:root {
  color-scheme: light;
  --bg: #f4f6f5;
  --surface: #ffffff;
  --surface-soft: #eef2f0;
  --ink: #202523;
  --muted: #68716d;
  --line: #d5ddd9;
  --accent: #176b57;
  --accent-soft: #dceee8;
  --blue: #326e94;
  --blue-soft: #e1edf4;
  --warn: #a14833;
  --warn-soft: #f7e6e1;
  --gold: #7b601c;
  --gold-soft: #f1e9ce;
  --board-light: #e7ecea;
  --board-dark: #759186;
  --board-mark: #d5c35c;
  --shadow: 0 10px 30px rgb(38 51 46 / 8%);
  --radius: 6px;
}

* {
  box-sizing: border-box;
}

html {
  min-width: 0;
  background: var(--bg);
  scroll-behavior: smooth;
}

body {
  min-width: 0;
  margin: 0;
  color: var(--ink);
  background: var(--bg);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 15px;
  line-height: 1.5;
  letter-spacing: 0;
}

button,
select,
textarea,
input {
  color: inherit;
  font: inherit;
  letter-spacing: 0;
}

button,
.import-action {
  min-height: 38px;
  border: 1px solid #adb9b4;
  border-radius: 5px;
  background: var(--surface);
  cursor: pointer;
  padding: 7px 12px;
  font-weight: 650;
}

button:hover,
.import-action:hover {
  border-color: var(--accent);
  color: var(--accent);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

button.primary {
  border-color: var(--accent);
  color: #fff;
  background: var(--accent);
}

button.danger {
  border-color: #d2a89d;
  color: var(--warn);
}

a {
  color: inherit;
}

.app-header {
  position: sticky;
  z-index: 20;
  top: 0;
  display: grid;
  grid-template-columns: minmax(210px, 0.8fr) minmax(500px, 2fr) auto;
  gap: 18px;
  align-items: center;
  min-height: 68px;
  padding: 10px 24px;
  border-bottom: 1px solid var(--line);
  background: rgb(255 255 255 / 96%);
  backdrop-filter: blur(12px);
}

.brand-block {
  display: flex;
  min-width: 0;
  flex-direction: column;
}

.brand {
  overflow: hidden;
  color: var(--ink);
  font-size: 19px;
  font-weight: 800;
  text-decoration: none;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.demo-label {
  color: var(--gold);
  font-size: 11px;
  font-weight: 700;
}

.primary-nav {
  display: flex;
  min-width: 0;
  flex-wrap: wrap;
  gap: 2px;
}

.primary-nav a {
  border-radius: 4px;
  color: var(--muted);
  padding: 7px 9px;
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
}

.primary-nav a:hover,
.primary-nav a.is-active {
  color: var(--accent);
  background: var(--accent-soft);
}

.header-actions {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
}

.header-actions button,
.header-actions .import-action {
  min-height: 34px;
  padding: 5px 9px;
  font-size: 12px;
  white-space: nowrap;
}

.import-action input {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
}

.app-main {
  width: min(1500px, 100%);
  min-height: calc(100vh - 68px);
  margin: 0 auto;
  padding: 26px;
}

.page-heading {
  display: flex;
  gap: 20px;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 22px;
}

.page-heading h1 {
  margin: 0;
  font-size: 29px;
  line-height: 1.15;
}

.page-heading p {
  max-width: 760px;
  margin: 5px 0 0;
  color: var(--muted);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
}

.section-heading {
  display: flex;
  gap: 12px;
  align-items: center;
  justify-content: space-between;
  margin: 0 0 12px;
}

.section-heading h2,
.section-heading h3 {
  margin: 0;
  font-size: 18px;
}

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

.small {
  font-size: 12px;
}

.empty-state,
.loading-state {
  padding: 36px 0;
  color: var(--muted);
}

.metric-strip {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-block: 1px solid var(--line);
  background: var(--surface);
}

.metric {
  min-width: 0;
  padding: 18px;
  border-right: 1px solid var(--line);
}

