
  font-weight: 900;
  line-height: 1.15;
}

.lesson-title-field input:hover,
.lesson-title-field input:focus {
  border-color: var(--mint);
  box-shadow: 0 0 0 3px rgba(47, 159, 139, 0.13);
  outline: none;
}

.icon-button,
.icon-action-button {
  display: inline-grid;
  width: 40px;
  height: 40px;
  flex: 0 0 auto;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: #ffffff;
  color: var(--ink);
}

.icon-button:hover,
.icon-button:focus-visible,
.icon-action-button:hover,
.icon-action-button:focus-visible {
  border-color: var(--mint-dark);
  background: var(--button-hover);
  color: var(--mint-dark);
  outline: none;
  box-shadow: var(--button-focus);
}

.danger-button:hover,
.danger-button:focus-visible {
  border-color: var(--coral);
  background: #fff0ed;
  color: var(--coral);
  box-shadow: 0 0 0 3px rgba(217, 93, 75, 0.16);
}

h2 {
  margin-bottom: 0;
  font-size: 18px;
}

.top-actions {
  display: flex;
  gap: 10px;
}

.primary-button,
.ghost-button,
.ghost-light-button,
.danger-action-button {
  min-height: 42px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 14px;
  font-weight: 800;
}

.primary-button {
  border-color: var(--mint);
  background: var(--mint);
  color: #ffffff;
}

.primary-button:hover,
.primary-button:focus-visible {
  border-color: var(--mint-dark);
  background: var(--mint-dark);
  outline: none;
  box-shadow: var(--button-focus);
}

.ghost-button,
.ghost-light-button {
  border: 1px solid var(--line);
  background: #ffffff;
  color: var(--ink);
}

.ghost-button:hover,
.ghost-button:focus-visible,
.ghost-light-button:hover,
.ghost-light-button:focus-visible {
  border-color: var(--mint-dark);
  background: var(--button-hover);
  color: var(--mint-dark);
  outline: none;
  box-shadow: var(--button-focus);
}

.view {
  display: none;
}

.view.active {
  display: block;
}

.lessons-page {
  display: grid;
  gap: 18px;
}

.lesson-card h3,
.category-panel h3 {
  margin: 0;
}

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

.lesson-list {
  display: grid;
  gap: 12px;
  width: min(100%, 900px);
  border: 2px solid #c6d1dc;
  border-radius: 8px;
  padding: 14px;
  background: #f3f6f9;
  box-shadow: var(--shadow);
}

.lesson-filters {
  display: grid;
  grid-template-columns: minmax(260px, 1fr) minmax(160px, 220px);
  gap: 12px;
  align-items: end;
  border-bottom: 1px solid #d6dde5;
  padding-bottom: 12px;
}

.search-input {
  display: grid;
  grid-template-columns: 18px 1fr;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 10px;
  background: #ffffff;
}

.search-input i {
  color: var(--muted);
}

.search-input input {
  border: 0;
  padding: 0;
}

.search-input input:focus {
  outline: none;
}

.lessons-workspace {
  display: grid;
  grid-template-columns: minmax(220px, 280px) minmax(0, 1fr);
  gap: 18px;
  align-items: start;
}

.category-panel {
  display: grid;
  gap: 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.category-panel-header {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 10px;
  margin-bottom: 4px;
}

.category-header-actions {
  display: flex;
  gap: 4px;
}

.category-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 10px;
  background: #ffffff;
  color: var(--ink);
  text-align: left;
}

.category-item:hover,
.category-item:focus-visible {
  border-color: var(--mint-dark);
  background: var(--button-hover);
  outline: none;
  box-shadow: var(--button-focus);
}

.category-item.active {
  border-color: var(--blue);
  background: #edf4ff;
}

.category-item.drop-target {
  border-color: var(--mint-dark);
  background: #e6f4ef;
  box-shadow: 0 0 0 3px rgba(47, 159, 139, 0.16);
}

.category-new-lesson {
  margin-top: 8px;
  width: 100%;
}

.lesson-card {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: start;
  justify-content: stretch;
  gap: 16px;
  border: 2px solid #d2dbe4;
  border-radius: 8px;
  padding: 16px;
  background: #ffffff;
  box-shadow: 0 8px 18px rgba(23, 33, 43, 0.06);
}

