:root {
  --ink: #17211c;
  --muted: #607068;
  --line: #c9d3ce;
  --line-dark: #8da099;
  --sheet-line: #d7dfdc;
  --paper: #f7f8f5;
  --panel: #ffffff;
  --excel: #107c41;
  --excel-dark: #0d5d35;
  --blue: #1f5f9c;
  --amber: #b7791f;
  --red: #b42318;
  --green-soft: #e7f4ec;
  --blue-soft: #e7f0fb;
  --amber-soft: #fbf0da;
  --red-soft: #fde8e5;
  --shadow: 0 24px 70px rgba(26, 38, 33, 0.14);
  --sans: "Space Grotesk", Arial, sans-serif;
  --serif: "Instrument Serif", Georgia, serif;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(23, 33, 28, 0.055) 1px, transparent 1px),
    linear-gradient(rgba(23, 33, 28, 0.04) 1px, transparent 1px),
    var(--paper);
  background-size: 32px 32px, 32px 32px, auto;
  font-family: var(--sans);
  letter-spacing: 0;
}

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

button {
  cursor: pointer;
}

a {
  color: inherit;
}

.overview-body {
  background:
    linear-gradient(90deg, rgba(23, 33, 28, 0.055) 1px, transparent 1px),
    linear-gradient(rgba(23, 33, 28, 0.04) 1px, transparent 1px),
    #f4f6f2;
  background-size: 32px 32px, 32px 32px, auto;
}

.overview-topbar,
.project-overview {
  width: min(1180px, calc(100% - 36px));
  margin: 0 auto;
}

.overview-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 0;
}

.overview-play-link,
.launch-button,
.secondary-link {
  text-decoration: none;
}

.overview-play-link,
.launch-button {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  font-weight: 900;
}

.overview-play-link {
  border: 1px solid var(--line);
  padding: 0 14px;
  background: #ffffff;
  color: var(--excel-dark);
}

.project-overview {
  display: grid;
  gap: 28px;
  padding: 18px 0 56px;
}

.overview-hero {
  display: grid;
  grid-template-columns: minmax(0, 0.82fr) minmax(420px, 1fr);
  gap: 24px;
  align-items: center;
  min-height: calc(100vh - 112px);
}

.overview-copy {
  display: grid;
  gap: 18px;
  align-content: center;
}

.overview-copy h1,
.overview-section h2,
.overview-section-heading h2,
.overview-cta h2 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 400;
  line-height: 0.94;
}

.overview-copy h1 {
  font-size: clamp(4.8rem, 12vw, 10rem);
}

.overview-copy p {
  max-width: 620px;
  margin: 0;
  color: var(--muted);
  font-size: 1.08rem;
  line-height: 1.65;
}

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

.launch-button {
  min-width: 158px;
  border: 1px solid var(--excel-dark);
  padding: 0 18px;
  background: var(--excel);
  color: #ffffff;
}

.secondary-link {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0 16px;
  background: #ffffff;
  color: var(--muted);
  font-weight: 900;
}

.overview-sheet {
  border: 1px solid var(--line-dark);
  border-radius: 8px;
  background: #ffffff;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.preview-ribbon {
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  min-height: 46px;
  border-bottom: 1px solid var(--line);
  background: #eef3f0;
}

.preview-ribbon span,
.preview-ribbon strong {
  display: grid;
  align-items: center;
}

.preview-ribbon span {
  place-items: center;
  border-right: 1px solid var(--line);
  color: var(--blue);
  font-family: var(--serif);
  font-size: 1.2rem;
  font-style: italic;
}

.preview-ribbon strong {
  padding: 0 12px;
  color: var(--ink);
  font-size: 0.95rem;
}

.preview-grid {
  display: grid;
  grid-template-columns: 44px repeat(4, minmax(0, 1fr));
  overflow: hidden;
}

.preview-grid > * {
  min-height: 46px;
  border-right: 1px solid var(--sheet-line);
  border-bottom: 1px solid var(--sheet-line);
  padding: 12px 10px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.preview-grid b {
  background: #e9efec;
  color: #4f5f58;
  font-size: 0.78rem;
  text-align: center;
}

.preview-grid strong {
  background: #ddeee5;
  color: var(--excel-dark);
}

.preview-grid em {
  background: var(--green-soft);
  color: var(--excel-dark);
  font-style: normal;
  font-weight: 900;
  box-shadow: inset 0 0 0 3px var(--excel);
}

.overview-section {
  display: grid;
  grid-template-columns: minmax(0, 0.75fr) minmax(320px, 0.85fr);
  gap: 24px;
  align-items: start;
  padding: 34px 0;
  border-top: 1px solid var(--line);
}

