:root {
  --bg: #f7f8f3;
  --ink: #17212b;
  --muted: #5f6b78;
  --surface: #ffffff;
  --surface-strong: #f0f4f5;
  --line: #d7dee3;
  --line-strong: #a7b3bd;
  --teal: #0f766e;
  --teal-dark: #115e59;
  --blue: #315f82;
  --gold: #a16207;
  --green: #16733a;
  --red: #b42318;
  --focus: #ffbf47;
  --shadow: 0 18px 45px rgba(23, 33, 43, 0.12);
}

* {
  box-sizing: border-box;
}

html {
  min-width: 320px;
  background: var(--bg);
  color: var(--ink);
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.5;
}

body {
  margin: 0;
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

a {
  color: var(--blue);
}

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: 1rem;
  z-index: 20;
  transform: translateY(-150%);
  border-radius: 6px;
  background: var(--ink);
  color: #ffffff;
  padding: 0.7rem 1rem;
  text-decoration: none;
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border-bottom: 1px solid var(--line);
  background: var(--surface);
  padding: 1rem clamp(1rem, 3vw, 2rem);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand-block {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  min-width: 0;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  flex: 0 0 auto;
  width: 3rem;
  height: 3rem;
  border-radius: 8px;
  background: var(--teal);
  color: #ffffff;
  font-weight: 800;
}

.eyebrow {
  margin: 0 0 0.2rem;
  color: var(--gold);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
h4,
p {
  overflow-wrap: anywhere;
}

h1 {
  margin: 0;
  font-size: clamp(1.25rem, 3vw, 1.75rem);
}

.header-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 1rem;
  min-width: min(34rem, 50vw);
}

.progress-summary {
  display: grid;
  gap: 0.35rem;
  min-width: min(20rem, 36vw);
}

.meter-label {
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 700;
}

.meter {
  display: block;
  height: 0.65rem;
  overflow: hidden;
  border-radius: 999px;
  background: #e5e7eb;
}

.meter span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--teal), var(--blue));
  transition: width 180ms ease;
}

.layout-shell {
  display: grid;
  grid-template-columns: 17rem minmax(0, 1fr);
  min-height: calc(100vh - 5rem);
}

.tab-sidebar {
  border-right: 1px solid var(--line);
  background: #eef3f1;
  padding: 1rem;
}

.tab-list {
  display: grid;
  gap: 0.55rem;
  position: sticky;
  top: 6rem;
}

.tab-button {
  display: grid;
  grid-template-columns: 4.25rem 1fr;
  align-items: center;
  gap: 0.75rem;
  width: 100%;
  min-height: 3.3rem;
  border: 1px solid transparent;
  border-radius: 8px;
  background: transparent;
  color: var(--ink);
  padding: 0.55rem 0.65rem;
  text-align: left;
}

.tab-button span {
  border-radius: 999px;
  background: var(--surface);
  color: var(--blue);
  font-size: 0.8rem;
  font-weight: 800;
  padding: 0.25rem 0.55rem;
  text-align: center;
}

.tab-button strong {
  font-size: 0.95rem;
}

.tab-button.active {
  border-color: var(--teal);
  background: var(--surface);
  box-shadow: 0 8px 18px rgba(23, 33, 43, 0.08);
}

.tab-button.done span {
  background: #dff3e6;
  color: var(--green);
}

.content-shell {
  min-width: 0;
  padding: clamp(1rem, 3vw, 2.25rem);
}

.tab-panel {
  display: grid;
  gap: 1.25rem;
}

.page-heading {
  max-width: 62rem;
}

.page-heading h2 {
  margin: 0;
  font-size: clamp(1.75rem, 4vw, 3.2rem);
  line-height: 1.1;
}

.page-heading p:not(.eyebrow) {
  max-width: 55rem;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.15rem);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.6rem;
  border: 1px solid var(--teal);
  border-radius: 8px;
  background: var(--teal);
  color: #ffffff;
  font-weight: 800;
  padding: 0.65rem 0.95rem;
}

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

.button-secondary {
  border-color: var(--line-strong);
  background: var(--surface);
  color: var(--ink);
}

.button-secondary:hover {
  border-color: var(--blue);
  background: #f1f6f8;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.visual-band {
  display: grid;
  grid-template-columns: minmax(14rem, 1.1fr) auto minmax(14rem, 1fr);
  gap: 1rem;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: linear-gradient(135deg, #ffffff, #edf6f2 55%, #f8f2df);
  padding: clamp(1rem, 3vw, 1.5rem);
}

.wide-table-visual,
.related-tables-visual {
  min-height: 10rem;
  border: 2px solid rgba(23, 33, 43, 0.16);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.86);
  padding: 1rem;
}

.wide-table-visual > span,
.related-tables-visual span {
  font-weight: 800;
}

.mini-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.35rem;
  margin-top: 1rem;
}