.metric:last-child {
  border-right: 0;
}

.metric strong {
  display: block;
  font-size: 25px;
  line-height: 1.2;
}

.metric span {
  color: var(--muted);
  font-size: 12px;
}

.progress-track {
  height: 5px;
  margin-top: 10px;
  overflow: hidden;
  border-radius: 3px;
  background: #e6ebe8;
}

.progress-track span {
  display: block;
  height: 100%;
  background: var(--accent);
}

.dashboard-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(290px, 0.8fr);
  gap: 24px;
  margin-top: 24px;
}

.panel {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}

.panel + .panel {
  margin-top: 16px;
}

.list-reset {
  margin: 0;
  padding: 0;
  list-style: none;
}

.activity-list li,
.issue-list li,
.compact-list li {
  display: flex;
  min-width: 0;
  gap: 10px;
  align-items: flex-start;
  justify-content: space-between;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.activity-list li:last-child,
.issue-list li:last-child,
.compact-list li:last-child {
  border-bottom: 0;
}

.activity-list button,
.node-link {
  min-height: 0;
  border: 0;
  color: var(--accent);
  background: transparent;
  padding: 0;
  text-align: left;
}

.badge,
.status-pill,
.source-tag {
  display: inline-flex;
  max-width: 100%;
  align-items: center;
  border-radius: 999px;
  padding: 3px 8px;
  font-size: 11px;
  font-weight: 750;
  line-height: 1.3;
}

.badge {
  color: var(--muted);
  background: var(--surface-soft);
}

.badge.warning,
.status-pill.unresolved {
  color: var(--warn);
  background: var(--warn-soft);
}

.status-pill.resolved,
.status-pill.mastered {
  color: var(--accent);
  background: var(--accent-soft);
}

.status-pill.learning,
.status-pill.comfortable {
  color: var(--blue);
  background: var(--blue-soft);
}

.status-pill.unstable {
  color: var(--gold);
  background: var(--gold-soft);
}

.status-pill.not-studied {
  color: var(--muted);
  background: var(--surface-soft);
}

.source-tag.repertoire {
  color: var(--accent);
  background: var(--accent-soft);
}

.source-tag.alternative {
  color: var(--blue);
  background: var(--blue-soft);
}

.source-tag.historical {
  color: var(--gold);
  background: var(--gold-soft);
}

.source-tag.engine {
  color: #71428a;
  background: #efe4f4;
}

.source-tag.heuristic {
  color: var(--muted);
  background: var(--surface-soft);
}

.repertoire-layout,
.study-layout,
.trainer-layout,
.coverage-layout {
  display: grid;
  grid-template-columns: minmax(270px, 0.75fr) minmax(0, 1.75fr);
  gap: 22px;
  align-items: start;
}

.tree-group {
  margin-bottom: 18px;
}

.tree-group h2 {
  margin: 0 0 8px;
  font-size: 15px;
}

.tree-list,
.tree-list ul {
  margin: 0;
  padding-left: 17px;
  list-style: none;
}

.tree-list > li {
  padding-left: 0;
}

.tree-node {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 8px;
  align-items: center;
  padding: 7px 0;
}

.tree-node::before {
  position: absolute;
  left: -13px;
  color: #aab4b0;
  content: "└";
}

.tree-node button {
  min-height: 0;
  overflow: hidden;
  border: 0;
  background: transparent;
  padding: 0;
  text-align: left;
  text-overflow: ellipsis;
}

.tree-node-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  justify-content: flex-end;
}

.node-detail h2 {
  margin: 0;
  font-size: 22px;
}

.node-detail .line {
  margin: 6px 0 16px;
  color: var(--blue);
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
}

.detail-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 24px;
}

.detail-block {
  min-width: 0;
  padding: 13px 0;
  border-top: 1px solid var(--line);
}

.detail-block h3 {
  margin: 0 0 6px;
  color: var(--muted);
  font-size: 12px;
  text-transform: uppercase;
}

.detail-block p,
.detail-block ul {
  margin: 0;
}

.detail-block ul {
  padding-left: 18px;
}

.study-layout {
  grid-template-columns: minmax(300px, 640px) minmax(340px, 1fr);
}