.overview-section h2,
.overview-section-heading h2,
.overview-cta h2 {
  font-size: clamp(2.4rem, 5vw, 4.8rem);
}

.overview-section > p,
.overview-steps {
  margin: 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.7;
}

.overview-band {
  display: grid;
  gap: 20px;
  padding: 34px 0;
  border-top: 1px solid var(--line);
}

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

.overview-grid article {
  display: grid;
  gap: 10px;
  align-content: start;
  border: 1px solid var(--line-dark);
  border-radius: 8px;
  padding: 16px;
  background: rgba(255, 255, 255, 0.88);
}

.overview-grid span {
  display: inline-grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--excel-dark);
  font-size: 0.8rem;
  font-weight: 900;
}

.overview-grid h3 {
  margin: 0;
  font-size: 1.08rem;
}

.overview-grid p {
  margin: 0;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.5;
}

.overview-steps {
  display: grid;
  gap: 8px;
  padding-left: 22px;
}

.overview-cta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 28px 0 0;
  border-top: 1px solid var(--line);
}

.workbook-app {
  display: grid;
  min-height: 100vh;
  grid-template-rows: auto auto minmax(0, 1fr);
}

.topbar {
  display: grid;
  grid-template-columns: minmax(130px, 0.3fr) minmax(240px, 1fr) auto;
  gap: 16px;
  align-items: center;
  padding: 14px 18px;
  border-bottom: 1px solid var(--line);
  background: #f0f4f1;
}

.site-link {
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 700;
  text-decoration: none;
}

.site-link:hover {
  color: var(--excel-dark);
}

.workbook-title {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.workbook-mark {
  display: inline-grid;
  width: 34px;
  height: 34px;
  flex: 0 0 auto;
  place-items: center;
  border-radius: 8px;
  background: var(--excel);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.22);
}

.workbook-mark::before {
  color: #ffffff;
  font-size: 1rem;
  font-weight: 800;
  content: "X";
}

.workbook-title strong,
.workbook-title span {
  display: block;
}

.workbook-title strong {
  font-size: 1.1rem;
}

.workbook-title span {
  color: var(--muted);
  font-size: 0.88rem;
}

.scoreboard {
  display: grid;
  grid-template-columns: repeat(4, minmax(76px, 1fr));
  gap: 8px;
  margin: 0;
}

.scoreboard div {
  min-height: 48px;
  padding: 7px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
}

.scoreboard dt {
  margin: 0;
  color: var(--muted);
  font-size: 0.73rem;
  font-weight: 700;
}

.scoreboard dd {
  margin: 1px 0 0;
  font-size: 1.1rem;
  font-weight: 800;
}

.ribbon {
  display: grid;
  grid-template-columns: auto minmax(360px, 1fr) minmax(220px, 0.55fr);
  gap: 14px;
  align-items: center;
  min-height: 76px;
  padding: 10px 18px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
  box-shadow: 0 8px 28px rgba(26, 38, 33, 0.08);
  z-index: 2;
}

.ribbon-tabs,
.ribbon-tools {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
}

.ribbon-tab,
.tool-button,
.next-button {
  min-height: 40px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  color: var(--ink);
  font-weight: 800;
}

.ribbon-tab {
  width: 86px;
}

.ribbon-tab.active {
  border-color: var(--excel);
  background: var(--green-soft);
  color: var(--excel-dark);
}

.tool-button {
  min-width: 96px;
  padding: 0 14px;
}

.tool-button.primary,
.next-button {
  border-color: var(--excel-dark);
  background: var(--excel);
  color: #ffffff;
}

.tool-button:hover,
.next-button:hover {
  border-color: var(--excel-dark);
}

.shortcut-chip {
  min-height: 42px;
  margin: 0;
  padding: 9px 12px;
  border: 1px solid #d7c399;
  border-radius: 8px;
  background: var(--amber-soft);
  color: #5f4211;
  font-size: 0.86rem;
  line-height: 1.35;
}

.game-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 360px);
  gap: 18px;
  min-height: 0;
  padding: 18px;
}

.sheet-area {
  display: grid;
  grid-template-rows: auto auto minmax(0, 1fr) auto;
  min-width: 0;
  min-height: 0;
  border: 1px solid var(--line-dark);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
  contain: layout paint;
  overflow: hidden;
}

.formula-strip {
  display: grid;
  grid-template-columns: 120px minmax(0, 1fr);
  gap: 8px;
  align-items: center;
  padding: 10px;
  border-bottom: 1px solid var(--line);
  background: #eef3f0;
}

.name-box,
.formula-box {
  display: grid;
  align-items: center;
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #ffffff;
}