.mini-grid span {
  min-height: 1.45rem;
  border-radius: 4px;
  background: #d9e3e8;
}

.mini-grid span:nth-child(4n),
.mini-grid span:nth-child(7) {
  background: #f3d49b;
}

.flow-arrow {
  color: var(--blue);
  font-weight: 900;
  text-align: center;
  text-transform: uppercase;
}

.related-tables-visual {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.65rem;
}

.related-tables-visual span {
  display: grid;
  place-items: center;
  min-height: 3rem;
  border-radius: 6px;
  border: 1px solid #cad6dc;
  background: #ffffff;
  color: var(--blue);
}

.concept-grid,
.quiz-grid,
.glossary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1rem;
}

.concept-card,
.term-card,
.review-step {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  padding: 1rem;
}

.concept-card h3,
.term-card h3,
.review-step strong {
  margin: 0 0 0.35rem;
}

.concept-card p,
.term-card p,
.review-step p {
  margin: 0;
  color: var(--muted);
}

.lesson-panel,
.activity-panel,
.solution-block {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  padding: clamp(1rem, 2.5vw, 1.35rem);
}

.lesson-panel h3,
.activity-panel h3,
.solution-block h3 {
  margin-top: 0;
}

.lesson-panel h4 {
  margin: 0 0 0.35rem;
  font-size: 1rem;
}

.lesson-panel p {
  color: var(--muted);
}

.lesson-columns {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1rem;
  margin: 1rem 0;
}

.lesson-columns > div {
  border-left: 4px solid #bfd2da;
  padding-left: 0.9rem;
}

.lesson-columns p {
  margin: 0;
}

.lesson-callout {
  border-left: 4px solid var(--teal);
  background: #edf8f4;
  color: var(--ink);
  margin-top: 1rem;
  padding: 0.9rem 1rem;
}

.lesson-callout strong {
  color: var(--teal-dark);
}

.dependency-list {
  display: grid;
  gap: 0.85rem;
  margin: 1rem 0;
}

.dependency-list > div {
  border-left: 4px solid #d8b867;
  padding-left: 0.9rem;
}

.dependency-list strong {
  color: var(--ink);
}

.dependency-list p {
  margin: 0.2rem 0 0;
}

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

.number-list,
.check-list,
.schema-list {
  padding-left: 1.35rem;
}

.number-list li,
.check-list li,
.schema-list li {
  margin: 0.35rem 0;
}

.workspace-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.45fr) minmax(19rem, 0.8fr);
  gap: 1rem;
  align-items: start;
}

.three-column-activity {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  align-items: start;
}

.table-wrap {
  max-width: 100%;
  overflow-x: auto;
}

table {
  width: 100%;
  min-width: 38rem;
  border-collapse: collapse;
  font-size: 0.95rem;
}

caption {
  margin-bottom: 0.65rem;
  color: var(--ink);
  font-weight: 900;
  text-align: left;
}

th,
td {
  border: 1px solid var(--line);
  padding: 0.65rem 0.75rem;
  text-align: left;
  vertical-align: top;
}

th {
  background: #e9eef1;
  color: var(--ink);
}

tbody tr:nth-child(even) {
  background: #fafafa;
}

.key-field,
.key-cell {
  background: #e6f4ef;
}

.key-tag {
  display: inline-block;
  margin-left: 0.45rem;
  border-radius: 999px;
  background: var(--teal);
  color: #ffffff;
  font-size: 0.72rem;
  font-weight: 900;
  padding: 0.1rem 0.45rem;
}

.key-swatch {
  display: inline-block;
  width: 0.85rem;
  height: 0.85rem;
  border-radius: 3px;
  background: #e6f4ef;
  border: 1px solid var(--teal);
  vertical-align: -0.1rem;
}

.table-note {
  margin: 0.65rem 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.cell-button {
  width: 100%;
  min-height: 3rem;
  border: 2px solid transparent;
  border-radius: 6px;
  background: transparent;
  color: inherit;
  padding: 0.2rem;
  text-align: left;
}

.selectable-cell {
  padding: 0.25rem;
}

.selected-cell .cell-button {
  border-color: var(--blue);
  background: #e6f0f7;
}

.problem-cell.selected-cell .cell-button {
  border-color: var(--green);
  background: #e6f5ec;
}

.choice-group {
  display: grid;
  gap: 0.6rem;
  margin: 0 0 1rem;
  border: 0;
  padding: 0;
}

.choice-group legend {
  margin-bottom: 0.55rem;
  color: var(--ink);
  font-weight: 800;
}

.choice-group.compact {
  gap: 0.45rem;
}

.choice-option {
  display: grid;
  grid-template-columns: 1.25rem 1fr;
  align-items: start;
  gap: 0.55rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfcfc;
  padding: 0.65rem;
}

.choice-option input {
  margin-top: 0.18rem;
}

.choice-option:has(input:checked) {
  border-color: var(--teal);
  background: #edf8f4;
}