.board-column {
  min-width: 0;
}

.board-shell {
  display: grid;
  width: min(100%, 640px);
  grid-template-columns: 20px minmax(0, 1fr);
  grid-template-rows: minmax(0, 1fr) 20px;
  gap: 4px;
}

.chess-board {
  display: grid;
  width: 100%;
  overflow: hidden;
  grid-column: 2;
  grid-row: 1;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  aspect-ratio: 1;
  border: 1px solid #64736d;
  box-shadow: var(--shadow);
}

.board-square {
  position: relative;
  display: grid;
  min-width: 0;
  border: 0;
  border-radius: 0;
  place-items: center;
  padding: 0;
  aspect-ratio: 1;
}

.board-square.light {
  background: var(--board-light);
}

.board-square.dark {
  background: var(--board-dark);
}

.board-square.is-last {
  box-shadow: inset 0 0 0 5px rgb(213 195 92 / 70%);
}

.board-square img {
  display: block;
  width: 86%;
  height: 86%;
  object-fit: contain;
  pointer-events: none;
}

.rank-labels,
.file-labels {
  display: grid;
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
}

.rank-labels {
  grid-column: 1;
  grid-row: 1;
  grid-template-rows: repeat(8, 1fr);
}

.rank-labels span {
  display: grid;
  place-items: center;
}

.file-labels {
  grid-column: 2;
  grid-row: 2;
  grid-template-columns: repeat(8, 1fr);
}

.file-labels span {
  text-align: center;
}

.board-toolbar,
.study-selectors,
.trainer-actions,
.filter-row,
.engine-actions {
  display: flex;
  min-width: 0;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-bottom: 12px;
}

.board-toolbar button {
  width: 40px;
  min-height: 38px;
  padding: 0;
  font-size: 20px;
}

.study-selectors select,
.filter-row select,
.filter-row input {
  min-height: 38px;
  max-width: 100%;
  border: 1px solid #adb9b4;
  border-radius: 5px;
  background: var(--surface);
  padding: 6px 9px;
}

.position-code {
  overflow-wrap: anywhere;
  color: #41524b;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
}

.move-context {
  display: flex;
  min-height: 44px;
  flex-wrap: wrap;
  gap: 5px;
  align-items: center;
  margin: 12px 0;
}

.move-context button {
  min-height: 30px;
  padding: 4px 7px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
}

.move-context button.is-current {
  border-color: var(--accent);
  color: #fff;
  background: var(--accent);
}

.study-content {
  min-width: 0;
}

.study-content .panel {
  margin-bottom: 14px;
}

.choice-row {
  display: flex;
  gap: 10px;
  align-items: baseline;
  padding: 8px 0;
  border-bottom: 1px solid var(--line);
}

.choice-row:last-child {
  border-bottom: 0;
}

.move-san {
  color: var(--accent);
  font-size: 20px;
  font-weight: 800;
}

.notes-field {
  width: 100%;
  min-height: 94px;
  resize: vertical;
  border: 1px solid var(--line);
  border-radius: 5px;
  padding: 9px;
}

.mastery-select {
  min-height: 36px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--surface);
  padding: 6px 8px;
}

.engine-output {
  margin: 10px 0 0;
  overflow-x: auto;
  border-left: 3px solid #71428a;
  background: #f7f3f9;
  padding: 10px 12px;
  color: #44324c;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
  white-space: pre-wrap;
}

.transposition-list,
.structure-grid,
.mistake-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.transposition-card,
.structure-card,
.mistake-card {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  padding: 16px;
}

.transposition-card h2,
.structure-card h2,
.mistake-card h2 {
  margin: 0 0 8px;
  font-size: 17px;
}

.path-line {
  margin: 8px 0;
  border-left: 3px solid var(--blue);
  padding-left: 10px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
}

.structure-card dl,
.mistake-card dl {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr);
  gap: 7px 12px;
  margin: 12px 0 0;
}

.structure-card dt,
.mistake-card dt {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.structure-card dd,
.mistake-card dd {
  min-width: 0;
  margin: 0;
}