.lesson-card[hidden] {
  display: none;
}

.lesson-card.dragging {
  opacity: 0.55;
  border-color: var(--mint);
}

.empty-state {
  border: 1px dashed #b8c4cf;
  border-radius: 8px;
  padding: 20px;
  background: #ffffff;
  color: var(--muted);
}

.empty-state h3 {
  margin: 0 0 6px;
  color: var(--ink);
}

.empty-state p {
  margin: 0;
}

.error-state {
  border-color: rgba(217, 93, 75, 0.45);
  background: #fff0ed;
}

.drag-preview {
  position: fixed;
  top: -1000px;
  left: -1000px;
  max-width: 260px;
  border: 2px solid var(--mint);
  border-radius: 8px;
  padding: 10px 12px;
  background: #ffffff;
  color: var(--ink);
  font-weight: 900;
  box-shadow: 0 14px 34px rgba(23, 33, 43, 0.18);
}

.lesson-card-main {
  display: grid;
  gap: 12px;
}

.lesson-title-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

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

.lesson-tags span {
  border-radius: 999px;
  padding: 5px 9px;
  background: #edf4ff;
  color: #284d83;
  font-size: 12px;
  font-weight: 900;
}

.assignment-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

.access-corner {
  display: flex;
  justify-content: flex-end;
  padding-top: 2px;
}

.access-count-button {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  height: auto;
  border: 0;
  padding: 0;
  background: transparent;
  color: var(--muted);
  font-weight: 900;
}

.access-count-button:hover,
.access-count-button:focus-visible {
  color: var(--ink);
  outline: none;
}

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

.modal-list span {
  border: 1px solid #d6dde5;
  border-radius: 999px;
  padding: 6px 10px;
  background: #f8fafc;
  font-size: 13px;
  font-weight: 800;
}

.modal-list p {
  margin: 0;
}

.teacher-layout {
  display: grid;
  grid-template-columns: minmax(220px, 280px) minmax(320px, 0.85fr) minmax(440px, 1.15fr);
  gap: 26px;
  align-items: start;
}

.builder-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 24px;
  border: 0;
  padding: 18px;
  box-shadow: none;
}

.builder-header .lesson-title-field {
  flex: 0 1 auto;
  max-width: min(100%, 760px);
  color: var(--ink);
}

.panel {
  border: 2px solid rgba(23, 33, 43, 0.14);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.panel-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  min-height: 62px;
  padding: 0 18px;
  border-bottom: 1px solid var(--line);
}

.block-library {
  border-color: #8fb1e4;
  border-top: 9px solid var(--blue);
  background: #edf4ff;
}

.block-library .panel-heading {
  background: var(--blue);
  color: #ffffff;
}

.lesson-canvas {
  border-color: #76cbbb;
  border-top: 9px solid var(--mint);
  background: #f7fffc;
  box-shadow: 0 24px 58px rgba(31, 117, 103, 0.18);
}

.lesson-canvas .panel-heading {
  background: var(--mint);
  color: #ffffff;
}

.inspector {
  border-color: #efc272;
  border-top: 9px solid var(--amber);
  background: #fff5e3;
}

.inspector .panel-heading {
  background: var(--amber);
  color: #ffffff;
}

.block-grid {
  display: grid;
  gap: 16px;
  padding: 14px;
}

.block-category {
  display: grid;
  gap: 8px;
}

.block-category-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  width: 100%;
  border: 0;
  padding: 0;
  background: transparent;
  color: #284d83;
  font-size: 12px;
  font-weight: 900;
  letter-spacing: 0;
  text-align: left;
  text-transform: uppercase;
}

.block-category-toggle:hover,
.block-category-toggle:focus-visible {
  color: var(--mint-dark);
  outline: none;
}

.block-category-toggle i {
  font-size: 11px;
}

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

.block-category.collapsed .block-category-list {
  display: none;
}

.block-button {
  display: grid;
  grid-template-columns: 38px 1fr;
  gap: 12px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #ffffff;
  text-align: left;
}