.hint-box,
.feedback,
.inline-feedback,
.quiz-score {
  border-radius: 8px;
  padding: 0.85rem 1rem;
}

.hint-box {
  border: 1px solid #e6c56f;
  background: #fff7df;
  color: #553f03;
  margin-bottom: 1rem;
}

.feedback {
  display: grid;
  gap: 0.25rem;
  margin-top: 1rem;
  border: 1px solid var(--line);
}

.feedback.success {
  border-color: #8cc7a4;
  background: #ecf8ef;
}

.feedback.warning {
  border-color: #e2bd72;
  background: #fff8e8;
}

.inline-feedback {
  margin: 0.3rem 0 0;
  font-size: 0.92rem;
}

.inline-feedback.good {
  background: #ecf8ef;
  color: #0f5132;
}

.inline-feedback.needs-work {
  background: #fff8e8;
  color: #6b4a05;
}

.solution-block {
  display: grid;
  gap: 1rem;
  border-color: #b9cbd5;
  background: #fbfcfd;
}

.table-set {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(18rem, 1fr));
  gap: 1rem;
}

.schema-table {
  min-width: 0;
}

.schema-table h4 {
  margin: 0 0 0.35rem;
}

.schema-table p {
  margin: 0 0 0.8rem;
  color: var(--muted);
}

.schema-table table {
  min-width: 24rem;
  font-size: 0.88rem;
}

.dependency-map {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1rem;
}

.node {
  border: 2px solid var(--blue);
  border-radius: 8px;
  background: #eef6fb;
  color: var(--ink);
  font-weight: 900;
  padding: 0.7rem 0.85rem;
}

.key-node {
  border-color: var(--teal);
  background: #e8f6f2;
}

.warning-node {
  border-color: var(--gold);
  background: #fff4d6;
}

.connector {
  color: var(--muted);
  font-weight: 800;
}

.practice-switcher {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.pill-button {
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: var(--surface);
  color: var(--ink);
  font-weight: 800;
  padding: 0.55rem 0.85rem;
}

.pill-button.active {
  border-color: var(--teal);
  background: #e8f6f2;
  color: var(--teal-dark);
}

.match-list {
  display: grid;
  gap: 0.65rem;
}

.match-row {
  display: grid;
  grid-template-columns: minmax(7rem, 1fr) minmax(10rem, 1fr);
  gap: 0.75rem;
  align-items: center;
}

.match-row select {
  min-height: 2.5rem;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: var(--surface);
  color: var(--ink);
  padding: 0.45rem 0.55rem;
}

.quiz-score {
  width: fit-content;
  border: 1px solid #b6c9d6;
  background: #eef6fb;
}

.review-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
}

.review-step span {
  display: inline-block;
  margin-bottom: 0.5rem;
  border-radius: 999px;
  background: #edf1f3;
  color: var(--blue);
  font-weight: 900;
  padding: 0.2rem 0.55rem;
}

.review-step.complete {
  border-color: #9bd4b0;
  background: #f2fbf5;
}

.review-step.complete span {
  background: #dff3e6;
  color: var(--green);
}

.glossary-grid {
  align-items: start;
}

.term-card {
  min-height: 9rem;
}

.toast {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  z-index: 30;
  max-width: min(24rem, calc(100vw - 2rem));
  transform: translateY(150%);
  border-radius: 8px;
  background: var(--ink);
  color: #ffffff;
  font-weight: 800;
  padding: 0.85rem 1rem;
  box-shadow: var(--shadow);
  transition: transform 180ms ease;
}

.toast-visible {
  transform: translateY(0);
}

@media (max-width: 1050px) {
  .layout-shell {
    grid-template-columns: 1fr;
  }

  .tab-sidebar {
    position: sticky;
    top: 5.1rem;
    z-index: 9;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    padding: 0.75rem;
  }

  .tab-list {
    grid-auto-flow: column;
    grid-auto-columns: minmax(8.25rem, 1fr);
    gap: 0.5rem;
    overflow-x: auto;
    position: static;
    padding-bottom: 0.2rem;
  }

  .tab-button {
    grid-template-columns: 1fr;
    gap: 0.3rem;
  }

  .tab-button span {
    width: fit-content;
  }

  .workspace-grid,
  .three-column-activity,
  .review-summary {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 760px) {
  .site-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .header-actions {
    align-items: stretch;
    width: 100%;
    min-width: 0;
    flex-direction: column;
  }

  .progress-summary {
    min-width: 0;
    width: 100%;
  }

  .visual-band {
    grid-template-columns: 1fr;
  }

  .flow-arrow {
    text-align: left;
  }

  .related-tables-visual {
    grid-template-columns: 1fr;
  }

  .match-row {
    grid-template-columns: 1fr;
  }

  table {
    min-width: 34rem;
  }
}