.name-box {
  grid-template-columns: 38px minmax(0, 1fr);
}

.formula-box {
  grid-template-columns: 42px minmax(0, 1fr);
}

.name-box span,
.formula-box span {
  display: grid;
  min-height: 38px;
  place-items: center;
  border-right: 1px solid var(--line);
  color: var(--muted);
  font-weight: 800;
}

.formula-box span {
  color: var(--blue);
  font-family: var(--serif);
  font-size: 1.28rem;
  font-style: italic;
}

.name-box input,
.formula-box input {
  width: 100%;
  min-height: 38px;
  border: 0;
  border-radius: 6px;
  padding: 0 10px;
  outline: none;
  background: transparent;
}

.formula-box input:focus {
  box-shadow: inset 0 0 0 2px var(--excel);
}

.formula-help {
  min-height: 34px;
  margin: 0;
  padding: 8px 12px;
  border-bottom: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.88rem;
}

.sheet-scroll {
  min-height: 420px;
  contain: content;
  overflow: auto;
  outline: none;
  background: #ffffff;
}

.sheet-scroll:focus {
  box-shadow: inset 0 0 0 2px rgba(16, 124, 65, 0.28);
}

.sheet-grid {
  width: 100%;
  min-width: 1040px;
  border-collapse: separate;
  border-spacing: 0;
  table-layout: fixed;
}

.sheet-grid th,
.sheet-grid td {
  height: 38px;
  border-right: 1px solid var(--sheet-line);
  border-bottom: 1px solid var(--sheet-line);
  padding: 0;
  vertical-align: middle;
}

.sheet-grid thead th {
  position: sticky;
  top: 0;
  z-index: 1;
  height: 34px;
  background: #e9efec;
  color: #4f5f58;
  font-size: 0.78rem;
  font-weight: 800;
  text-align: center;
}

.corner-cell,
.row-heading {
  width: 48px;
  background: #e9efec;
  color: #4f5f58;
  font-size: 0.78rem;
  font-weight: 800;
  text-align: center;
}

.row-heading {
  position: sticky;
  left: 0;
  z-index: 1;
}

.corner-cell {
  position: sticky;
  left: 0;
  z-index: 2;
}

.cell-button {
  display: block;
  width: 100%;
  height: 38px;
  border: 0;
  border-radius: 0;
  padding: 0 9px;
  overflow: hidden;
  background: #ffffff;
  color: var(--ink);
  font-size: 0.86rem;
  line-height: 38px;
  text-align: left;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.cell-button:hover {
  background: #f4f8f6;
}

.cell-button.title {
  background: #ddeee5;
  color: var(--excel-dark);
  font-size: 0.78rem;
  font-weight: 900;
}

.cell-button.header {
  background: #f0f4f1;
  color: #33423b;
  font-weight: 900;
}

.cell-button.label {
  color: var(--muted);
  font-weight: 800;
}

.cell-button.number,
.cell-button.currency {
  text-align: right;
}

.cell-button.note {
  background: var(--blue-soft);
  color: #164a7d;
  font-size: 0.74rem;
}

.cell-button.target {
  background: #ecf8f1;
  box-shadow: inset 0 0 0 2px rgba(16, 124, 65, 0.28);
}

.cell-button.active {
  background: #ffffff;
  box-shadow: inset 0 0 0 3px var(--excel);
}

.cell-button.correct {
  background: var(--green-soft);
  color: var(--excel-dark);
  font-weight: 900;
}

.cell-button.wrong {
  background: var(--red-soft);
  color: var(--red);
  font-weight: 900;
}

.cell-button.empty-target {
  color: rgba(16, 124, 65, 0.52);
  font-style: italic;
}

.sheet-tabs {
  display: flex;
  gap: 6px;
  min-height: 48px;
  align-items: center;
  padding: 8px 10px;
  border-top: 1px solid var(--line);
  background: #eef3f0;
  overflow-x: auto;
}

.sheet-tab {
  min-width: 112px;
  min-height: 32px;
  border: 1px solid var(--line);
  border-radius: 7px 7px 0 0;
  background: #ffffff;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 800;
}

.sheet-tab.active {
  border-color: var(--excel);
  background: var(--green-soft);
  color: var(--excel-dark);
}

.sheet-tab.complete {
  border-color: #9ec2ad;
  color: var(--excel-dark);
}

.task-pane {
  display: grid;
  grid-template-rows: auto auto 1fr;
  gap: 12px;
  min-width: 0;
  contain: layout;
}

.mission-panel,
.feedback-panel,
.guide-panel,
.coach-panel,
.dialog-card {
  border: 1px solid var(--line-dark);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.94);
  box-shadow: 0 14px 42px rgba(26, 38, 33, 0.1);
}

.mission-panel,
.feedback-panel,
.guide-panel,
.coach-panel {
  padding: 16px;
}

.pane-label {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 900;
  text-transform: uppercase;
}