.block-button:hover,
.block-button:focus-visible {
  border-color: var(--mint);
  background: var(--button-hover);
  outline: none;
  box-shadow: var(--button-focus);
}

.block-icon,
.timeline-icon {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 8px;
  color: #ffffff;
  font-weight: 900;
}

.block-button strong,
.block-button span {
  display: block;
}

.block-button span:not(.block-icon) {
  margin-top: 3px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.3;
}

label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}

select,
input {
  width: 100%;
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0 10px;
  background: #ffffff;
  color: var(--ink);
}

select[multiple] {
  height: auto;
  padding: 8px;
}

select[multiple] option {
  padding: 7px;
}

.status-pill {
  border-radius: 999px;
  padding: 6px 10px;
  background: #f2efe8;
  color: #8b5a18;
  font-size: 12px;
  font-weight: 900;
}

.status-pill.open {
  background: #e6f4ef;
  color: var(--mint-dark);
}

.timeline {
  display: grid;
  gap: 12px;
  padding: 18px;
}

.timeline-card {
  display: grid;
  grid-template-columns: 28px 38px 1fr auto;
  gap: 12px;
  align-items: start;
  border: 1px solid var(--line);
  padding: 14px;
  background: #ffffff;
}

.drag-handle-button {
  display: grid;
  width: 28px;
  height: 38px;
  place-items: center;
  border: 1px solid transparent;
  border-radius: 7px;
  padding: 0;
  background: transparent;
  color: var(--muted);
  cursor: grab;
}

.drag-handle-button:hover,
.drag-handle-button:focus-visible {
  border-color: var(--line);
  background: #ffffff;
  color: var(--mint-dark);
  outline: none;
}

.timeline-card.dragging .drag-handle-button {
  cursor: grabbing;
}

.timeline-card.selected {
  border-color: var(--mint);
  box-shadow: 0 0 0 3px rgba(47, 159, 139, 0.13);
}

.timeline-card.dragging {
  opacity: 0.55;
}

.timeline-card.drop-target {
  border-color: var(--mint-dark);
  background: #eef8f5;
  box-shadow: 0 0 0 3px rgba(47, 159, 139, 0.16);
}

.timeline-card h3 {
  margin: 0 0 4px;
  font-size: 16px;
}

.timeline-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.45;
}

.mini-button {
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 7px 9px;
  background: #ffffff;
  color: var(--ink);
  font-weight: 800;
}

.mini-button:hover,
.mini-button:focus-visible {
  border-color: var(--mint-dark);
  background: var(--button-hover);
  color: var(--mint-dark);
  outline: none;
  box-shadow: var(--button-focus);
}

.inspector {
  position: sticky;
  top: 24px;
}

#inspectorContent {
  display: grid;
  gap: 14px;
  padding: 18px;
}

.field-stack {
  display: grid;
  gap: 12px;
}

.type-config {
  display: grid;
  gap: 12px;
  border: 1px solid #efc272;
  border-radius: 8px;
  padding: 12px;
  background: #fffaf0;
}

.type-config h3 {
  margin: 0;
  color: var(--ink);
  font-size: 15px;
}

.csv-importer {
  display: grid;
  gap: 12px;
  border: 1px solid #d6dde5;
  border-radius: 8px;
  padding: 12px;
  background: #ffffff;
}

.csv-importer h3 {
  margin: 0;
  color: var(--ink);
  font-size: 15px;
}

.csv-importer p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.4;
  text-transform: none;
}

.csv-help {
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 10px;
  background: #f8fafc;
}

.csv-help summary {
  cursor: pointer;
  color: var(--ink);
  font-size: 13px;
  font-weight: 900;
}

.csv-help ol {
  margin: 10px 0;
  padding-left: 18px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.csv-help span {
  display: block;
  margin-bottom: 6px;
  color: var(--ink);
  font-size: 12px;
  font-weight: 900;
  text-transform: uppercase;
}

.csv-help pre {
  overflow-x: auto;
  margin: 0;
  border-radius: 7px;
  padding: 10px;
  background: #16242c;
  color: #f8fbfb;
  font-size: 12px;
  line-height: 1.45;
}

