:root {
  color-scheme: light;
  --bg: #f3f4f6;
  --panel: #ffffff;
  --text: #111827;
  --muted: #6b7280;
  --border: #d1d5db;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --danger: #dc2626;
  --shadow: 0 20px 45px rgba(15, 23, 42, 0.12);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
}

button,
input,
select {
  font: inherit;
}

button,
.back-link {
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
  padding: 8px 12px;
  cursor: pointer;
  text-decoration: none;
  white-space: nowrap;
}

button:hover,
.back-link:hover {
  border-color: var(--primary);
}

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

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

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

.home-page {
  display: grid;
  place-items: center;
  padding: 32px;
  background: linear-gradient(135deg, #dbeafe, #f8fafc 50%, #dcfce7);
}

.home-shell {
  width: min(980px, 100%);
}

.hero {
  margin-bottom: 28px;
  text-align: center;
}

.eyebrow {
  color: var(--primary);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 8px 0 12px;
  font-size: clamp(32px, 6vw, 60px);
}

.hero p {
  color: var(--muted);
  font-size: 18px;
}

.app-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}

.app-card {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 28px;
  border: 1px solid rgba(255, 255, 255, 0.7);
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.82);
  box-shadow: var(--shadow);
  color: var(--text);
  text-decoration: none;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.app-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 25px 55px rgba(15, 23, 42, 0.18);
}

.card-icon {
  display: grid;
  place-items: center;
  flex: 0 0 64px;
  width: 64px;
  height: 64px;
  border-radius: 18px;
  color: #fff;
  font-size: 34px;
  font-weight: 800;
}

.word-card .card-icon {
  background: #2563eb;
}

.excel-card .card-icon {
  background: #16a34a;
}

.app-card strong,
.app-card small {
  display: block;
}

.app-card strong {
  margin-bottom: 6px;
  font-size: 24px;
}

.app-card small {
  color: var(--muted);
  line-height: 1.5;
}

.topbar,
.toolbar,
.formula-bar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  overflow-x: auto;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
}

.title-input,
.formula-bar input,
select {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 10px;
  background: #fff;
}

.title-input {
  min-width: 240px;
  font-weight: 700;
}

.status {
  min-width: 80px;
  color: #15803d;
  font-size: 14px;
}

.status.error {
  color: var(--danger);
}

.word-workspace {
  padding: 32px 16px;
}

.word-page {
  width: min(900px, 100%);
  min-height: 72vh;
  margin: 0 auto;
  padding: 56px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 4px;
  box-shadow: var(--shadow);
  line-height: 1.7;
  outline: none;
}

.word-page:focus {
  border-color: var(--primary);
}

.formula-bar {
  position: sticky;
  top: 57px;
  z-index: 15;
}

#activeCellLabel {
  min-width: 56px;
  padding: 8px 10px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: #f9fafb;
  font-weight: 700;
  text-align: center;
}

.formula-bar input {
  min-width: 420px;
  flex: 1;
}

.sheet-shell {
  height: calc(100vh - 162px);
  overflow: auto;
  background: #fff;
}

.sheet {
  display: grid;
  width: max-content;
  border-top: 1px solid var(--border);
  border-left: 1px solid var(--border);
}

.cell,
.header-cell,
.corner-cell {
  min-width: 96px;
  height: 30px;
  border-right: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 4px 6px;
  overflow: hidden;
  white-space: nowrap;
}

.corner-cell,
.header-cell {
  position: sticky;
  z-index: 4;
  background: #f3f4f6;
  color: var(--muted);
  font-weight: 700;
  text-align: center;
  user-select: none;
}

.corner-cell {
  left: 0;
  top: 0;
  z-index: 8;
  min-width: 54px;
}

.column-header {
  top: 0;
}

.row-header {
  left: 0;
  min-width: 54px;
}

.cell {
  background: #fff;
  outline: none;
}

.cell.active {
  box-shadow: inset 0 0 0 2px var(--primary);
  z-index: 3;
}

.toolbar label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
}

@media (max-width: 720px) {
  .word-page {
    padding: 24px;
  }

  .title-input,
  .formula-bar input {
    min-width: 220px;
  }
}