.mission-panel h1,
.coach-panel h2,
.dialog-card h2 {
  margin: 0 0 10px;
  font-family: var(--serif);
  font-weight: 400;
  line-height: 1;
}

.mission-panel h1 {
  font-size: 2.2rem;
}

.coach-panel h2,
.dialog-card h2 {
  font-size: 1.8rem;
}

.mission-panel p,
.feedback-panel p,
.coach-panel p,
.dialog-card p {
  margin-top: 0;
  color: var(--muted);
  line-height: 1.55;
}

.progress-track {
  height: 10px;
  margin: 14px 0;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #eef3f0;
  overflow: hidden;
}

.progress-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--excel), var(--blue));
  transition: width 220ms ease;
}

.objectives {
  display: grid;
  gap: 8px;
  margin: 0;
  padding-left: 22px;
  color: var(--ink);
}

.objectives li {
  line-height: 1.45;
}

.feedback-panel {
  border-color: #d7c399;
  background: #fffaf0;
}

.feedback-panel.success {
  border-color: #9ec2ad;
  background: #f1fbf4;
}

.feedback-panel.error {
  border-color: #e2aaa4;
  background: #fff4f2;
}

.next-button {
  width: 100%;
  margin-top: 10px;
}

.guide-panel {
  display: grid;
  gap: 12px;
}

.guide-panel[hidden] {
  display: none;
}

.guide-header {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
}

.guide-header h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.8rem;
  font-weight: 400;
  line-height: 1;
}

.guide-header span {
  min-width: 54px;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 5px 8px;
  background: #ffffff;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 900;
  text-align: center;
}

.guide-steps {
  display: grid;
  gap: 10px;
}

.guide-step {
  display: none;
  gap: 9px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fbfdfb;
  contain: content;
}

.guide-step.active {
  display: grid;
}

.guide-step h3 {
  margin: 0;
  font-size: 1rem;
  line-height: 1.18;
}

.guide-step p {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.45;
}

.guide-step p strong {
  color: var(--ink);
}

.guide-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.formula-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.system-drill {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

.system-drill ol {
  display: grid;
  gap: 7px;
  margin: 0;
  padding-left: 20px;
}

.system-drill li {
  color: var(--ink);
  font-size: 0.9rem;
  line-height: 1.42;
}

.shortcut-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-top: 14px;
}

.shortcut-grid span {
  display: grid;
  min-height: 38px;
  align-content: center;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 8px;
  background: #f8faf8;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
  line-height: 1.24;
}

.shortcut-grid kbd {
  display: inline-block;
  margin-bottom: 2px;
  color: var(--excel-dark);
  font-family: var(--sans);
  font-size: 0.76rem;
  font-weight: 900;
}

.formula-tags span {
  min-height: 30px;
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: #ffffff;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 800;
}

.completion-dialog {
  width: min(480px, calc(100% - 32px));
  border: 0;
  padding: 0;
  border-radius: 10px;
  background: transparent;
}

.completion-dialog::backdrop {
  background: rgba(11, 22, 17, 0.42);
}

.dialog-card {
  padding: 22px;
}

.dialog-card .tool-button {
  width: 100%;
}

@media (max-width: 1060px) {
  .overview-hero,
  .overview-section {
    grid-template-columns: 1fr;
  }

  .overview-hero {
    min-height: auto;
    padding-top: 28px;
  }

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

  .topbar,
  .ribbon,
  .game-layout {
    grid-template-columns: 1fr;
  }

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

  .ribbon-tools {
    flex-wrap: wrap;
  }

  .shortcut-chip {
    width: 100%;
  }

  .game-layout {
    min-height: auto;
  }

  .task-pane {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .overview-topbar,
  .project-overview {
    width: min(100% - 20px, 1180px);
  }

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

  .overview-play-link,
  .launch-button,
  .secondary-link {
    width: 100%;
  }

  .overview-copy h1 {
    font-size: clamp(4.2rem, 22vw, 5.8rem);
  }

  .overview-sheet {
    overflow-x: auto;
  }

  .preview-grid {
    min-width: 620px;
  }

  .overview-grid,
  .overview-cta {
    grid-template-columns: 1fr;
  }

  .overview-grid {
    display: grid;
  }

  .overview-cta {
    display: grid;
  }

  .topbar,
  .ribbon,
  .game-layout {
    padding: 10px;
  }

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

  .ribbon-tabs,
  .ribbon-tools {
    width: 100%;
    overflow-x: auto;
  }

  .formula-strip {
    grid-template-columns: 1fr;
  }

  .sheet-grid {
    min-width: 920px;
  }

  .mission-panel h1 {
    font-size: 1.9rem;
  }

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