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

.csv-actions span {
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

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

.danger-mini-button {
  color: var(--coral);
}

.danger-mini-button:hover,
.danger-mini-button:focus-visible {
  border-color: var(--coral);
  background: #fff0ed;
  color: var(--coral);
  outline: none;
  box-shadow: 0 0 0 3px rgba(217, 93, 75, 0.16);
}

.danger-action-button {
  border-color: var(--coral);
  background: var(--coral);
  color: #ffffff;
}

.danger-action-button:hover,
.danger-action-button:focus-visible {
  border-color: #b94737;
  background: #b94737;
  outline: none;
  box-shadow: 0 0 0 3px rgba(217, 93, 75, 0.16);
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  z-index: 10;
  display: grid;
  place-items: center;
  padding: 24px;
  background: rgba(16, 27, 34, 0.58);
}

.modal-backdrop[hidden] {
  display: none;
}

.modal {
  display: grid;
  gap: 16px;
  width: min(100%, 420px);
  border-radius: 8px;
  padding: 22px;
  background: #ffffff;
  box-shadow: 0 28px 70px rgba(10, 20, 28, 0.32);
}

.modal h2 {
  margin: 0;
}

.modal p {
  margin: 8px 0 0;
  color: var(--muted);
  line-height: 1.45;
}

.modal-subject {
  display: block;
  font-size: 18px;
  font-weight: 400;
}

.modal-info {
  display: flex;
  align-items: center;
  gap: 8px;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  flex-wrap: wrap;
}

.modal-field {
  text-transform: uppercase;
}

.korean-helper {
  display: grid;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: var(--soft);
}

.korean-helper[hidden] {
  display: none;
}

.korean-helper h3 {
  margin: 0;
  color: var(--ink);
  font-size: 15px;
}

.korean-helper p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
  font-weight: 500;
  line-height: 1.4;
  text-transform: none;
}

.korean-helper textarea {
  min-height: 70px;
}

.onscreen-keyboard {
  display: grid;
  gap: 8px;
  width: 100%;
  min-width: 0;
  border: 1px solid #cfd8e1;
  border-radius: 8px;
  padding: 12px;
  background: #e7edf2;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.75);
}

.keyboard-row {
  display: flex;
  gap: 6px;
  min-width: 0;
}

.keyboard-row:nth-child(2) {
  padding-left: 18px;
}

.keyboard-row:nth-child(3) {
  padding-left: 42px;
}

.keyboard-row:last-child {
  justify-content: center;
  padding-left: 0;
}

.keyboard-key {
  display: grid;
  width: 35px;
  min-width: 0;
  min-height: 42px;
  place-items: center;
  border: 1px solid #bac6d1;
  border-radius: 7px;
  padding: 5px 3px 4px;
  background: linear-gradient(180deg, #ffffff 0%, #f3f6f8 100%);
  color: var(--ink);
  box-shadow:
    0 2px 0 #b8c4cf,
    0 4px 8px rgba(23, 33, 43, 0.08);
}

.keyboard-key span {
  font-size: 15px;
  font-weight: 900;
  line-height: 1;
}

.keyboard-key small {
  color: var(--muted);
  font-size: 10px;
  font-weight: 800;
  line-height: 1;
}

.keyboard-key:hover,
.keyboard-key:focus-visible {
  border-color: var(--mint);
  color: var(--mint-dark);
  outline: none;
  transform: translateY(1px);
  box-shadow:
    0 1px 0 #b8c4cf,
    0 2px 5px rgba(23, 33, 43, 0.08);
}

.utility-key {
  width: auto;
  min-width: 96px;
}

.helper-note {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    monospace;
}

textarea {
  min-height: 94px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 10px;
  font: inherit;
}

.student-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 18px;
  align-items: stretch;
}

.invite-panel {
  margin-bottom: 18px;
}

.invite-form {
  display: grid;
  grid-template-columns: minmax(220px, 1fr) minmax(150px, 190px) auto;
  gap: 12px;
  align-items: end;
  padding: 18px;
}

.invite-link-field,
.invite-form .helper-note {
  grid-column: 1 / -1;
}

.invite-link-field input {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono",
    monospace;
}