.trainer-layout {
  grid-template-columns: minmax(280px, 0.7fr) minmax(0, 1.3fr);
}

.trainer-prompt {
  min-height: 260px;
}

.trainer-prompt h2 {
  margin: 10px 0;
  font-size: 24px;
}

.trainer-feedback {
  margin-top: 20px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.trainer-engine {
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.answer-options {
  display: grid;
  gap: 8px;
  margin: 16px 0;
}

.answer-options button {
  text-align: left;
}

.answer-options button.is-correct {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.answer-options button.is-wrong {
  border-color: var(--warn);
  color: var(--warn);
  background: var(--warn-soft);
}

.rating-actions button[data-rating="forgot"] {
  color: var(--warn);
}

.rating-actions button[data-rating="easy"] {
  color: var(--accent);
}

.mistake-controls {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 8px;
  margin-top: 12px;
}

.mistake-controls textarea {
  min-height: 70px;
  resize: vertical;
}

.coverage-layout {
  grid-template-columns: minmax(250px, 0.7fr) minmax(0, 1.3fr);
}

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

.check-summary strong {
  font-size: 26px;
}

.issue-row {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr) auto;
  gap: 10px;
  align-items: start;
  padding: 11px 0;
  border-bottom: 1px solid var(--line);
}

.issue-row:last-child {
  border-bottom: 0;
}

.issue-row code {
  overflow-wrap: anywhere;
}

.toast {
  position: fixed;
  z-index: 50;
  right: 20px;
  bottom: 20px;
  max-width: min(360px, calc(100vw - 40px));
  transform: translateY(14px);
  border-radius: 5px;
  color: #fff;
  background: #29332f;
  padding: 10px 14px;
  opacity: 0;
  pointer-events: none;
  transition: 160ms ease;
}

.toast.is-visible {
  transform: translateY(0);
  opacity: 1;
}

@media (max-width: 1120px) {
  .app-header {
    grid-template-columns: minmax(190px, 0.7fr) minmax(0, 2fr);
  }

  .header-actions {
    grid-column: 1 / -1;
    justify-content: flex-start;
  }

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

  .metric:nth-child(2) {
    border-right: 0;
  }

  .metric:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line);
  }
}

@media (max-width: 820px) {
  .app-header {
    position: static;
    display: block;
    padding: 12px 14px;
  }

  .brand-block {
    margin-bottom: 8px;
  }

  .header-actions {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    margin-top: 8px;
  }

  .header-actions button,
  .header-actions .import-action {
    display: grid;
    width: 100%;
    place-items: center;
  }

  .primary-nav {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .primary-nav a {
    overflow: hidden;
    padding-inline: 5px;
    text-align: center;
    text-overflow: ellipsis;
    white-space: nowrap;
  }

  .app-main {
    min-height: 0;
    padding: 18px 14px 32px;
  }

  .page-heading {
    display: block;
  }

  .dashboard-grid,
  .repertoire-layout,
  .study-layout,
  .trainer-layout,
  .coverage-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .board-shell {
    margin-inline: auto;
  }

  .transposition-list,
  .structure-grid,
  .mistake-grid {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (max-width: 480px) {
  body {
    font-size: 14px;
  }

  .brand {
    font-size: 18px;
  }

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

  .page-heading h1 {
    font-size: 25px;
  }

  .metric-strip {
    grid-template-columns: minmax(0, 1fr);
  }

  .metric,
  .metric:nth-child(2) {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .metric:last-child {
    border-bottom: 0;
  }

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

  .panel,
  .transposition-card,
  .structure-card,
  .mistake-card {
    padding: 14px;
  }

  .structure-card dl,
  .mistake-card dl {
    grid-template-columns: minmax(0, 1fr);
    gap: 2px;
  }

  .structure-card dd,
  .mistake-card dd {
    margin-bottom: 8px;
  }

  .issue-row {
    grid-template-columns: 72px minmax(0, 1fr);
  }

  .issue-row .node-link {
    grid-column: 2;
  }
}