.live-panel,
.placeholder-panel {
  max-width: 900px;
}

.live-content,
.placeholder-content {
  padding: 18px;
}

.live-content p,
.placeholder-content p {
  margin: 0;
  color: var(--muted);
}

.study-stage {
  display: grid;
  min-height: 640px;
  overflow: hidden;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.study-content {
  display: grid;
  align-content: center;
  gap: 18px;
  padding: clamp(24px, 5vw, 54px);
}

.preview-heading {
  display: grid;
  gap: 4px;
}

.preview-heading h2 {
  margin: 0;
}

.preview-block {
  display: grid;
  gap: 14px;
  border-top: 1px solid var(--line);
  padding-top: 18px;
}

.preview-block:first-of-type {
  border-top: 0;
  padding-top: 0;
}

.study-content .preview-block h2 {
  margin: 0;
  font-size: 22px;
  line-height: 1.2;
}

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

.preview-list div {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #ffffff;
}

.preview-list span {
  color: var(--muted);
}

.flashcard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 12px;
}

.flashcard-preview {
  display: grid;
  gap: 8px;
  min-height: 120px;
  align-content: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  background: #ffffff;
  color: var(--ink);
  text-align: center;
}

.flashcard-preview span {
  color: var(--muted);
}

.study-content h2 {
  font-size: clamp(28px, 4vw, 46px);
  line-height: 1.05;
}

.text-card {
  display: grid;
  gap: 10px;
  border: 1px solid var(--line);
  border-left: 5px solid var(--mint);
  border-radius: 8px;
  padding: 20px;
  background: var(--soft);
}

.text-card p {
  margin: 0;
  color: var(--muted);
}

.prompt-text {
  margin: 0;
  color: var(--ink);
  font-size: 22px;
  line-height: 1.35;
}

.answer-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.answer-grid button {
  min-height: 76px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: #ffffff;
  color: var(--ink);
  text-align: left;
  line-height: 1.35;
}

.answer-grid button:hover,
.answer-grid button:focus-visible {
  border-color: var(--mint-dark);
  background: var(--button-hover);
  outline: none;
  box-shadow: var(--button-focus);
}

.student-progress {
  padding-bottom: 18px;
}

.progress-ring {
  display: grid;
  width: 156px;
  height: 156px;
  place-items: center;
  margin: 26px auto;
  border-radius: 50%;
  background:
    radial-gradient(circle, #ffffff 0 57%, transparent 58%),
    conic-gradient(var(--mint) 0 43%, #e3e8ed 43% 100%);
}

.progress-ring span {
  font-size: 28px;
  font-weight: 900;
}

.skill-list {
  display: grid;
  gap: 10px;
  padding: 0 18px;
}

.skill-list div {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.skill-list span {
  color: var(--muted);
}

@media (max-width: 1180px) {
  .teacher-layout {
    grid-template-columns: 250px minmax(0, 1fr);
  }

  .inspector {
    position: static;
    grid-column: 1 / -1;
  }

  .keyboard-row {
    justify-content: center;
  }
}

@media (max-width: 900px) {
  .app-shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
    padding: 16px;
  }

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

  main {
    padding: 0 16px 16px;
  }

  .topbar,
  .builder-header,
  .lessons-workspace,
  .lesson-card,
  .assignment-row,
  .teacher-layout,
  .student-layout,
  .study-stage {
    grid-template-columns: 1fr;
  }

  .topbar {
    align-items: stretch;
    flex-direction: column;
    margin: 0 -16px 16px;
    min-height: auto;
    padding: 16px;
  }

  .builder-header {
    align-items: stretch;
    flex-direction: column;
  }

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

  .study-stage {
    min-height: 0;
  }

  .keyboard-row,
  .keyboard-row:nth-child(2),
  .keyboard-row:nth-child(3) {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(30px, 1fr));
    padding-left: 0;
  }

  .keyboard-key {
    width: 100%;
  }
}

@media (max-width: 560px) {
  .top-actions,
  .nav-list {
    grid-template-columns: 1fr;
  }

  .top-actions {
    display: grid;
  }

  .lesson-title-field h1,
  .lesson-title-field input {
    font-size: 24px;
  }

  .timeline-card {
    grid-template-columns: 28px 38px 1fr auto;
  }
}